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Thompson 1921AC twist rate source?


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#1 poihths

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Posted 18 June 2019 - 05:28 PM

Hi! I need a published source, or at least a web page thats likely to be around for awhile, that states the design spec for the twist rate and twist handedness of the 1921 Thompson rifling. Any leads much appreciated!

Bob
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#2 thompsonteenager

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Posted 18 June 2019 - 07:40 PM

You gonna make the barrels now?
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#3 2ndArmored

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Posted 19 June 2019 - 09:53 AM

My records show a right-handed twist of 1:16

 

I'm really old.  How old?  This info came from one of my BOOKS - just like they had in ancient times!  So you're on your own for an enduring website.  (Gall dern new-fangled inty-net.  Grumble grumble.  Now git off mah lawn!)


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#4 thompsonteenager

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Posted 19 June 2019 - 10:16 AM

My records show a right-handed twist of 1:16

 

I'm really old.  How old?  This info came from one of my BOOKS - just like they had in ancient times!  So you're on your own for an enduring website.  (Gall dern new-fangled inty-net.  Grumble grumble.  Now git off mah lawn!)

what book?


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#5 Taliaferro

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Posted 19 June 2019 - 10:34 AM

See attached. I might help if you bought a book.

 

Tracie Hill

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#6 ron_brock

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Posted 19 June 2019 - 11:47 AM

https://www.amazon.c... thompso&sr=8-1

Ron
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#7 StrangeRanger

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Posted 19 June 2019 - 01:30 PM

My records show a right-handed twist of 1:16

 

I'm really old.  How old?  This info came from one of my BOOKS - just like they had in ancient times!  So you're on your own for an enduring website.  (Gall dern new-fangled inty-net.  Grumble grumble.  Now git off mah lawn!)

At the risk of quoting Jeff Cooper (the risk being that the kids have never heard of him and will have to look him up):

 

"The man who does not read possesses no particular advantage over the man who cannot read."


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#8 thirtyround

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Posted 19 June 2019 - 06:54 PM

BOOKS,  The Original Internet


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#9 reconbob

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Posted 19 June 2019 - 06:57 PM

  Out of curiousity is the twist rate for the M1921's the same as the military models?

The picture above is a U.S. Ordnance drawing, 

 

Bob


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#10 cbmott

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Posted 19 June 2019 - 07:06 PM

Definitely had to look up who Jeff Cooper was on that new-fangled internet device but his techniques/legacy are well known to me just not the name. I have many Thompson books, but I guess I’m still one of those young guys which is okay by me as most of my airmen who work for me were born in 2000-2001. Gents thanks for making me feel young again!
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#11 Grasshopper

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Posted 19 June 2019 - 08:14 PM

Hi All,

 

When in doubt get out a cleaning rod, brass button, and patch to fit the bore tightly.  Push the rod down the barrel watching rotation and distance.  Perform simple math.

 

or

 

What was it?  A book?

 

Grasshopper

 

ps.  I'm a fan of Ed McGivern at heart


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#12 Taliaferro

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Posted 20 June 2019 - 06:18 AM

Not much changed over time.

 

Tracie

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