M1A Unitized Gas System...Screwed AND Welded?

[76Too]

So my most recent venture has been in the M1A category. When I bought my pre-ban a few months back, it came with a tackle box of USGI parts...what else was I going to do but plan another rifle build! Fast forward, i'm trying to decide which parts to use for my scout squad and I see that I actually have two unitized gas systems. One is welded (USMC Mod) and the other is screwed and welded...but from what I've come to understand, the options to unitize the gas system are welded or 'screwed and glued.' I'm not sure if this is some type of hybrid setup, but I'm trying to figure out which one will be the best for a CQB Scout Squad, and which will be better for the 'match' rifle i'm planning on building next.



Any ideas?

 

[johnN]

that is odd, was probably screwed together and then welded later on

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in that box of parts do you happen to have a extra gi bolt assy?

 

[PatMcD]

How do the welds look? TIG welding is the proper way to do those. A MIG or stick (!!) can put too much heat on the cylinder and distort it.
The screwed and welded one sounds like a belt and suspenders guy made it.

 

[mac1911]

I bowed out of the interest of the M1a while back but in my efforts to collect parts to build out a rifle IIRC
Fulton or one of the M1a folks put out a kit that came with the band and included drills taps and dies and the band was pre drilled...much like the NM lower band on the M1 garands.
Aslo My friends SAI super match has a welded unit. If you ask me it looks more like brazing than welding.

for me I really dont know how much accuracy you will gain vs welded or not welded.... screwed vs welded.
I only have scanned over the 2 books i have on accurizing the M1a. Although my thoughts are there are other items that would or will need attention first before this mod will help...
Again I would probably just leave the scout alone...do you plan on running match ammo in your scout?

You might want to call the seller and ask why those are in the box and not on the rifle....then examine the rifle you got (this is the on
e built by ? i forget) see whats on there for a gas cylinder?

as i sit here at work thinking about your problem....this is the gun built by Isaac McCaskill correct? looking at those parts its probably the attempt of the previous owners mods before consulting with Isaac ? Also it would not surprise me one bit in the early days of SAI to use the screw method.
I have another range friend who has his dads Full blown National Match rifle from the 80s and i will see if he knows if the gas cylinder is unitized?

as i mentioned i have only skimmed through the M1a section of the book but the M1 section had lots of good info and helped me squeeze out some accuracy or should I say consistency out of my M1 garands

The U.S. .30 Caliber Gas Operated Service Rifles: A Shop Manual, Volumes I & II

 

[76Too]

that is odd, was probably screwed together and then welded later on

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in that box of parts do you happen to have a extra gi bolt assy?

I have plans for basically everything in the box...I paid full price for the rifle, but made out like a bandit on the parts!

 

[Sweeney]

Those welds look pretty ugly on the backside. If you mount this gas cylinder, first grind the weld material flat on back, especially on the bottom weld and make sure it doesn't contact the ferrule on the end of the stock. Only the lip of the front band should contact the ferrule.

I weld mine and use a piece of drill rod as a heat sink in the cylinder. This is how the original XM25s were done. I also do the XM25 mod of drilling a 1/16" hole into the trepanning groove near the back end of the cylinder.

I believe the welding method was a Marine procedure while the screw and glue was the Army method. The effect is the same though the screw and glue disables the gas valve.