7.62 M1 Garand sticky chamber

[boatbod]

I've yet to try a chamber cast. Is is likely to reveal more than what can be seen with a flashlight and fired brass?

[tdeon221]

You'd see exactly what's up. A hawkeye borescope would work too. At this point just put a new barrel on it. You're at the point of diminishing returns. You've got the tools. With what you've done already I would expect 2"-4" groups at 200 from position with good ammo with a barrel change. Good being Sierra matchkings with about 41.5gr of IMR 4064(308). If that load doesn't work in any m1 or m14 something's wrong with the gun.

[boatbod]

So it seems Krieger make the best barrel, but how do they compare to the significantly less costly Criterions? Will the average shooter even notice the difference considering we're talking about a rifle with iron sights?

[tdeon221]

Criterion are button rifled and are made by Kreiger. To capitalize on the max accuracy potential of a barrel all national match mods should be done. So it depends what you want to do with it. Full course with a garand you need a quality barrel and all the tricks and you'll still have a hard time keeping up with the AR's. A games gun still needs a quality barrel but you're limited to what you can do to the rifle, you're also only shooting to 200 yards on the SR Target which has a three minute ten ring. You can shoot very small groups with iron sights, they're not a limiting factor.

[boatbod]

Went to help a buddy sight in his new bolt gun today, so used the excuse to sling some more lead downrange.

20rds of commercial .308 Winchester 150gr (2850fps) cycled fine every time while 147gr 7.62x51 still did not. I only bring this up because it was readily apparent the empty .308 cases were being flung considerably more aggressively than their 7.62 cousins. Curiously, unfired .308 was also a sloppy fit in the chamber, whereas the 7.62 felt pretty snug and had minimal noticeable vertical/side-side free play. Fired brass of both types mic'd at 0.470" just in front of the base, while the unfired (again of both types) was around 0.003" smaller. SAMMI says 0.4709" for a .308 which is right where we are.

At this point I've basically decided to put a new barrel on and move forward. Looking at the rear of the chamber through a 10x loupe shows a pretty rough finish, even after multiple sessions with the 800 grit compound. With that and the need to make a proper breeching washer to achieve decent torque at the correct index, it's just going to be easier to start over.

Even with the problems, this is still a fun gun to shoot! I never figured I'd be reliably able to plink an 18" square steel plate at 300yds with iron sights. Mr Garand makes it almost too easy

Thank you to everyone who got me to this point. Hopefully my next update will be once I have it fully sorted (when funds permit).