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Rate Of Fire M1 Vs M1a1


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#1 JTinIN

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Posted 13 November 2004 - 11:07 PM

Was shooting a friends posty M1 today (good use of a parts kit smile.gif

and had heard that switching to a M1A1 bolt would slow down the rate of rife. Had read the first round of M1's had waited on a waiver for having a faster rate of fire than the specified, however, was not sure if this was one time issue or part of the design of the M1s.

Will dropping in a M1A1 bolt, slow down the rate of fire ... to notice?

Edited by JTinIN, 13 November 2004 - 11:08 PM.

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#2 PK.

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Posted 13 November 2004 - 11:09 PM

"Will dropping in a M1A1 bolt, slow down the rate of fire ... to notice?"

Yes

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#3 tcgoll

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Posted 13 November 2004 - 11:44 PM

My Bridgeport M1 using 230 hardball was timed at 853rpm. Another person with a Bridgeport M1A1 timed at 747rpm with the same ammo. Hope this helps.
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#4 JTinIN

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Posted 14 November 2004 - 11:04 AM

Thanks!

Now the question to ask is it work what every small risk there is in having an early round fire when using the M1A1 bolt?

(On the posty ... answer is yes ... on my transferable M1 ....????).

Edited by JTinIN, 14 November 2004 - 11:05 AM.

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#5 TSMGguy

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Posted 14 November 2004 - 01:17 PM

"Is there a danger that a round will fire before a M1A1 bolt is fully in battery" is a question expressed many times on the boards. The problem appearently did not exist during the war, or if it did, I can't find references to it or to any fixes. When GI guns went through ordnance level overhauls, the M1 bolt was most often replaced with an M1A1 bolt, and the new nomenclature was generally stamped on the side of the gun. This fix also served to slow the rate of fire by about 100rpm which was seen as desirable at the time.

I think most collectors go in the opposite direction, finding and installing a M1 bolt, for the faster cyclic rate and for a perceived added safety factor.

On chambering, the bolt initially engages only the top of the cartridge, pushing it toward the breech. The cartridge base is free to enter the firing pin indentation in the M1A1 bolt face in only the last fraction of an inch before seating fully.

I conducted a little informal experimentation along these lines. I loaded a single fired case into the chamber of my M1 with a USGI M1A1 bolt fitted. I then loaded a magazine with single rounds that were complete except that they contained no powder. I was trying as best I could to simulate a failure to extract. On each of many tries, the bulleted rounds (I made and tried several) would of course jam between the bolt face and the chambered case, but always did so with the base of the fresh "round" well away from the firing pin indentation.

Having said all of that, since I shoot left handed, I still go with the M1 bolt, as you can't be too careful when you face is fully exposed to a TSMG breech! I also think that the "bright" M1 bolt looks way cool in the gun.

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#6 JTinIN

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Posted 14 November 2004 - 02:23 PM

Thanks

One of the guys I shoot with had part of the brass case left in the chamber and was glad he was using the M1 bolt ... as the way he was thinking was that when the loaded round hit the brass ring for the last case front, then the loaded round would have gone off with a M1A1 bolt.

Regards
John

P.S. For shooting left handed one could make a case to trade the M1 for a 1928A1 or such.
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#7 Hawkeye_Joe

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Posted 14 November 2004 - 03:29 PM

QUOTE
For shooting left handed one could make a case to trade the M1 for a 1928A1 or such.


The ejection port is still on the right side...so changing to a '28 would make no difference..
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#8 JTinIN

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Posted 14 November 2004 - 04:38 PM

Only thing to gain on the '28 is the area of the slot for the charging handle, which agree is very slight (bit don't need much of a reason to get a '28 smile.gif
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