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Tsmg Bolt Question


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#1 AZDoug

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Posted 03 February 2004 - 03:10 AM

Why were there two sear catches in teh bottom of the 1921/28 bolt?

I have pondered this for some years (off and on, I really do have other things to do) :-)

And have come to the following conclusion: The rear (stock end) most catch is for general manual cocking so the bolt doesn't have to be pulled all the way back, and the front most catch is for the first chance to stop multiple discharge after the trigger is released, the then the rear catch acts as a safety catch for either bounces off the buffer the for underpowered ammo.

Does anyone have the real story?


BTW: You guys that hate NAC guns so much remind me of a family reunion at the DuPonts when all of a sudden some mixed race orphan shows up and claims she is heir to the fortune. laugh.gif

Doug
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#2 Arthur Fliegenheimer

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Posted 03 February 2004 - 08:44 AM

Doug,
I think you have hatred confused with incredulity. When Philip Fetcher creates a myth about NAC Thompsons' to justify a $20K to $25K projected JC Devine auction price, the uninitiated collector might drink that Kool-ade before taking a closer inspection. As far as the hillbilly relative reference, it seems Fetcher is trying to stake a claim for the entire inheritance before the demise of the patriarch.

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#3 AZDoug

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Posted 03 February 2004 - 12:27 PM

Hey, what fun is it if I can't pull y'alls strings about NAC guns. biggrin.gif I know nobody here hates them, they are just the red-headed step child of the family.

I am curious if anybody has the exact why and wherefore of the two sear catches on the bottom of the bolt.

Another question or two: Did the original Colt 1928 buffer pilots have the little hole at the front so a pin could be inserted to keep the spring compressed over the pilot during reassembly, or is that a WWII introduction?

Doug
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#4 21 smoker

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Posted 03 February 2004 - 12:44 PM

AZDoug,...all the 28 buffer pins I have seen have the hole... I thought the 2nd sear slot was on Brit proofed stuff...only guessing on that.out.
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#5 The1930sRust

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Posted 03 February 2004 - 01:13 PM

QUOTE (PK. @ Jan 19 2004, 10:24 PM)
There are two notches in either the 21/28 or M1/A1 bolts (towards the front of the rectangular body) which will hold the bolt in the cocked position, one a little further back than the other. The “first” notch catches the bolt in the rear most position. The “second” notch is about 5/8” back of the first and will allow the bolt to be that much further forward when cocked. It’s purpose is to catch the sear if the first notch misses it in semi auto fire.

The third notch in the M1/A1 bolt (towards the rear of the bolt) allows the sear to raise up so the safety can be engaged with the bolt closed.
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#6 mp40

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Posted 03 February 2004 - 09:23 PM

Guys, Not having a Thompson here in my hands to check it out, but..Does the bolt face clear the top round in the magazine before the sear catches the first or second notch? if it does, perhaps, it might act as a safety in the case of cold wet hands actuating the bolt, slipping just after the bolt face clears the round in the magazine... Accidental discharge time....Could this be the case? I know that this is the case in many other open-bolt firing designs.
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#7 John Jr

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Posted 03 February 2004 - 09:43 PM

I dont give a nac! biggrin.gif

Mine shoots from both positions. Who knows why its there, PK's answer is probably about a close as your going to get. Call Doug Richardson, I bet he knows more than I do.

Jr

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#8 PK.

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Posted 04 February 2004 - 03:00 PM

The sear would have to engage the bolt prior to the bolt face engaging the top rd in the magazine in order to prevent an accidental discharge as you describe. This is not the case with the Thompson.
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