M1a/m14 guru's

[Jarhead715]

I have little experence in fixing firearms, so try to keep the flaming down. The rifle has maybe 300 rounds through it. Had a problem with the bolt and since replaced most of the springfield parts with new old stock USGI stuff.
Problem I'm having is the synthetic stock seems really loose and the grouping at 100 yards is scattered at 3 inchs apart off a bipod. Rifle has a Sadlak mount and a decent redfield scope. Is there anyway to tighten the stock to the barrel assembly to improve the groups? Shoots the same on iron sights off a sand bag. I have been told to shim the stock but have no idea how.
Dont think its my marksmanship has the same results with 2 other shooters. All former Marines. Any help would be appreciated.

[ar15barrels]

Get one of the old McMillan fiberglass stocks and bed the action into it.
Shim the gas cylinder as well.

[Jarhead715]

Shim the gas cylinder? As in the metel piece that kind of floats around the barrel to keep the front of the stock in place? That piece is really poorly made and is very loose fitting. Think is called the front band? Thanks

[6mmintl]

Two things that cause bigger groups in M1A's is the rotation movement of the op rod guide and gas cylinder/ferrel assembly allowing the barrel to NOT return to the same position/location from shot to shot.


You need to unitize the front ferrel to the gas cylinder typically starting with opening the barrel hole of the ferrel to be clear of touching the barrel, then with a alignment fixture thru ferrel centered on gas cylinder, careful welding on two sides to stop rotational movement of ferrel. Careful welding so that you do not distort the gas cylinder and bind up gas plug which should also be polished .001" under size. Springfield NM guns used to have two screws fromt back side screwed thru ferrel into gas cylinder, they always came loose, a lot of competitors would weld screw heads to ferrel to stop movement but they eventually would break again.


Then you shim to orient the gas cylinder lockup tight, then never remove gas cylinder lock or gas cylinder.

The next thing is to pull off op rod guide degrease, stipple the machined seat on barrel, align the op rod guide with action ears (bottom) and red locktite it back in place, and replace the roll pin with a new one.

From here you move on to the rear sight, stoning sight base recess, sight base and tightening sight stem/slide in sight base.

[Jarhead715]

Ok then, way above my skills. Thanks for the info back to a gunsmith.

[fuubar67]

Just start with the basics:

cleanup the gas system:

http://www.sadlak.com/si_tools.html

Clean up the bore and the chamber:

http://www.brownells.com/gun-cleaning-chemicals/brushes-amp-bore-snakes/chamber-brushes/m14-m1a-m1-ratchet-chamber-brush-prod1242.aspx

Check the oprod, guide and the spring.

If you can dismount the muzzle brake check for fouling or scoring at the end of the barrel.

Clean the bolt, lube the roller.

More severe problems I go to US firearms CO in Sunnyvale with my M1A.

[Jarhead715]

Thanks for all the info guys. Decided to send it to Arrington Accuracy Works
Going to have all the goodies installed. I have learned over the years better to pay someone who knows what he is doing, than making bigger problems trying to do it myself. I should have just spent up front and bought the super match.

[Mayor McRifle]

Thanks for all the info guys. Decided to send it to Arrington Accuracy Works
Going to have all the goodies installed. I have learned over the years better to pay someone who knows what he is doing, than making bigger problems trying to do it myself. I should have just spent up front and bought the super match.

You can do a lot of the match conditioning yourself: http://www.amazon.com/owners-guide-m...&keywords=m-14

[ar15barrels]

Two things that cause bigger groups in M1A's is the rotation movement of the op rod guide and gas cylinder/ferrel assembly allowing the barrel to NOT return to the same position/location from shot to shot.

The next thing is to pull off op rod guide degrease, stipple the machined seat on barrel, align the op rod guide with action ears (bottom) and red locktite it back in place, and replace the roll pin with a new one.

I put a heavy Kreiger barrel on an M1a today.
It came with an oversized op rod guide that I had to heat up to even get it to fit on the barrel.
I setup the barrelled action sideways in the milling machine and got the oprod guide centered under the barrel within a couple thousandths of an inch and then cross pinned it to the barrel with the two 1/8" roll pins that krieger includes.