Dropping USGI parts into a Springfield M1A?

[Morgan338LM]

Just wondering if anyone has experience doing this, if the bolt/oprod/gas system etc... can just be switched out or if it gets complicated and needs fitting. Thanks! [Beer]

[BPTactical]

Most parts aside from the bolt are a direct drop in. If you swap bolts headspace will be an issue. Might as well upgrade to National Match bits & pieces if feasible. If you are going with NM parts some work may be needed to get the real benefits from them.

[Troublco]

You may have issues with the fit of a different trigger group depending on wear and/or stock. One area where parts swapping can be a benefit is gas pistons. If you have a few to choose from, sometimes you can find one that will improve the gun's accuracy by shooting the gun with each piston and tracking your groups. I don't remember the whys of this, but I know it's been done.

On a related note, there are some Garand parts which will work in an M1A, such as the extractor, the rear sight parts, Hammer and associated parts, trigger and pin, sear and pin, and the rear sling swivel and screw. I may have missed a couple, but you get the idea.

[10x]

A bolt needs to have the headspace checked. Otherwise everything else will fit.
There might need to be some minor fitting with the stock around the trigger group. You want to leave that tight.

[flan7211]

Just wondering if anyone has experience doing this, if the bolt/oprod/gas system etc... can just be switched out or if it gets complicated and needs fitting. Thanks! [Beer]

Thanks for asking just asked that question myself today[HiFive]. Let me know how your guy takes it.

[NukeRJ]

I'm with BP on this one. If you are going to swap parts, go with nm new manufacture. I know you are trying to replace the MIM parts with the forged mil spec bits, but remember that all the military spec parts have a looser fit for reliability and interchangeability. Just so long as you have plenty of parts to swap and lots of time to test for accuracy changes, then go for it. If you don't care about accuracy then no worries.
I still have all original Springfield commercial parts. Nothing ever broken. And it's sub moa with a unitized gas block.

[BPTactical]

National Match components are for the most part USGI parts that are measured and selected to the minimum of the spec range. Theoretically the tighter fitting parts will result in better mechanical repeatability which is where the consistency of the group comes in. NM rear sights are adjustable in either 1/2 or 1/4 MOA, I don't recall right off the bat. NM front sights are narrower for better resolution of the target.
Although the majority are "drop ins" and you can load the rifle with NM components you really dont reap the full gains. They really need to fitted and "massaged" into one homogeneous unit which then becomes a precision rifle.
Things like aligning the Op rod correctly, unitizing the gas system, installing the gas system correctly etc are just as critical if not moreso than the parts you are using.

[NukeRJ]

interesting - I thought most NM parts had to generally be lightly fitted no matter what - because if it is a drop in part then it isn't truly a NM fit?

[BPTactical]

interesting - I thought most NM parts had to generally be lightly fitted no matter what - because if it is a drop in part then it isn't truly a NM fit?

Not necessarily so
Some "NM" parts like sights and recoil spring guides are generally a true drop in with no real fitting required.
But like I said if you want to reap the full benefit of NM parts then fitting and proper installation procedures must be adhered to.
Example-You can drop in a NM gas piston and unitized gas cylinder but if you dont properly fit the gas cylinder lock for 'time' then you wont get the full benefit.
You can glass bed it but if you dont know how to properly pre load the barrel and trigger guard lock up then it is a waste.
Screw a NM flash hider on without aligning and reaming and you can shave lead and kiss any form of accuracy bye bye.

[topshooter]

As a Retired US ARMORER - MATCH AND SNIPER Builder for the US NAVY - US ARMY and "with" the USMC... MATCH SHOOTER...State Champion.. Holy cow... I have done a bit..... I still build rifles... I do full parkerizing and fitting. I have all the proper GI GAGES for the M1 - and M14.
Since 1956.....geezz... Before that - was CIVIL WAR MUSKETS...which are my soft spot.......... Still have the one I bought in Bannermans Store at 501 Broadway.......man....was that a STORE !!!!!! If you need some miracle on a M1- M1A ...let me know... I perform them now and then....