rexford

The following site has an interesting, although unreferenced, discussion of improvised cannister for 6 pdr guns in Africa. http://www.miniatures.de/html/int/shellsB.html Go down to the 6 pdr (57mm) info.

The following site has an interesting, although unreferenced, discussion of improvised cannister for 6 pdr guns in Africa. http://www.miniatures.de/html/int/shellsB.html Go down to the 6 pdr (57mm) info.

Once a Firefly fired, any questions regarding the type of Sherman were immediately answered. The noise and blast and flash were probably never confused with 75mm armed Shermans.

Using Tigers in France helped spread the Tigerphobia that could gain psychological benefits in terms of indecision and anxiety whenever a German tank was spotted or suspected. Tigers were also excellent killing machines, as Wittmann showed. Regarding Fireflies, they produced a terrific blast which gave away their position right away, and I read where their gunsights needed adjustment on a daily basis or errors could creep in. In the same vein, using APDS messed up the accuracy of follow-up APCBC shots. Tiger ammo, until late in the war, gave off relatively little smoke or flash (I forget which). There are reports where Tigers and Panthers hidden in a woods with camouflage could not be detected by British tank forces unless the camouflage was knocked away by the gun blast. Tiger sights, gun and ammunition produced one of the most accurate weapons of WW II, with very little shot to shot scatter. The Russians report 1000m to 1500m knockouts of 76.2mm field guns in prepared positions on the first shots by Tiger.

Has anyone come across after action reports, discussions or statements regarding the combat use of 17 pdr APDS against the Panther, where glacis penetrations were obtained. I've found reports where 17 pdr penetrated the Panther glacis during combat, but they don't say if it was APCBC or APDS. Thanks.

HE shells are used for two things, one is placing rounds close to an enemy on the ground with accuracy and a large blast area, the other is hitting things on the fly with accuracy and the blast isn't as important. Sherman 75mm HE would be great against ground targets where a slow velocity and large HE burst are desirable. Or you are trying to hit an 88mm Flak 36 on the fly and the gun is in the open (but if the range is too high a higher velocity would be better). To put HE directly on a target on the fly, such as an ATG shield, or through the slit on a bunker, or any number of other uses, high velocity and small HE do fine. Panther fired HE at 750 m/s, Tiger II at 700 m/s, 75L48 at 550 m/s, which is quite a bit below the muzzle velocity for their APCBC.

If a slope effect is applied to the 37mm L45 APCR penetration data at 30 degrees from vertical presented in Jentz, Encycl. of German Tanks of WW II and other publications, one obtains: 100m, 90mm vertical 500m, 48mm vertical The driver plate (75mm at 30 degrees from vertical) on KV-I would present about 105mm vertical resistance to 37mm APCR, although the tanks' nose and mantlet armor would be vulnerable at close range. If the 37mm APCR was used at about 10m it could probably defeat 75mm at 30 degrees. The turret side on KV-1, 75mm at about 15 degrees, could be wasted at about 200 meters when there was no side angle from firer to side armor facing..

British 2 pdr AP is a better panzer penetrator than 45mm gun up until early 1942 when 45mm guns get APCR. Penetration data follows: British 2 pdr AP vs Russian 45mm ammo. ====================================== British 2 pdr AP fired at 792 m/s Homogeneous armor 82mm at 100m, 63mm at 500m, 46mm at 1000m, 34mm at 1500m Face-hardened armor62mm at 100m, 50mm at 500m, 38mm at 1000m, 28mm at 1500m ======================================= Russian 45mm AP fired at 760 m/s Homogeneous armor 61mm at 100m, 46mm at 500m, 32mm at 1000m, 22mm at 1500m Face-hardened armor 53mm at 100m, 39mm at 500m, 27mm at 1000m, 19mm at 1500m ======================================== Russian 45mm APBC fired at 760 m/s (carries better with range due to aerodynamicallyt shaped ballistic cap windscreen) Homogeneous armor 62mm at 100m, 45mm at 500m, 35mm at 1000m, 29mm at 1500m Face-hardened armor 55mm at 100m, 46mm at 500m, 38mm at 1000m, 31mm at 1500m Russian 45mm ammo was softer than British 2 pdr AP and often contained an HE burster, so it penetrated less. Several sources indicate that 45mm ammo was badly manufactured/heat treated and suffered from brittle nose material, which decreased the above penetration estimates by -29% to -50%. The 45mm ammo penetration problems due to improper heat treatment were supposed to last throughout 1941, although several references say the problems lasted through 1943. See http://www.geocities.com/Pentagon/Base/1852/57mm.html#24 Some info suggests that 45mm ammo could not penetrate the 30mm armor on PzKpfw IIIG's beyond 500m during 1941 battles. However, 45mm guns fired cannister and had a very good HE round. 2 pdr fired neither in the desert through much of the campaign. One disadvantage of 2 pdr anti-tank guns is the shield armoring, where Germans used face-hardened shields which could bounce some bullets, while Brits did not face-harden gun shields based on the limited stuff I've read. If German tanks put an armor piercing round in their machine gun ammo 2 pdr ATG were in trouble. But even with AP bullets the shields might be too vulnerable. One other goodie. 2 pdr AP had a shatter gap problem against many panzers, where it would fail if it had too much penetration! This could result in a discontinuous penetration range, the gun would penetrate to 400m, then fail to 800m, then penetrate again for a further distance. Or the gun would fail from point blank to some close range, and then start penetrating. In a test against the Tiger homogeneous side armor at 100 yards, 2 pdr AP with 82mm penetration stuck in the side of the Tiger 62mm lower hull side and failed to completely penetrate. 2 pdr AP had many problems that don't show up in the data. However, I read an account of an Australian unit in the desert where a German armored car was driving away from the Aussies and was beyond the range markings for the 2 pdr ATG (beyond 2000 yards). An Australian soldier aimed the gun using an eyeball estimate for elevation and hit the armored car on the first shot, stopping the vehicle with a penetration of the rear armor. [ May 09, 2003, 08:38 PM: Message edited by: rexford ]

Another point is the Tiger turret side and turret rear is rounded and most hits won't strike flat on. The way I understand it, Tiger and Panther turret traverse was similar in many respects, we use 9 degrees per second for both tanks in our micro scale wargames. Sherman turret whizzed around at 24 degrees per second. On level ground, if a Sherman suddenly appears out of the blue facing the Tiger side armor, and the Tiger turret is pointed straight ahead, it will take the Tiger turret 10 seconds to rotate onto the Sherman once the Tiger crews knows where the threat is, the commander gives the order to traverse to the flank and the turret can actually be put into motion. If the Tiger is buttoned up by machine gun, HE or artillery fire the ability to see flank threats is greatly decreased. So a Sherman on the Tiger side may have 20 to 30 seconds to fire before the Tiger can move the gun onto the target. That's quite a few shots before the Tiger reacts and fires back, and even with low probability successes one might eventually get through (especially if several hits land close together and crack the armor or hit in the same groove, which would be a "weak spot" hit). That's if it's not possible to rotate the Tiger in place, but that takes time. The Biggest problem is seeing or becoming aware of a flank threat, making a decision to traverse the turret or rotate the Tiger, and having the order implemented. When Wittmann's Tiger was knocked out, the turret on his tank was rotated in the wrong direction, away from the threat. Some of the German commentators on Wittmann's demise were surprised that he was surprised, since they said that Wittmann had this sixth sense for smelling ambushes and enemy units. So rotating the gun away from the Firefly position was not expected. I don't know about you folks, but isn't it amazing that Wittmann's Tiger was 007, the same number immortalized by James Bond. Mickey Mantle, the greatest centerfielder ever, was also number 7, that no zero's in front. Anyway, Many folks think that tanks may react too fast in wargames as a general rule. The penetration data in CMBO is halfway correct by using a single figure for all target armor types (face-hardened and homogeneous): should be 81mm homogeneous at 500m and is 89mm, should be 95mm face-hardened and is 89mm. So Shermans are too effective against Tiger and Tiger II and less effective against PzKpfw IVH and StuG IIIG. But getting back to the turret traverse business, info posted on various web sites indicates that Tiger and Panther turret traverse really slows down if the vehicle is on any type of slope. Tigers do much better in CMBB. One other unrelated point. The report to Eisenhower noted that Tiger and other German gun sights were much better at light gathering than American sights, and the U.S. tanks had trouble sighting during reduced light conditions (overcast). There is an Eastern Front story where a Tiger was able to see, aim at, hit and knock out a large number of T34 that were forming up in a fog, and the Russian forces could not identify where the fire from coming from. Superior light gathering optics.

Italian armor on the M13/40 was very brittle, and penetrations by small rounds usually wiped out the entire crew due to flying fragments of armor on the inside of the tank. Those sand bags were piled on for a reason. Italian armor was short on alloys. During the research for our book we were furnished with a report by an Italian tanker who fought the Germans in Rome during September 1943, where he attempted to use the front of an M13/40 for an anvil to straighten a large nail and the nail left a scar in the armor. After 1941, Italian armor improved and penetration photo's do show clean holes instead of ragged ones although the resistance to penetration appears to have suffered even after the improvements. I read a small book by a unit using the 2 pdr Portee, where the gun was mounted on the back of trucks, barrel pointing towards the truck rear. GUNS AGAINST TANKS was the title, and I found it at the New York State Library. The gun crews found that one 2 pdr AP hit on a PzKpfw II or M13/40 was enough to stop the tank, but 2 to 3 were needed with PzKpfw IIIG (30mm frontal armor). 2 pdr penetrations were with 40mm solid shot that could fracture against face-hardened armor. With regard to small round damage, there is a picture of a Valentine tank that was penetrated about 25 or so times by 50mm AP and the crew had continued to fight on for some time.

I took a closer look at the data for slope effect and 75mm APCBC penetration, and the Tiger does even better than the estimates presented this morning. Sherman 75mm APCBC vs Tiger 82mm Side Armor Range Where 50% of Hits Completely Penetrate Impact angle.....Range for 82mm Penetration ..0 degrees.................440m ..5.........................375m .10.........................310m .15.........................150m .20...........................0m .25...........................no range .30...........................no range ============================================ Range Where 20% of Hits Completely Penetrate Impact angle.....Range for 82mm Penetration ..0 degrees.................750m ..5.........................625m .10.........................560m .15.........................440m .20.........................200m .25...........................0m .30...........................no range =========================================== By way of contrast, if the Panther A side hull (40mm at 40 degrees from vertical) is hit by Sherman 75mm with a 30 degree side angle, the resulting armor resistance is 72mm vertical. Sherman 75mm APCBC can defeat Panther A side hull on 50% of the hits at 1060m with a 30 side angle from firer to hull side! Same angle hit on Tiger side bounces off harmlessly every time at 250m range. Tiger side armor may not have a slope but it has the thickness. =========================================== We recently analyzed U.S. APCBC against face-hardened armor and it appears that 75mm and 76mm APCBC had extra effectiveness against face-hardened armor, which may have cost some homogeneous armor effectiveness. 75mm APCBC penetrates 95mm of face-hardened armor at 500m, but only 81mm homogeneous (Tiger armor type). The earlier 75mm M72 solid shot AP used by Shermans had penetration at 500m was 92mm homogeneous and 75mm face-hardened. What this means is Sherman 75mm APCBC stinks against tanks with thick homogeneous armor (Tiger and Tiger II) unless it lines up close to the armor facing, and eats up tanks with face-hardened frontal armor of 80mm or so thickness and little slope (PzKpfw IVH, StuG III and IV). If I wanted a German tank to fight the Allies in close country in France, and speed wasn't a big concern, Tiger would be my choice. [ May 09, 2003, 06:04 PM: Message edited by: rexford ]

If one compares the penetration data for Sherman 75mm APCBC in CMBO and CMBB they will see a decrease in the latest game. U.S. 75mm APCBC was softer than German 75mm APCBC and had a larger HE burster, which accounts for the decrease from one game to another. The CMBO is not as hair-splitting as CMBB. U.S. 75mm APCBC fired by the Sherman penetrated 81mm vertical armor at 500m. And about 86mm vertical at 250m. I think CMBO gives Sherman 75mm APCBC 89mm penetration at 500m and 0 degrees. With 82mm side armor, a Tiger could withstand Sherman 75mm APCBC hits at 250m and 20 degrees side angle and survive most of the time (82mm at 20 degrees is about 91mm vertical resistance, penetration is about 86mm). CMBO boosts the Sherman 75mm penetration by about 10% over U.S. firing trial data, and when is talking about close range hits with side angles that 10% addition makes the Tiger somewhat more vulnerable than it probably should be. The advantage of Tiger over Panther in close terrain is that Tiger armor presents a thicker hide against the Sherman, and Tiger often has the few more mm after a small angle is cranked in that mean the difference between life and death. When Wittmann's Tiger was knocked out, Tiger side armor defeated the 75mm hits at about 800 yards, a situation where Panther would have been a dead duck. If CMBO was going to be revised once more, this is what I would suggest: 1. half the 17 pdr and 6 pdr APDS shots go wild and won't penetrate anything if they hit 2. Sherman 75mm APCBC penetration decreased to agree with U.S. TM9-1907 3. Panther glacis penalty for flaws applied to a given percentage of tanks, not all 4. Panther glacis penalty would be a function of incoming round diameter, the penalty multiplier should be 0.95 against 75mm and 76mm (17 pdr, too) hits, and 0.90 against 90mm hits. 0.85 applies to 122mm hits based on our math. 5. Tiger side armor increased to 82mm, which is the historical average, and those additional 2mm really are important when it comes to the hair-splitting analysis of penetration vs armor resistance.

A U.S. firing test report was presented in our book where 90mm HVAP was fired against 8" armor at Brinell Hardnesses from 223 (somewhat soft for armor) to 390 (somewhat hard). The firing test results suggest that early Tiger 82mm and 62mm side plates, and maybe the 102mm front hull, would gain in resistance against tungsten core ammo. Firing 90mm HVAP against vertical plate, the U.S. limit velocities were: 2530 feet per second for 223 Brinell 2640 feet per second for 260 Brinell 2660 feet per second for 390 Brinell 2800 feet per second for 339 Brinell The 339 Brinell armor would be about +9.4% more effective than 260 Brinell in terms of vertical equivalence against 90mm HVAP. 8" armor against 90mm HVAP has about the same ratio of armor thickness/core width as 82mm versus 45mm APCR. While one firing trial does not a universe make, and random variations in projectile performance could account for the differences, the results do suggest that early Tiger armor might possibly obtain a small boost against Russian APCR hits due to the unusual hardness (315 to 360 Brinell).

Jason C stated: "The continual assumption that any Russian penetration report or data that indicates possible success against any sort of 80mm plate at any range must reflect "magic bullet" ammo, above that normally available, is tendentious reasoning, for which there is -no- evidence. Specifically, it is pure gratituous speculation that rounds used in any of the "offending" reports were above the average. That above average rounds existed may be true, but there has been no indication they were involved in any cited case. " Horsefeathers. Miles Krogfus' article clearly states that some of the BR-350B APBC were routinely heat treated for better penetration. In addition, the tests against Tiger II were conducted against the turret side, hull side and hull rear, and the penetration ranges were all consistent with an added 10% penetration. Anyway, you're never going to admit that we are being fair about things and that everything can be explained in a reasonable manner. And even if way above average BR-350B defeated the Tiger II, it still points out that average BR-350B could fail against the Tiger side, as well as below average. Lorrin

Jason C said: "Meanwhile, Rexford quoted a source of his own that a Tiger II, sloped, was penetrated from the side by Russian 76mm at ~300m, but now wants to believe 80mm flat never was at 100m. Because of "great news" from the same report that said PAK 40s with German ammo couldn't kill them at 500m, flat." Come on Jason, you missed the point. And you got the details all wrong. Here is a brief summary. ) My past posts said that: 1. 76.2 APBC failed against the King Tiger side in one series of tests, but maybe the specially treated round with 10% more penetration could explain a reported success in another test effort. 2. firing tests against 82mm side plates on early Tigers could have resulted in failed 76.2mm APBC hits because the unusually hard armor may have been a little bit more effective than the 82mm thickness 3. Some Tigers carried less effective plates on the side which the British termed "bad", probably easier to penetrate 4. At 100m against 82mm Tiger side armor, 76.2mm BR-350B has 81mm penetration and should succeed on about half the hits in the absence of a side angle. 5. With specially treated 76.2mm APBC (BR-350B), T34's and 76.2mm field guns should penetrate 82mm Tiger side plate on almost half the hits at 500m. 6. In two cases out of fourteen that we studied for early Tiger 82mm plate, the 82mm plates would resist like 77mm and 78mm, which standard 76.2mm APBC could penetrate at about 250m on a good percentage of hits. So, in conclusion, nothing I posted stated or even suggested that Russian 76.2mm APBC NEVER penetrated the Tiger 82mm side plates at 100m, or even 500m. And a 76.2mm APBC could penetrate the Tiger II's sloped side armor (80mm at 25 degrees) at 300m in one trial, and fail against 80mm vertical in another. It's a function of probability, different ammo characteristics and varying armor resistance. Lorrin

Originally posted by Kiff01: "Hello PzKpfw 1: Thanks for the clarification. I have read many of C.G. Erickson?s posts in the past. He seems rather blunt, but I have gotten the impression he works in and around tanks a great deal. Does he work at a museum, or is he some sort of tank mechanic?" Erickson welds some, and has posted pictures of himself changing the brakes on a Panther over the weekend. "Hello Lorrin: I?m not much on posting on forums, but in this case I am interested in the background of your manual Armor and Gunnery. Forgive me if I am breaching normal forum protocol. I think I might be able to manage opening a separate thread if my posts are distracting from the discussion on acronyms. ?Might? being the keyword. I am still trying to figure out the system here." The book combines the research efforts of Robert Livingston and myself, which goes back to the 1960's for each person. We got together in the early 1980's and had the same interests, plus we both wargamed and used the research to perfect a very detailed wargame. Miles Krogfus worked on the same issues and we got together through AFV News, we was a very effective getogether. We had ALOT of help from a series of folks who were mentioned in the front of the book, which includes Miles Krogfus (who has access to all sorts of German and Russian documents from WW II), John Waters and others. So it wasn't two grogs sitting in a den thinking up fancy theories in a vacuum. If you look at the book you'll see that we spend mucho time comparing our estimates against actual firing trials and combat reports. This isn't a selective "use the friendly stuff" kind of biased review, it includes everything we could find. In our gaming system, which is touched upon in the book, one uses the trajectory characteristics of projectiles, the random scatter pattern and statistical methods of modeling random range estimation errors to derive where the shot goes by the target relative to where it was aimed. If a Panther aims at the center of a Pershing profile at 1200m, our charts tell one which vertical and lateral shot scores to roll against. Which leads to a measurement as to where the round passed by the tank aim point (high or low, left or right). Our research lead me to spend untold hours at the State Museum where they had a LARGE collection of microfiche rolls of U.S. firing trials from WW II, and we bought alot of documents from NTIS. Look in the bibliography of our book and you'll see a small percentage of the actual documents we used. I do mathematical modeling for a living along with being a civil engineer, and we took the data and formed mathematical models. Math models for cast armor deficiency relative to rolled armor, high hardness armor relative to medium hardness, armor flaws, slope effect versus plate thickness/projectile diameter ratio, face-hardened penetration estimates, etc. "I purchased a copy of Armor & Gunnery about a month ago. It?s available from the Articles of War book site. I have been taken aback by some of the posts on AFV News. Has there been a great deal of errata put out for the manual? If so, is there somewhere a person can obtain all of the errata that has been put out for Armor & Gunnery?" If you bought the second edition it includes all of the errata prepared in the past. Do you want me to e-mail you the things I put together since Miles' article came out, which change some things a bit. Things are surfacing so fast nowadays that many books are outdated while they are at the printers. Miles Krogfus' discovery of the Russian ARTKOM equation and constants completely changes the view of the published Russian penetration figures. The discovery of the BIOS report that presents the German equation and constants for penetration at 30 degrees from normal will probably change the interpretation of the 30 degree penetration data in various books. But our vertical penetration figures for German ammo are still essentially the same as originally published. Some of the comments about my research and posts is good and made me look further into some issues, much of it is histrionics for whatever reason.

There are two firing trial results floating around the grog community, one where 76.2mm APBC is a total failure against Tiger II side armor and another where it succeeds at 300m. The results can be explained by examination of penetration estimates for typical and special heat treatment 76.2mm ammo. Working from the U.S. firing trials with 122mm APBC, 76.2mm APBC (BR-350B) would penetrate 76mm homogeneous armor on half the hits at 300m. Now that's a mouthful. The side armor on Tiger II would present 86mm resistance to 76.2mm APBC hits on turret side, and 89mm when rounds struck the hull superstructure side. 76mm penetration at 300m against 86mm and 89mm effective resistance will succeed on about 5% of the hits, at best. So firing tests with 76.2mm APBC would be expected to fail against the Tiger II side at 300m, as they did. Now, Miles Krogfus' article indicates that the Russians specially heat treated a small percentage of the 76.2mm APBC rounds, and the increased penetration would be about 10% (working from the constants in Miles Krogfus' article). So special 76.2mm APBC would penetrate 84mm at 300m, which is enough to defeat the 80mm at 20 degrees from vertical side plates on almost half the hits. Against 80mm at 25 degrees from vertical, 84mm penetration would succeed on 20% of the strikes, which is the Russian IP criteria (Initial Penetration). The inconsistencies in the firing test results against the side plates on Tiger II can be explained given assumptions that are consistent with information provided by Miles Krogfus in his article.

Miles Krogfus' article on the DeMarre Equation and ARTKOM provided some eye-opening insights into what the Russian penetration figures mean, namely that they are not pegged to medium hardness homogeneous armor plate. The article is not specific about the meaning of high hardness armor, and suggests, if one reads into the text, that high hardness is related to face-hardened armor. The Germans switching from high hardness to homogeneous armor is consistent with face-hardened to homogeneous armor, while high hardness homogeneous to medium hardness homogeneous would not. In reality, the appearance of Tiger tanks was a major transition from the face-hardened armor which had previously appeared on front of PzKpfw III and IV and StuG III, where all the plates on Tiger were homogeneous. While the initial Panther D and Panther A which the Russians fought appear to have carried face-hardened armor, information provided by Lawrence Sims some time ago indicated that Panther production went with all homogeneous armor types starting late 1943. A German Intelligence report on the SU 85 provides Russian penetration data for 85mm APBC (119mm at 100m, 111mm at 500m, 102mm at 1000m, etc.) with an explanation for the Russian data, which I translated to mean: "the penetration is calculated from the formula Jacob de Marre for a cemented armor plate using the coefficient K=2400." Plate is described as "eine zementier te panzerplatten". Converting the penetration figures to velocities using the ARTKOM equation and a constant of 2400 closely matches the assumed velocity-range profile for 85mm APBC. If the ARTKOM estimates are assumed to be against cemented or face-hardened it adds to the usefulness of Miles' article. The 76.2mm APBC BR-350B would penetrate 76mm face-hardened at 500m, 68mm at 1000m and 54mm at 2000m. The 50mm face-hardened armor on the front of PzKpfw III and IV, and StuG III, would be vulnerable at the 1500m range and beyond. But a PzKpfw IVH with 80mm frontal armor would be a hard nut to crack at 500m. The ARTKOM equation predicts 165mm penetration for 122mm AP (BR-471) at 0m, which is for 80% success. Converting to 50% success results in 175mm (1.06 multiplier). By way of comparison with Allied AP rounds and their ratio's of face-hardened to medium hardness homogeneous armor penetration, 122mm AP might penetrate about 201mm of vertical homogeneous armor at 0m. And 170m homogeneous at 700m. An 85mm homogeneous Panther glacis at 55 degrees from vertical would resist 122mm AP hits like 177mm vertical, which would result in a small percentage of 122mm AP hits at 700m succeeding. This is consistent with the reports on the initial combat between IS-2 and Panther, where penetrations at 600m and 700m were obtained with many ricochets (see Russian Battlefield article on IS-2 development).

The ARTKOM equation presented in Miles Krogfus' AFV News article on DeMarre and ARTKOM (May-Aug 2003) explains the basis for Russian penetration figures and calculated estimates. Some additional insights can be obtained through analysis of published Russian penetration figures for 76.2mm ammunition, which have been provided by Vasiliy Fofanov on Yahoo! Tankers forum site (with the same figures available on Russian Battlefield and other Internet sites). 76.2mm APBC BR-350A CP Penetration for 80% Success Probability 80mm at 100m, 76mm at 300m, 70mm at 500m and 63mm at 1000m 76.2mm APBC BR-350B CP Penetration for 80% Success Probability 86m at 100m, 81mm at 300m, 75mm at 500m and 68mm at 1000m Using the ARTKOM equation with the appropriate constants and shell factors from Miles' article, along with an assumed velocity-range curve, one obtains (80% success): 76.2mm BR-350A 75mm at 100m, 72mm at 300m, 68mm at 500m and 61mm at 1000m 76.2mm BR-350B 79mm at 100m, 76mm at 300m, 72mm at 500m and 64mm at 1000m The Russian firing tests for both rounds exceed the ARTKOM equation estimates by an average of 4.6% for BR-350A (range is 2.9% to 6.9%) and 6.5% for BR-350B (range is 4.2% to 8.9%). How to interpret the apparent variations? Miles' article indicated that production fluctuations could result in the penetration constant ranging from 2300 to 2500 for a round with an average constant of 2400 like BR-350B. If the Russian firing trials used 2300 constant ammo instead ot the typical or average 2400, the penetration estimates from the ARTKOM equation would be increased by 6.3%. One explanation is a random variation in the projectile "quality" used in the tests, where the guns fired above average rounds. Another possibility is the normalization of the ARTKOM equation, where the penetration of all rounds was forced to fit the DeMarre equation. If the actual relationship between penetration and velocity was different from the DeMarre equation, the 76.2mm APBC may have penetrated more than the equation predicted but a "one size fits all" equation may have glossed over some of the differences. Looking at 76.2mm APBC versus 85mm APBC, about 40% of the 76.2mm round diameter is "flat nose" as opposed to about 20% for 85mm APBC. Perhaps a wide flat or blunt area increases the face-hardened penetration. If the Russian firing test results are for 2400 constant ammo, the 76.2mm APBC BR-350B penetrates 75mm at 500m on 80% of the hits, or about 79mm at 500m on half the hits. So even at the higher test firing figures, 76.2mm APBC would not routinely penetrate an 80mm face-hardened plate. While the ARTKOM equation predicts 111mm at 500m, 102mm at 1000m 93mm at 1500m and 85mm at 2000m for 85mm APBC, the Russian firing tests resulted in: 105mm at 500m (ARTKOM estimate higher by 5.7%) 100mm at 1000m (higher by 2%) 92mm at 1500m (higher by 1%) 85mm at 2000m (no difference) Oddly enough, the 85mm AP penetration estimates from firing tests are very close to the figures for 85mm APBC at every range, suggesting that someone may have used the same velocity-range profile for 85mm AP and APBC.

Originally posted by Meach: "Some more questions tho. On an APCBC shell I take it the AP cap is under the ballistic cap as the ballistic is there to aid aerodynamics, yeah?" Yes. "And the AP cap is to absorb the sudden impact to allow the penetrator to do it's job, yeah?" Yes. Although armor piercing caps decrease penetration against homogeneous armor. "That means the penetrator had to be of the hardest material, the AP cap slightly softer and the ballistic cap was the softest metal of all? Please put me right on this." There was a wide range of armor piercing cap hardnesses, the German and Americans differed I think. The ballistic windscreen is a thin sheet metal that doesn't help or hinder penetration cause it crushes. "How did the shell "know" when to detonate upon penetration i.e a blunt nosed APBC with a high HE charge had to blow up at the right time to maximise damage, but how was this achieved?" The round has a given delay which couldn't have been very much if they exploded after passing through the spaced 20mm plate on the PzKpfw III front. There was about 8" (20 cm) of space to the main armor, I think. I'am not sure about the answer right now. "Was the British gun shells inclusive of the shell or was it just the projectile that was measured in the weight i.e 17 pdr, 2 pdr and so on?" The British used solid AP shot, then solid APC and solid APCBC. They took the HE burster out of American 75mm APCBC-HE and replaced it with an inert material (could be sand, not sure). British AP weights for the projectile (what comes out of the barrel) are: 2 pdr which is 40mm, 2.38 pounds 6 pdr which is 57mm, 6.28 pounds 17 pounder which is 76.2mm or 3", 17 pounds 25 pounder or 87.6mm, 25 pounds (I think, but could be 20 pounds, my mind is cloudy right now) 6 pdr APCBC weighed about 7.25 pounds, including main projectile, armor piercing cap and ballistic windscreen. 17 pounder APCBC total projectile weight was 17 pounds. [ May 03, 2003, 09:13 PM: Message edited by: rexford ]

This forum is not really the correct place to discuss this in depth so I will add one thing and leave the subject. When I fully referenced my posts on AFV News they were condemned as too long and tedious, and many folks told me to confine myself to summaries. When I summarized my work and left out the long and academic references it was condemned as being without any real support or usefulness. I am condemned for never changing my book and then condemned by the same people in the same post for changing it. The AFV News complaints appear to be more attitude than substance. Lorrin

Good post that is on topic. If my research ability, methods and emotional stability is questioned on another forum it is good to bring it out into the open on CMBB, given the amount of my work that has found its way into CMBB. Please see my response to Erickson's posts on the AFV News site. I have some theories regarding why my stuff is attacked so much, but that is something that shouldn't be aired in public. Thanks for bringing the AFV News discussion to my attention and to other readers on this forum. [ May 03, 2003, 12:04 PM: Message edited by: rexford ]

Those must have been the ones with bad plate. Perhaps the penetration figures in CMBB need a little decreasing for T34 APBC prior to late '43.

John Waters posted "In the April report the F-34 failed "even at 200 meters". The reports are Russian, conducted @ Kubinka & signed by Vorolov. Ranges were; as I have stated previously to you, & yes the F-34 & Zis-3 ammunition failed even @ 100m the angles used were 0 degrees - 30 degrees, & 60 degrees." That is new info to me and really is terrific, well it's terrific for Tiger fans and those we were looking for something concrete to compare against. So we finally have a range with an angle, T34 and 76.2mm field gun fails at 100m on 0, 30 and 60 degree hits. Thanks for the great new material. Can you share the source of the info, where you obtained it (a report from some dusty archives, a post on another forum, etc.). Your posts are really appreciated. Lorrin

John Waters posted the following: "Yet in the LF test report they state the F-34 could not defeat the Tigers side armor even at 200m. And the only gun reportedly that did penetrate the Tiger E armor was the M1939 85mm AA gun, which also reportedly penetrated the Tiger E armor frontaly @ 1000m. Yet in the Sept 43 tests 85mm obr.1941 AT gun could only defeat the Tiger E side armor @ 500m useing an "improved round" , and could not defeat the Tiger E on the frontal arc at any range. Also from both LF tests the 76.2mm Zis-3 could not defeat the side hull/turret armor @ any range or angle." I think the Sept. tests took place at an unspecified side angle. How much info do you have on the tests where 76.2mm fails against side at 200m and 85mm succeeds against front at 1000m? Do you have the side angle from firing weapon to hull facing, and do you have the ammo used (BR-350A vs BR-350B vs special BR-350B for 76.2mm, and BR-365 vs BR-365K for 85mm). Does the report say that 76.2mm could not defeat TIger side armor at any range or angle? What is the source of the Sept. 1943 report, is it Russian or German?