Broken Buffer retaining pin

[Iraqgunz]

Get rid of the Accu-crap. The lower receiver extension should be screwed in until the lip of the extension contacts the lip of the retaining pin. It will ideally be about 1/3 of the way. The retainer should move up/down freely. You also need to ensure that the castle nut and endplate are torqued correctly and then staked.

Great advice. You guys are better than a You Tube video!

I will need a new buffer retainer pin to trouble shoot.

This is a high quality billet lower by Bomberg but I think the stock extension tube may have been screwed too far forward. Whats left of the buffer pin still moved up and down but the edge of the tube looks like it is awfully close to the pin stud. I checked two other rifles and the rear of BCG does touch the buffer face when you swing it down to close. So I know what to look for now, and did not before.

Leaveammo to me. The rifle did not go into battery without the retainer pin holding the buffer face in position. thats why I knew something was wrong? Guess I can try it without the retainer pin once I back off the end plate and extension nut.

I am using a Colt upper, and there is some side to side play in the upper so I installed an accu wedge that tightened it up.

[556x45]

Iraqgunz,

I took my rifle to my NFA dealer and friend, tom Denall, TDF manufacturing. the tip of the retainer plunger was underneath the trigger assembly. Based on color (light gray) of the broken plunger he thought it had not been heat treated properly. He replaced it with a new one, spring was OK. When lowering the upper onto the lower, the rear of the bolt carrier did not contact the buffer until it was almost closed. compared to my other two rifles which contact 1/2 way down, it is not alot of pressure on the face of the buffer. It is a Colt upper. the castle nut was not torqued tight enough either. Back to the range. I will try without accuwedge but its a 3/4 - 1 inch ES rifle the way it is.

[markm]

When lowering the upper onto the lower, the rear of the bolt carrier did not contact the buffer until it was almost closed. compared to my other two rifles which contact 1/2 way down, it is not alot of pressure on the face of the buffer.

The buffer retaining pin hole is improperly located. There's nothing that can be done to fix this. You'll likely continue to damage your buffer face and beat up the retainers.

(no change of upper brand/make will make a difference on this.)

[Blak1508]

I had a retainer plunger sheer off, it was from a CMMG kit I had obtained during the panic figuring I would switch out later. The sheer area was suspect and I wondered if the part was even spec or treated properly also. I replaced with a part from a DD LPK and no issues since that was 3000 miles ago, I did not have any out of ordinary marks on my buffer or BCG, the lower is BCM and all parts torqued to spec, I triple checked that.

I either agree with Markm, or plunger failure, in addition IG advice to ensure those parts do not move and at that point working free and causing additional unwarranted stress on the retainer plunger.