rexford

The gun that fired into another turret on the same vehicle did so against a moving target, it tracked the target, moved out ahead of the target to obtain a lead and fired into the adjacent turret, or so the story goes.

There may have been three hulls welded together to hold the three turrets. Next time I go to the hobby shop I'll see if they gave a good reference document. Funny that no one, German or Russian took pictures or brought it home of rshow-'n-tell. The tank did not move very fast, but, if one believes the write-up with the model, Stalin believed it could stop panzer divisions for days.

Advanced Squad Leader states that U.S. 37mm cannister is available on all fronts after July 1942. 75mm U.S. cannister available 44-45 but not in Italy. 105mm U.S. cannister 44-45 but only in Pacific. ASL gives 37mm cannister fair availability, 58% chance it is there first time gunner reaches for it.

Claus B. Thanks for noting 1000 yard limit on APDS use, somehow I didn't notice this. This range limitation was in 6 and 17 pdr manuals for APDS during WW II? When British test fired 6 pounder APDS against a captured Tiger during 1945, they had no problem saying round would penetrate beyond 1000 yards. The fact that they tested APDS with impact velocities expected beyond 1000 yards suggested that APDS could be used at any range. We thought the use of 1000+ yard velocities in penetration tests meant that APDS could be used beyond that range.

The Albany, NY Hobbytown has a scale model of a KV tank that Stalin supposedly had built after panzers were delayed by individual KV-1 and KV-2 behemoths. This is the story that goes with the model: The Stalin concept tank had two KV hulls welded together and three KV turrets. One turret had two 152mm guns, one had a flamethrower and two 76.2mm guns and the third had rockets on top and some guns in the turret. Three of these were built. The first saw combat and one of the turrets fired into another turret. One super KV down. The second super KV hull cracked as it went over a depression and burned. Two down. The third super KV had all three guns simultaneously fire at flank targets on the same side, the tank rolled over and burned. Super KV designers spent rest of war in Siberian camps. They forgot normal devices that do not allow turrets to fire into each other or to all fire broadsides at same time. Is this real or make believe, you decide.

Robert Livingston advised me that U.S. gunners were given cards for HVAP use that identified range scale settings to be used, and they seem to have worked well since 76mm HVAP was one of the most accurate projectiles of WW II, if not the most accurate. 90mm HVAP users also seemed quite happy with accuracy. We have a British report where 76mm HVAP is noted as having the smallest scatter about aim point of any WW II ammo, even better than 76mm APCBC which had been the best. And 76mm HVAP did not throw off accuracy of later shots with APCBC. Inconsistent APDS performance from Firefly was probably accepted as the price to pay for superior APCBC performance against Tiger front and Panther mantlet. Good points Conall.

Thanks Conall for authoritative and well documented analysis of 17 pounder problems firing APDS. It looks like it would be natural for a high percentage of APDS shots to have reduced accuracy and penetration, due to 17 pdr muzzle brake and sabot shed problems. Our booklet will analyze the percentage of 17 pounder APDS shots that perform as if problems did not exist. CM should do something about APDS from 17 pounder if game is to be realistic, which includes decreasing the slope effect when the ammo is working correctly (however often that may be).

To cover all the bases, did American sights have specific range lines for 76mm and 90mm HVAP? Is it safe to assume that U.S. 57mm ATG didn't have sights for APDS? This might account for some of the inaccuracy noted in firing tests against Panther with 57mm M1 gun. Using APCBC range lines for APDS shots against moving targets could also result in misses if gunner forgets to take percentage of APCBC lead. Too much lead for speedy APDS. Looks like Conall's post has opened up a new and valuable "can of worms". And, of course, how many Stuarts and 2 pounder equipped AFV had range sights graduated for Littlejohn adaptor? Tungsten is great if sights include it.

Here' some stuff on 17 pounder APCBC and APDS against angled targets at 500m and 1000m: ----------------------------------------- 80mm Panther glacis plate at 55 degrees, 0.93 quality due to flaws (this is quality when 76.2mm hits 80mm plate at 55 degrees for medium severity flaws or brittleness) APCBC can't penetrate APDS penetrates at 1700m ----------------------------------------- 85mm Panther glacis plate at 55 degrees, 0.93 quality due to flaws APCBC is no good APDS penetrates at 1300m ----------------------------------------- 80mm Panther glacis plate at 55 degrees, 1.00 quality due to absence of flaws (which occurs about half the time, maybe) APCBC bounces all the time APDS penetrates at 1300m ----------------------------------------- 85mm Panther glacis at 55 degrees, 1.00 quality APCBC is useless APDS penetrates at 1000m ----------------------------------------- APDS fails to penetrate Panther glacis at Isigny due to the sabot problems, which is clear when one looks at the trouble they had hitting what they were aiming at. My analysis of what happens when half of APCBC range scale is used for 17 Pdr APDS shows that absence of range lines for APDS should not throw off Isigny shots by enough to explain the bad showing. The ranges vary from 200 yards to 800 yards. APDS at Isigny was striking Panther glacis with enough yaw angle to destroy penetration even if it could hit, it would seem. Many Russian, American and British sources list Panther glacis at 85mm thickness, and Panther nose at 60mm to 75mm. Actual measurements on nose armor show that it exceeded the usual assumed thickness of 60mm by over 10% (see Isigny firing test report). As war carried on, quality control may have allowed over-thickness plates for one reason or another to speed production, reduce number of plates disallowed for too much thickness, etc. 85mm Panther glacis explains alot of firing test and battlefield reports. Plate is 6.3% thicker than 80mm, and slope effect will be larger, and quality will be larger even with flaws (due to T/D ratio), so 85mm glacis is alot more resistant than 80mm.

Thanks for valuable info on actual procedure used to fire APDS using APCBC range scale. Did an analysis of what it means to use half of the APCBC setting when it should be 0.555, a 10% error. Sounds small and insignificant, but...... APDS MPI (MEAN POINT OF IMPACT) error due to "make believe" range scale (take half of APCBC): 500m 10% angle error throws mean trajectory off aim point by 0.1m 800m 10% angle error results in 0.3m error 1100m 10% angle error puts mean point of impact 0.5m away from aim point 1400m 10% angle error is associated with 0.8m error Now this is the impact if the range was perfectly known to the target, which it isn't. There is also shot scatter based on other random factors. If APCBC results in a hit at 1500m on the Tiger II turret center, for instance, and the gunner then switches to APDS to kill the beast, first shot aim will be off by about 1m vertical. This is enough to greatly increase the percentage of APDS shots that miss the target on the first shot. Since APDS isn't too abundant and about half the shots have that nasty habit of missing anything and everything due to sabot problems, and won't pierce even if they hit, first shots at 1500m will be a waste of ammo alot of the time. I wonder if scenario's like this resulted in orders to only use APDS at short and medium ranges during WW II. Even after the war with better APDS and solutions to other APDS problems, trying to get by using half the reading on APCBC scale greatly reduces first shot accuracy with expensive ammo. Regarding German accuracy relative to British, British documents state that using APDS reduces accuracy of following attempts with APCBC, something that does not happen with HVAP. And British gun sights could go out of alignment due to recoil, and they wonder if German sights are similar. And there are notes that German sights are superior to American/British cause they are more accurate and work better in dim light/overcast conditions/days without bright sunshine. And so on and so on. Given equal range estimation and round to round scatter, all of this suggests that Tiger hit probability could be higher than 17 pounder APCBC at range due to better sights, and no APDS that messes up sights. Better sights give Germans an advantage in terms of hit % on first shot and follow-up. Sorry to say this in terms of Firefly survival, but it seems to be true. We can theoretically calculate hit % based on trajectory and dispersion and range estimation error, but it is all garbage if gunsight limitations and problems are not cranked into the equation. Another advantage to panzers.

For those who have accused me of blatant German bias in the past, my dresser is the proud home of TEN (10) Matchbox 1/76 scale Fireflies. Was going to cut down the barrels on most of them to make 75mm L40 Shermans, but that would be sacrilegious. Matchbox Fireflies are not only good against Matchbox Panthers when APDS is flying right, but 17 pounder can pound the tar out of Matchbox JagdPanzer IV with 80mm armor. Matchbox 1/76 scale is cheap and easy to obtain, compared to fujimi which almost costs three times as much. And Matchbox 17 pounder APCBC doesn't self-destruct after it penetrates spaced armor on M.B. PzKpfw III, cause it is solid shot. By numbering my Fireflies, German players don't know which is the real 17 pounder and which is a 75mm "door knocker". So there!

My just posted posts forgot to belabor the well worn party line: APDS slope effect at 60 degrees is 3.54, not the 5.00 that CM uses. APDS done properly can kill a Panther or JagdPanther thru the glacis at 700 yards or greater, which CM may not be able to duplicate at present. Good performing APDS is a gem, worth wading thru all the bad sabots and missing gun sight lines and in-the-way muzzle brakes and everything else. Firefly APDS fans demand better slope effects, reduced dependability and less accurate sabot!!!! This way it's exciting like Las Vegas, where one loses miserably or wins like a million!

Good post Jeff! Showing that scope view really added a missing dimension to the thread.

Computed the gun elevation angles for 17 pounder APCBC and APDS against targets at 500, 800, 1100 and 1400 meters. In all four cases, APDS gun elevation angle is about 55% of APCBC. If this ratio was known by authorities (good likelihood), and was given to Firefly crews (good chance), crews in field might be able to correct for absence of APDS lines by roughly "halving" APCBC elevation. This subject does require more info on exactly what was done to properly aim APDS.

Jentz' Tiger book has some tests where 6 pdr APDS fired against Tiger during 1945. There are a number of cases where penetration is alot larger than armor resistance, which suggests bad trajectory (yaw angle) throws off penetration. From page 17: 1. 6 pdr APDS should penetrate 127mm at 24 degrees and 3390 fps, it fails against 102mm at 24 degrees. 2. 6 pdr APDS should penetrate 123mm at 30 degrees and 3507 fps, it fails against 82mm at 30 degrees with a Panther track attached. 3. 6 pdr APDS should penetrate 142mm at 24 degrees and 3665 fps, it fails against 102mm at 24 degrees with a Panther track attached. There are a few more cases that suggest bad APDS ammo trajectory, and this is a March 1945 test. As Conall pointed out, sabots banged against muzzle brake as round left barrel or sabots clung too long on one side, throwing round off its' path. Throw in gun sights that went out of adjustment or didn't have APDS calibration and things keep getting worse. How many rulesets out there treat WW II APDS as a "hit or miss" (in literal sense) ammo. None that we can find. In our miniatures rules we throw a dice for APDS, and on about half the rolls the ammo is useless. But like I said in previous post, half a loaf is better than none against Panthers, Tiger II's and JagdPanthers. To do WW II right, one needs randomizing rolls for APDS usefulness, Panther glacis armor quality, etc.

If none of the gunsights used with APDS is calibrated for the ammo, this makes APDS even less accurate than it might be when the sabots work as designed!!!!!!!!!!!!!! APDS is looking less and less accurate. Would British tanks want to use APDS instead of APCBC? 1. APCBC can't dent Tiger II turret front, APDS can and should pierce on most hits (IF it works properly) 2. APCBC may shatter against Tiger mantlet or fail to penetrate very thick areas, APDS would have alot less trouble, if any 3. APCBC cannot penetrate Panther or JagdPanther glacis at point blank, APDS that works like it should can, and out to 700 yards or more. APDS designed to attack and penetrate thick armor that APCBC self destructs against. Even if half the APDS is poor and doesn't work well, half a chance is better than none. With regard to gun elevation, if APCBC at 2900 fps requires 5 mils elevation, APDS at nearly 4000 fps could be assumed to be a certain percentage of APCBC angle. Was reading about the many ways British camouflaged or tried to hide Firefly barrel so Germans wouldn't pick out tank for rapid elimination. Like phoney muzzle brakes halfway down barrel and the like. How come Germans in CM pick out my Fireflies right away at all sorts of ranges and volley fire at the 17 pounder tank. A Firefly at 700m range, facing directly at a Panther, isn't that different from a 75mm Sherman. If Germans can spot 17 pounder tanks that quick then APDS becomes a moot point when British attack.

The booklet we are going to publish goes into the problem of compound angles, which is what is required when a vertical angle is combined with a lateral angle. Panther 55 degree glacis might be hit at 15 degrees from straight-ahead, which represents a 56.4 degree compound angle. Slope effects are then computed on the basis of T/D and compound angle. It turns out that the steeper the vertical slope the less effect from lateral angles. Advanced Squad Leader rulebook does not have any HE for 2 pounder gun. What is really interesting is that 28/20 German squeezebore anti-tank gun does have an HE shell. 20mm HE sounds real intimidating, like German 20mm APCR. Tungsten core must have been less than 1/2 inch wide. Brits say that littlejohn cores for 37mm and 2 pounder were around 18mm wide, which is around 3/4 inch. 37mm gun on Stuart had HE. Advanced Squad Leader doesn't appear to have Littlejohn squeezebore adaptors for 37mm and 2 pounder guns, so they did miss some "important" things. 57mm Soviet anti-tank gun, alias "the hunter", fired AP and APBC at over 3000 fps, which we believe is responsible for many recorded close range hits on Tiger with few penetrations. At 3000 fps and over, 57mm rounds with low nose hardness are bound to shatter on 80mm and 100mm thick armor (ye olde shatter gap). U.S. studies predict that square nose rounds, like Soviet 57mm APBC, are even more prone to shatter failure than normal AP, since nose stresses are greater on low angle hits against armor when T/D is greater than 1.00.

I'am sure BTS will eventually model APDS with random variations from poor to good, even if only two states. Based on high velocity of round, APDS should be much more accurate than 17 pounder APCBC. At Isigny, APDS hits target area about 55% of time, 17 pounder about 85%. APDS fails to even hit target at ranges where errors in gun sight use should still land shot on target. Penetration tests against Tiger show about 40% of APDS doesn't penetrate what it should, probably a yaw related problem. Other American tests note inability to hit target on many shots. All of this suggests at least 40% of APDS rounds with reduced accuracy and almost no penetration capability due to yaw angle (hitting something with a sideways moving round just doesn't cut it). Subject to further study, it might be reasonable to assume that 40% to 50% of APDS is near useless, due to yaw. We have enough data to refine this figure but don't have time at present. Conall's info suggests problems that couldn't be addressed without redesigning APDS and removing muzzle brakes, which didnt occur. WRG wargame rules for miniatures made a statement that accurate/effective APDS was a post-WW II development. Most interesting tungsten use was Littlejohn adaptor, placed on 2 pounder and 37mm light tanks/armored cars, that theoretically allowed penetration of Tiger front hull at close range. I believe Littlejohn used squeeze bore teck-nolo-gee, and no other rounds could be fired with adaptor on gun (was there squeezebore HE?). Can CM tanks and armo cars use Littlejohn adaptor? Further threats to poor old PzKpfw IVH, little tanks and armored cars running around shooting tungsten rounds with over 100mm penetration at close range. Wonder if a penetration would be noted if round didn't hit anyone, due to small size and fact that tungsten rounds may break up during penetration (or so I read somewhere, although test firing against Tiger in Jentz shows APDS holding together after it penetrates 80mm armor).

Asked for help on other sites regarding APDS problem causes, here is what I received from Conall(references to follow): 1. APDS disrupted by muzzle brake interference with discarding sabots 2. Uneven discarding of sabots (YEAH! I is vindicated) 3. Bad ammo production during early stages 4. Poor type of discarding sabot on British APDS, different from model that eventually lead to uniform performance 5. Gun sight wasn't designed for APDS ranging CM really needs to model APDS inconsistency in terms of accuracy/penetration. Anything less is just not realistic. Once in a while APDS works like design, other times it doesn't. Our booklet will present enough data to estimate good/bad percentages. And while they are at it, change the tungsten slope effects so they are in line with published test results (60 degree slope multipliers of 3.5 for APDS, 4.4 for HVAP), instead of home-brew concoction of 5.0 in CM. If CM crew is dedicated to quality, the inconsistent quality and true slope effect of APDS should be addressed.

Came across some material on WW II APDS, associated accuracy problems with disturbances caused by sabot shedding, did not add anything else. Achilles added weight to barrel for reasons other than APDS accuracy.

Oooops! Meant to say off-center core placement in previous post. Insufficient sleep will do you in every time.

Previous posts on this site referred to studies showing that sabot shed was not the problem with accuracy/penetration, it was off-center sabot placement. And that weight on Achilles barrel helped solve APDS problems. Would appreciate references for these statements. Thanks.

There is a book written by a famous GrossDeutschland vet that describes a large scale Soviet infantry attack where Soviet "asians" were sent into the assault without weapons! Infantry were running towards the German lines without guns! The author described them as Asians because that is what he observed. Not a fairy tale at all, and not Georgians. Tanks do fight tanks. Panther formations fought large groups of IS-2m's, panzers fought Russian tank formations (read Jentz's books). Kursk, where T70's on one hill fought panzers on another. El Alamein. Tobruk. The fairy tale is that tanks don't fight tanks, which is a completely short-sided view. One Panther is worth more than five T34 if they come out one or two at a time facing the Panther, or all come out at once at 2000m. One Panther is worth at least three Sherman if the Panther jumps out and suprises the enemy at 100m, and starts shooting, before they can maneuver. Barkmann's corner. A PzKpfw IVH would not have survived as well. If tanks meet and there aren't any anti-tank guns or mines or infantry with bazooka, what I said holds. Tank comparisons depend on specific situations. Panzers trying to stop a Sherman breakthrough at short range, or a horde of T34's at long range, is likely to represent tank-vs-tank combat. Tank-vs-tank isn't a high percentage of tank losses but it is size-a-bull. When people hear stuff that is contrary to their own fairy tales, they call it names such as a "fairy tale".

Thanks for armor type responses. Question on Pershing hull is on the mark, Pershing hull front was cast, as was turret. If a tank has cast and rolled armor but the primary area (hull front) is cast, tanks like Pershing and M4A1(76)W should get cast deficiency multipliers. 0.85 for M4A1(76)W (51mm armor against 75mm and 88mm hits), a little better for Pershing since it overmatches 75mm and 88mm hits. However, it would seem that each armor area should get treated separately, since hull front may be cast but turret front/mantlet could be rolled. Did CM treat Pershing and M4A1(76)W hull front as cast or rolled, or is CM program based on 1 armor quality for an entire tank, which is why Panther gets 0.85 for all armor even if glacis was only consistently flawed area. Maybe CM can't accept random quality choices so every Panther is flawed, and every 17 Pounder APDS shot meets penetration and accuracy bests, even though about half of Panthers and APDS shots might be up okay and the rest deficient. M4A1(76)W front hull and turret front would be easy pickings for 50mm Pak at close range.

Was the front hull on the subject tank cast? Asking this question because 2" cast armor hit by 75mm rounds should have a 0.85 armor quality multiplier due to cast deficiency, even if no flaws. Does CM apply cast deficiency multipliers?