My Barrel Suddenly Unthreaded

[jmoore]

This feels more like an M1/M14 subject, but to finish off this minor possible diversion here's some more photos:




A GI barrel that was removed from a new Springfield in order to install a match barrel. Note the "Geneseo, Ill. .308" mark:


This is a perfectly good standard weight "NM" barrel that still shoots 3" groups at 200 yards! It's off as I wanted to play with a shorter barrel and didn't want to cut this one. The peening was there from the factory.

There's good reason why this operation is so common. The shoulder is narrow, and breeching up will distort the contact face a fairly large amount. Here's a 3 month old 18 1/2" barrel that ws removed last week as it just wouldn't group well for completely unknown reasons. Note the distortion:



When Springfield Inc. went to reuse GI barrels that were previously installed they found MANY that would overturn. The peening worked well to utilize stock on hand. Later, Springfield made their action bodies a bit longer up front, but that led to new dramas with New Old Stock GI barrels and newly produced items, so that wasn't a good solution either. Problem is, you now have to be a guru/anorack to figure out the civilian action changes.

In closing, I think one reason that the peening business wasn't especially a big deal is that M1 match shooters have been peening barrel splines for decades in order to remove front sight wiggle. It works well, so why not do the barrel shoulder as required, too? As long as it doesn't hurt scores, no worries!

[purple]

I have a copy of the Cdn Army EME Instruction which deals with the use of breeching washers on the No4. It identifies and provides stock numbers for 3 different washers, 1"ID and11/4"OD in thicknesses of .002, .003, and .004. It stipulates that only 1 washer will be used, and never thicker than .004.