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Posted: 12/24/2004 5:00:03 PM EDT
I have a Bushy Lower with a Stoner 25 Trigger-Hammer.
The firing pin retaining pin has been battered and deformed after a few hundred rounds routinly for about 2 years.
The top-front of the hammer has a worn area...which I suspect it where it is hitting the firing pin collar an focrcing it into the retaining pin.

Rather than shaving the top of an expensive SR25 hammer...what about sticking a firing pin in a drill chuck, and polishing down the collar till it no longer hits the top of the hammer?

Firing pins are cheaper to mess up than Stoner Trigger parts, aren't they?

Happy Holidays!
Link Posted: 12/24/2004 5:34:48 PM EDT
I wonder if you have an m16 firing pin in it , measure it.

The only difference between the firing pins is the diameter of the flange for the retaining pin. The M16 firing pin is .370" diameter and the AR15 flange is .340" diameter. While an AR15 firing pin will work fine in an M16, the M16 firing pin will have an interference with the AR15 hammer which could cause the bolt carrier to hang up on the firing pin when cycled.
Thank you.

Link Posted: 12/24/2004 6:01:51 PM EDT
[Last Edit: 12/24/2004 6:30:18 PM EDT by drshame]

.343 AR 15 Firing Pin

A second came in at .338
The 3Rd measured at .329

I substituted the smallest on the AR that was giving me retaining pin problems..I'll see if that fixes it.

Anyone else see a wide variation in firing pin collr dimensions...and what effedct does it have?

Link Posted: 12/24/2004 8:33:09 PM EDT
The Colt ones I have are .330 others called ar15 ones are usually closer to .340.
Link Posted: 12/24/2004 8:38:41 PM EDT
I have one rifle that was doing this.

The real culprit is the notched hammer. If you have a notched hammer, you can grind a bevel on the notch to allow it to slip past the fp collar.

Better is to change out the notched hammer for an unnotched one. DPMS has these unnotched hammers. I have these on all of my AR's now.

Or for a total cure, sub the RRA "enhanced" bolt carrier. This one totally shrouds the firing pin.
Link Posted: 12/25/2004 3:55:32 AM EDT
The un notched hammer sits higher and would hit also. Grind to much off the hammer and the carrier will not push it down far enough to catch the disconnector.
Link Posted: 12/25/2004 2:31:33 PM EDT
Problem is the safety feature of the non shrouded carrier. The hammer is going to ride the firing pin collar on the closing stroke no matter what. This is due to the carrier needing to lower the hammer to allow the trigger or disconnector sears to engage, yet still allow the hammer to catch the collar if the disconnector fails.

Now on the hammer, you need to round the top edge of the firing pin contact pad on the hammer to allow the firing pin collar to make contact with the hammer father down the contact pad surface, and not at the very top edge (current binding area). Go slowly removing material and test often since the contact pad is what is being contacted during hammer reset, and if you round the top edge too much, the carrier will not lower the hammer far enough to engage the trigger/disconnector sear.

Or, you could just replace the non-shrouded firing pin carrier to a RRA shrouded carrier and be done with it.
Link Posted: 12/25/2004 2:34:58 PM EDT

Originally Posted By A_Free_Man:

Or for a total cure, sub the RRA "enhanced" bolt carrier. This one totally shrouds the firing pin.

What he said.

Link Posted: 1/4/2005 10:43:15 AM EDT
Got a shrouded bolt carrier from John Holliger at WOA.

Will test fire at the range on my next opportunity, and I hope my problem will be solved.

New Bolt Carrier: $75.00

New Retaining Pin: $1.25

How many retaining pins could I buy for $75 if I never wanted to really fix the problem...or what's the value in spending $75 to save a $1.25 part?

Yeah, I really saved money because if I shoot the AR for another 30 years, the new bolt carrier will have more than paid for itself.

At least I've got a spare carrier in my parts kit now to go along with 2 dozen extra retaining pins.
Link Posted: 1/4/2005 2:16:18 PM EDT

Originally Posted By gregw45:

Originally Posted By A_Free_Man:

Or for a total cure, sub the RRA "enhanced" bolt carrier. This one totally shrouds the firing pin.

What he said.


Is that the only benefit to this "new" carrier. To protect the firing pin? or an I missing something else?
Link Posted: 1/4/2005 10:41:51 PM EDT
Link Posted: 1/5/2005 9:33:12 AM EDT
Link Posted: 1/5/2005 12:00:19 PM EDT
[Last Edit: 1/5/2005 12:10:48 PM EDT by Dano523]

Originally Posted By JohnM:
An issue with this topic never discussed, but equaly appropriate, and the right way to fix this problem would have been to ensure the disconnector retained the notched hammer below the striking dimension. One of the tasks the disconnector is required to preform during cycling of the action is proper hammer retention and it sounds like this retention dimension should have been examined before secondary fixes were implemented.

Just a thought.

JohnM at Home

In order for the disconnector to retain the hammer, the carrier must lower the hammer past the engagement point of the sears. Simple put, the hammer is going to make contact with the carrier/firing pin collar as the carrier passes over (Non shrouded bolt), even when the disconnector is positioned to retain the hammer (No third/lowest engagement point of the Auto sear on the hammer hook).

The problem is not the retention of the hammer on the disconnector, but the angle/contact point the firing pin collar is going to make with the hammer as it moves across towards Bolt lock-up.

Again, the solution when using a non-shrouded carrier is to relieve/lower the top edge of the firing pin contact pad (referenced angle of the hammer to the firing pin collar when items are not within the original SP-1 spec) to allow the beginning glide point of the firing pin collar to be within the contact area (smooth surface) of the firing pin pad, and not at the very beginning of the hammer pad end edge.

Trust me, no one is trying to re-invent the wheel. We are just trying to bring the rifle systems back into tune when one or more items are not within the original spec of the SP-1 (what most current semi systems are based upon).

Link Posted: 1/6/2005 12:35:18 PM EDT
Link Posted: 1/6/2005 2:54:22 PM EDT
I am also having retainer pin deformation, the rifle is a Bushy varminter that I installed a Jewell trigger set in. The retainer pin is being bent to the rear and there are marks on the very edge of the large flange of the firing pin on the rear side, I assume this is where it is hitting the retainer pin. I cannot find any marks on the foward face of the flangeDid you see marks on the foward side of the firing pin flange? I'd like to think there is another way to fix this rather than buying a new carrier, but if not, oh well it will be time to go shopping.
Link Posted: 1/7/2005 3:28:16 PM EDT
1: Find a firing pin with a smaller collar.

2: Carefully check out your hammer, looking for unusual wear-polishing near the front and top of hammer. If you have those signs, CAREFULLY stone them down so it doesn't drive the firing pin collar into the retaining pin.

3. Buy a new carrier with a fully covered firing pin.
Link Posted: 1/7/2005 4:17:26 PM EDT
4. Round the top edge of the hammer's firing pin contact pad.
Link Posted: 1/8/2005 3:14:35 AM EDT
I think I will just get the shrouded bolt carrier. I don't think Jewell would sell me just a hammer if I got carried away with a file and stone, and if they did it probably cost more than a new carrier.
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