Some Info I found on the Jackson

[user1000]

The M3 was also adapted as the main gun for various armored vehicles, starting with the experimental T7 which was accepted as the '''90 mm M3'''. The test firing of the M3 took place on an M10 tank destroyer+ in early 1943. The M3 gun was used on the M36 tank destroyer, and the T26 (later, M26) Pershing+ tank. Green, Michael, ''Tiger Tanks At War'', Zenith Press, ISBN 9780760331125, 076033112X (2008), pp. 118-122 The M3 fired a M82 APC shot with a muzzle velocity of 2,650 feet per second. However, both the muzzle velocity of the standard M3 gun and the quality of the steel used in the M82 APC shot were inferior to the KwK 43 L/71 88 mm main gun firing its standard APCBC shot used by German forces, with the result that the former's penetration fell far short of the standard projectile fired by the KwK 43 German 88 mm used on the Tiger II/King Tiger tank. As a result, U.S. ordnance provided some T26/M26 tank crews with the 90 mm HVAP (high-velocity, armor-piercing) tungsten penetrator sub-caliber projectile with a muzzle velocity of 3,350 feet per second, or the T33 AP with a re-heat-treated projectile with ballistic windshield and a muzzle velocity of 2,800 feet per second. ''Armor-Piercing Ammunition for Gun, 90-mm, M3'', Washington, D.C., U.S. Army: Office of the Chief of Ordnance (January 1945) The HVAP could compete with the KwK 43's penetration performance when firing std. APCBC, but tungsten ammunition was always in short supply, and the T33 which only just made it in service a month before the end of the war still fell far short of the KwK 43's performance.

An unsuccessful anti-tank variant was the T8 gun on the T5 carriage. The gun was an M1 with the recoil mechanism from the M2A1 105 mm howitzer+. Eventually a version of the T8 with the T20E1 gun and T15 carriage was tested; this led to the 105 mm anti-tank gun T8+.

Because the standard fifteen-and-a-half foot long M3 90 mm main tank gun proved incapable of penetrating the heaviest frontal armor of the heaviest German tanks such as the Tiger II/King Tiger tanks and their seldom-seen ''Jagdtiger+'' tank destroyer variant, a number of improved versions of the M3 were developed, including the T14 which included a standard muzzle brake+ and the T15 series. The 21-foot long T15E1 90 mm main gun fired AP T43 shot with an initial muzzle velocity+ of about per second, later increased to per second. Two M26A1E2 "Super Pershing" tanks were equipped with T15-series 90 mm main guns in March 1945. One of these tanks, equipped with a 90 mm caliber T15E1 high-velocity gun firing an AP shot at per second made it to the European Theater of Operations and was assigned to the 3rd Armored Division for the testing purposes. Firing HVAP this gun could penetrate 8.5 in (220 mm) of rolled homogeneous armor (RHA) at a range of 1,000 yd (914 m).

Near the end of World War II, more experimental versions of the 90 mm gun were tested, including the T15E2 and the even higher velocity T18 and T19 main guns. The T19 was a T18 modified in an attempt to reduce barrel wear. Other versions included the T21, which was intended for wheeled vehicles, and the T22, which used the breech from the standard 105 mm M2+ howitzer. The T21 and T22 were designed to use larger powder charges. None of these versions entered service.

[John Kettler]

user1000,

Most interesting, but it would be helpful if the MVs were in the text. Rather jarring read as is.

Regards,

John Kettler

[Michael Emrys]

10 hours ago, user1000 said:

105 mm anti-tank gun T8+

Hmmm. This looks like the gun that rested on the quad of my high school back in the late-'50s-early-'60s. I've tried for years to identify that gun with no previous success. The gunshield on this on this one does not look quite as I remember it, but the gun is limbered in this photo which would change the look in various ways. The muzzle brake is the first one I have seen on an AT gun that looks like the one in my past. Interesting. If this is the gun, and as the text says only two copies were made, I have to wonder how my school ended up with one of them. I also wonder where it is now.

Michael

[user1000]

^ yeah strange huh. I knew about the 105 howitzer but, I never even knew there was a 105mm AT gun - says it never saw combat in Europe.

Edited April 16, 2016 by user1000

[Michael Emrys]

26 minutes ago, user1000 said:

...says it never saw combat in Europe.

And only two examples were built.

Michael

[panzersaurkrautwerfer]

8 hours ago, Michael Emrys said:

Hmmm. This looks like the gun that rested on the quad of my high school back in the late-'50s-early-'60s. I've tried for years to identify that gun with no previous success. The gunshield on this on this one does not look quite as I remember it, but the gun is limbered in this photo which would change the look in various ways. The muzzle brake is the first one I have seen on an AT gun that looks like the one in my past. Interesting. If this is the gun, and as the text says only two copies were made, I have to wonder how my school ended up with one of them. I also wonder where it is now.

Michael

Odd where that all shows up.  I always have a sort of finding a lost Inca pyramid reaction when I find something rare like that, usually followed by the disappointment of being the only one in the immediate area that cares.

There really ought to be a German word to describe that feeling.  

[A co]

Kanonenfinderseinsamkeit

[fivefivesix]

1 hour ago, A co said:

Kanonenfinderseinsamkeit

Thats the nice thing about German, you can just mash together existing words until you have a new one that fits your intended meaning. 

[Michael Emrys]

12 hours ago, panzersaurkrautwerfer said:

Odd where that all shows up.  I always have a sort of finding a lost Inca pyramid reaction when I find something rare like that, usually followed by the disappointment of being the only one in the immediate area that cares.

Many years ago I spent several days in Hollywood, Oregon (a suburb of Portland), and one afternoon was walking around and passed the National Guard Armory and there sitting on a concrete pedestal was an early-WW II 37mm AT gun. I immediately recognized it from photographs and so knew what a find that was.

Michael