Ez-pull Springs, Lightweight 1927a Semis, And Buffers

[nfafan]

Hello all,

 

Been away from the board for awhile and in trying to catch up on readings I found some posts hinting that the EZ-Pull Springs are no good for the aluminum lightweight guns.

 

What seems to be the reasons?

 

Admittedly I do not have many rounds thru my 1927A1C, but the EZ-Pulls made it a joy to take to the range and I've seen no issues. I installed it according to instructions, which called for placing the included thick buffer between where the bolt and back of the spring retainer plate would slam together.

 

Would it make sense to alld a thin piece of buffer material - like a piece of leather that I've read about - between the spring back plate and the back inner wall of the upper receiver?

 

Thanks!

Steve in PGH

[reconbob]

Your worst case scenario here is that the EZ Pull spring set up lightens

the force required to retract the bolt by being weaker springs. This increases

the recoil velocity of the bolt and increases the force with which it hits the

buffer/receiver at full recoil.

By now I would think many hundreds of these spring sets are in use and

I know of no ill effects, however I have never heard that any scientific and/or

engineering approach was put into the design of these springs such as prolonged

firing or other testing.

The semi-receivers do not appear to be high-strength steel, and there is some

evidence to suggest they are machined from leaded steel to make them faster

and easier to make by reducing machining time. This leaded steel is quite soft

and would fail sooner than better steels. A while back there was a cadre of Thompson

owners who unwisely increased the rate of fire of their West Hurley guns by eliminating

H locks and using "hi-speed" springs in a quest for M1921 cyclic rates. I believe some

of these guns ended up with cracked receivers at the tail.

Your aluminum receiver would have even less strength than leaded steel so I would

try not to overload it.

I have been meaning to send some WH and Kahr receivers to the lab to be tested

for lead, this is a good reminder...

 

Bob

Edited July 28, 2009 by reconbob

[nfafan]

Thanks for the reply!

 

Maybe the next time I have it apart I'll see about adding a thinnish peice of leather between the back of the recvr "wall" and the back plate of the spring guide. We'll see how that goes.

 

Right now the "hard poly" buffer that came with the springs is probably not absorbing as much of the recoil impulse as would the "dead-blow" material of leather.

 

In fact, I will try this on my M-10/45; maybe the absorbant effect of a thick leather buffer is a cheap-trick to slightly slowing that bullet-hose down. Although the real answer is dropping the lonnnnnnng green on the Lage upper with the longer, heavier bolt.

[Joe H]

Nafafan,

 

I'm not sure leather will solve your problem. It has no "spring back". You might want to try a lower durometer polyurethane for the additonal buffer. The hard poly is in the 90-100 (Shore A)Durometer range. I've had excellent results using 60 durometer poly for the added buffer in my Thompson semi. I used 100 poly as a replacement for the original fiber buffer from the parts kit and added a 3/16" 60 durometer poly as an additional buffer.

 

Joe

[Turpin81]

This is an old post. However I would like to know, If the Newer A.Ordnance 1927's steel are made of leaded steel or not?

[T Hound]

Leaded steel? I don't think so. I have never heard that it used leaded steel.

 

As for the issue with greater force generation: Recon Bob is correct. Because the

EZ springs are weaker relative to the original springs, which are stronger, then the

weakened springs allow the bolt to travel back further and at greater speed unlike

the original stronger springs which cause the bolt to disippate more of the recoil

force in the springs. The weaker springs allow LESS force to be disippated and

therefore MORE force hits the back end of the receiver. This could eventually

crack a weak receiver such as aluminum.

Edited January 14, 2013 by T Hound