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I'm just wondering why the Super Pershing has a Slow ROF maker. I can't really see why it is slower. I'm assuming the gun fires the same shells as the short-barreled 90mm gun. Is this the case? I really doubt it is because of a 'cramped crew compartment' And the manuel stated that these are 2 reasons for a slow ROF marker.

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You can’t just slap on an extra 66 inches of barrel and let it sort itself smile.gif

A longer barrel almost always require a different round. If the weapon is well designed the size of the powder charge is finely tuned to the size of the barrel so that optimum pressure is achieved, neither too strong, nor too weak.

The T26E4 was at first armed with the T15 90mm gun. The rounds fire where some 50 inches long and quite a hassle to handle in the turret. This lead to the development of the T15E1 version of the gun. This later model fired two component ammunition, that is required separate loading of the projectile and the powder cartridge.

Hence the low ROF.

M.

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The original T33 AP round for the T15E1 was 50 inches long…cartridge plus penetrator. Because of the rounds excessive length, handling it within the turret of the “Super Pershing” was apparently very awkward. After some experimentation it was decided that the round would be produced as a two-piece round to ease handling. ROF of the “uber” T15E1 with two-piece ammo was apparently 4 rounds\min.

Ref: R.P. Hunnicutt, “Pershing, A History of the Medium Tank T20 Series”. Hunnicutt…except no substitute.

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<blockquote>quote:</font><hr>Crash Said: Also, Did later large-bore tanks like the Patton or M60 have this 2 part round?<hr></blockquote>

No.

Neither the M48A1(90mm) or the upgunned M48A5(105mm) used two piece ammo. APDS, HEAT and HEP were all single piece.

M60A1 also employed only single piece ammunition. APDS, HEAT and HEP were all single piece.

I think the 120mm on the M1a1 uses two piece ammo, but I am not sure on that.

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<blockquote>quote:</font><hr>Originally posted by Jeff Duquette:

I think the 120mm on the M1a1 uses two piece ammo, but I am not sure on that.<hr></blockquote>

It doesn't. It does however use combustible case ammo, which means there isn't a big brass case rolling around on the turret floor after it's fired.

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<blockquote>quote:</font><hr>Originally posted by panzerwerfer42 (talking about M1 Abrams 120mm rounds:

It does however use combustible case ammo, which means there isn't a big brass case rolling around on the turret floor after it's fired.<hr></blockquote>

From what I've read, combustible case ammo also means they can operate at higher barrel pressures without any extraction problems, i.e. there isn't any case to which might expand during firing and then get stuck in the barrel.

Edited to make more sense...

[ 10-30-2001: Message edited by: redeker ]</p>

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<blockquote>quote:</font><hr>Originally posted by redeker:

... combustible case ammo also means ... there isn't any case to which might expand during firing and then get stuck in the barrel.

<hr></blockquote>

Well, to a certain extent you want the cart case to expand. When the propellant detonates, the case expands and forms a tight seal inside the breech. This prevents any of the gas and pressure from leaking, and is known as obturation.

One of the reasons that brass is favoured for cart-cases is that its "soft enough for obturation, and stiff enough for extraction" ie, it forms good seals, and you can still pull it out after firing.

IIRC, the Germans were running low on brass by the end of the war, and fiddled about with other materials, but couldn't come up with anything nearly as good. Which isn't surprising given that we're still using brass 60 odd years later.

Er, sorry for the off-topic ramble. Please do not adjust your set. Regular scheduling will be resumed soon ;)

Jon

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I have seen Abrams rounds a few years ago and they seemed pretty one peice to me. Like any rifle round ever produced. Brass cases and all?? Usually "caseless" ammo has a very distinct look about it Like a ceramic jar or sometimes black...these were brass.

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<blockquote>quote:</font><hr>Originally posted by Crash-Neptune:

Also, Did later large-bore tanks like the Patton or M60 have this 2 part round?<hr></blockquote>

Stalins with their 122mm gun also had a two part round and this apparently was one of their major drawbacks vs Kingtiger.

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<blockquote>quote:</font><hr>Originally posted by JonS:

...IIRC, the Germans were running low on brass by the end of the war, and fiddled about with other materials, but couldn't come up with anything nearly as good. Which isn't surprising given that we're still using brass 60 odd years later...

Jon<hr></blockquote>

I believe that they used steel ammo casings for MG ammo when they started running low on brass. Of course, the steel tended to rust, causing frequent jams. MG42 crews would therefore try to keep a belt or two of brass cased ammo on hand for emergencies.

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<blockquote>quote:</font><hr>Originally posted by BsChoy:

I have seen Abrams rounds a few years ago and they seemed pretty one peice to me. Like any rifle round ever produced. Brass cases and all?? Usually "caseless" ammo has a very distinct look about it Like a ceramic jar or sometimes black...these were brass.<hr></blockquote>

Might have been 105mm from the earlier versions

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<blockquote>quote:</font><hr>Originally posted by machineman:

Stalins with their 122mm gun also had a two part round and this apparently was one of their major drawbacks vs Kingtiger.<hr></blockquote>

The early version of the Stalin also used a full screw breech which lengthened reload time even more. Their ROF was something like 1-2 rounds per minute. Later it was fixed with an interrupted screw breech or something like that which increased the ROF to 2-3 per minute.

I think I've seen steel casings on some rifle ammo lately. I fired off a box of Winchester Supreme ammo that had a shiny silver case.

[ 10-30-2001: Message edited by: panzerwerfer42 ]</p>

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<blockquote>quote:</font><hr>Originally posted by JonS:

hehehe - having a few problems with urls and images? ;)

I got the winchester link to work, and saw what you meant. I doubt if its steel - maybe an Aluminium or alluminium-alloy?<hr></blockquote>

7 edits worth. I finally gave up on them because they were around 100 characters long.. They might be aluminum because they weighed next to nothing after I fired them. They never had any ejection problems either on my semi-auto.

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