shoulder cut on buffer to remove strain on buffer retainer pin

[Les Snyder]

thought I'd pass this on... a friend's 9mm carbine showed wear around the edge of the buffer where the retaining pin was hitting... we stuck it in the lathe, and rebated the shoulder... the width equal to the height of the retaining pin, and depth enough so that it contacted the bolt and was pushed into the buffer tube enough to not make contact with the pin when the action was closed

[Patrick Scott]

Thats strange, an AR buffer should not contact the retainer pin when the gun is assembled when using "in spec" buffers and bolts.  

[Les Snyder]

Patrick... his is a pretty high end build... JP bolt and Vltor upper...lower was the early Colt dedicated forging , sorry don't remember the name... JP H2 buffer... my NFA bolt is slightly convex so pushes the buffer into the tube

[dcloudy777]

It it really continues to be a problem, ARs will run just fine with the retainer and spring removed altogether.

Just remember before you pop the pin and separate the receiver halves. 

[MickB]

Either the hole for the buffer retaining pin is out of spec or the JP bolt is too short. If a different bolt pushed the buffer back far enough, then the culprit is the JP bolt...

 

Mick

[Les Snyder]

so far, it has been a pretty simple solution to the problem

[Patrick Scott]

On 11/3/2016 at 5:43 PM, MickB said:

Either the hole for the buffer retaining pin is out of spec or the JP bolt is too short. If a different bolt pushed the buffer back far enough, then the culprit is the JP bolt...

 

Mick

Maybe, but I and others run a JP bolts with no issue.
Im wondering if that build just got bit by the tolerance stacking bug. The lower, upper, bolt, and barrel can all have an effect on the situation. It wouldnt be the first AR build I have seen with the same issue.