How Much "Slop" In A M14/M1A Bolt?

[.455_Hunter]

Greetings!

Should a M14/M1a bolt have any "front to back" slop when the internal hammer is cocked and the bolt fully forward on an empty chamber?

Thanks!

Hunter

 

[Reloadron]

Greetings!

Should a M14/M1a bolt have any "front to back" slop when the internal hammer is cocked and the bolt fully forward on an empty chamber?

Thanks!

Hunter

Some back and forth travel is normal under the conditions you describe. How much? On my own match rifle I can work a .004" shim (feeler gauge) between the bolt lugs and the receiver recess (locking lug surfaces) equal on both lugs. I can't get a .005" shim in there.

So yes, some front to back play is normal.

Years ago I did lap the bolt lugs on this rifle.

Ron

 

[Slamfire]

A rifle that does not have some clearance between the barrel and bolt face is going to have troubles when unburnt powder falls between them. There has to be some gap or the rifle will malfunction.

There are a number of critical dimensions, headspace is one. Another is just how much cartridge is hanging out of the barrel. The cartridge case must be supported by the chamber or it will rupture. The case head is thick enough that it won't rupture under normal pressures, but case sidewalls thin out very quickly up from the case head. You can find google "Glock 40 S&W unsupported chambers" and find pictures of blown sidewalls of 40 caliber cases where the Glock chamber did not fully support the sidewalls of the case

http://thefiringline.com/forums/showthread.php?t=230344

http://www.xdtalk.com/forums/xd-45acp-discussion-room/87753-45-super-xd-3.html

http://thefiringline.com/forums/showthread.php?t=207548


http://skurj.blogspot.com/2012/09/the-glock-monniker-and-mythos.html

As for lapping bolts, I do not agree with that practice on M1a's if the lug engagement is around 75%. Removing case just reduces the life time of the bolt, the case is not all that deep and the rifle is not a bench rest rifle anyway. I think the proper way to lap the bolt is by shooting it several thousands of times with grease between the lug and receiver. That's what I did and it does lap in without an abrasive.