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View Full Version : why do thompson's have to have such long receivers?


ledslinger
06-22-2012, 6:51 PM
seems like it adds weight and loses maneuverability.

do they fire from bolt open?

would it be possible to machine a shorter receiver on a semi auto build?

has anyone done this?

ojisan
06-22-2012, 7:01 PM
1. Room for the bolt to move back, return springs, room for the hammer to swing, it has the stock latch inside, too.
Older design, full auto needs a heavier base to fire from than semi.

2. Full auto oldies and military autos fire from an open bolt. The current semi-autos sold by Auto Ordnance fire from a closed bolt.

3. Complex design, it's tough to shorten. Auto Ordnance makes a lighter version with an aluminum receiver.

4. Somebody somewhere has done most everything. There are other designs of "tommy guns" out there...but much shorter internally I don't think so. It's up to you to re-engineer it with modern materials and production capabilities.

TKM
06-22-2012, 7:05 PM
1920s technology, open bolt too.

Back then, the .45acp was a very powerful round.


Basically the Thompson was a blowback operated weapon. Initially it used something called the Blish Principle to delay the action but it turned out to be un-necessary and overly complicated.

I've fired both the Thompson and a 45 caliber M16, the "La France M-16K" . There is a lot to be said for modern firearms.

Might not be all Walnut and Blued Steel, but they surely work.

MrPlink
06-22-2012, 7:57 PM
plenty of other firearms in 45acp if you want something more modern.

ACRfan
06-22-2012, 8:12 PM
Get a USC

winnre
06-22-2012, 8:32 PM
I'm 6'4" and the Thompson pushes me backwards on full auto. Yes it is only a 45 but you can feel the power. Video here: http://www.youtube.com/watch?v=Luw7dN-cT-0

And a buddy: http://www.youtube.com/watch?feature=endscreen&v=l4B1msDN-lE&NR=1

G-forceJunkie
06-22-2012, 9:10 PM
Have you seen how big and heavy a Thompson bolt is to work in a blowback configuration? We are talking pounds of steel.

Richard Erichsen
06-22-2012, 10:22 PM
There is, if I recall, more recoil energy from the .45 ACP than the 5.56 NATO or .223.

I've always favored the simplicity of the M3 Greasegun which has a long receiver for the same reason all recoil operated full auto firearms operating from the open bolt do, but without much of the costly machined receiver components or added mass. Despite the spot welded sheet metal construction, M3s were able to put more hits on target than the heavier M1928 and later "M1". Good stuff. Ugly as sin though by comparison to the handsome pre-war and early WWII Thompsons.

R

redcliff
06-23-2012, 8:08 AM
I'm 6'4" and the Thompson pushes me backwards on full auto. Yes it is only a 45 but you can feel the power. Video here: http://www.youtube.com/watch?v=Luw7dN-cT-0

And a buddy: http://www.youtube.com/watch?feature=endscreen&v=l4B1msDN-lE&NR=1

While I'm sure you and your buddy are very good shooters, when shooting submachine guns bend your knees and at the waist and lean into the weapon and keep your elbows down. ;)

There is, if I recall, more recoil energy from the .45 ACP than the 5.56 NATO or .223.

I've always favored the simplicity of the M3 Greasegun which has a long receiver for the same reason all recoil operated full auto firearms operating from the open bolt do, but without much of the costly machined receiver components or added mass. Despite the spot welded sheet metal construction, M3s were able to put more hits on target than the heavier M1928 and later "M1". Good stuff. Ugly as sin though by comparison to the handsome pre-war and early WWII Thompsons.

R

Unless they have a telescoping bolt like a Mac10 or Uzi, etc..

winnre
06-25-2012, 7:59 AM
While I'm sure you and your buddy are very good shooters, when shooting submachine guns bend your knees and at the waist and lean into the weapon and keep your elbows down. ;)


All SMGs I shot before have better recoil control. Heck the M16 I can fire with one hand and the M60 has enough weight on it to behave itself. Different stances and attitudes are definitely needed with these other toys.

bohoki
06-25-2012, 9:56 AM
durability,recoil reduction