[ARCHIVED THREAD] - Excessive Shearing of Firing Pin Retaining Pin

Posted: 1/15/2006 9:53:10 PM EDT

I have a 16" CAR 6-position rifle. All parts RRA, except for Mega lower.

The gun is approximately 15 months old. I have fired around 1500 rounds through the gun. In that time, I have sheared 2 of these retaining pins. The first one, I sheared the retaining pin clean in half. The scond one, only 1 "prong" was sheared, the other appears fine.

Anybody know what would cause this? I clean the gun regularly. I shoot pretty quickly sometimes, sometimes unload 10 rounds rapidly, but nothing more than that.

Also, I need to know a good source for replacement retaining pins.

Posted: 1/16/2006 1:23:15 AM EDT

[#1]

AR-15 bolt carrier group or an RRA Enhanced? If it's an AR-15, that hammer is pounding against the firing pin which is pounding against the pin. Enough of the force against the pin and you have a breakage. If this is happening with an enhanced BC or an M16 carrier, try the KNC Perma-Pin. It's basically a solid pin rather than the bent wire one that comes standard with your bolt carrier. I think Global Tactical was selling them for around $10 a little while ago and it should be a solution to your problem.

Posted: 1/16/2006 2:19:34 PM EDT

[#2]

Is there any galling on the firing pin? Possible due to misalligned pin hole in bolt. Going to a perma pin is considerably stronger, but does not address the cause of the problem. I would replace bolt assembly with a new one and save old as a spare, or send back to RRA. (my 2 cents)

Posted: 1/16/2006 4:01:58 PM EDT

[#3]

From the FAQs:

Damage to firing pin retaining pin
or
Bolt carrier "catching" or "hanging up"

When used with slotted bolt carriers, hooked hammers can catch the underside of the firing pin, especially if the firing pin has a larger spool on it like those intended for the M16. The hammer will force the pin rearward against the firing pin retaining pin during the battery stroke. With repetition, this will bend the firing pin retaining pin. Sometimes the firing pin retaining pin is a simple, non-hardened, cotter pin. Some of these bend rather quickly. If you hold the trigger to the rear while working the bolt back and forth with the charging handle and the catch disappears you probably have an issue between the hammer and the firing pin. The best fix is to use a shrouded bolt carrier. You can also round the hook on the hammer to prevent it from snagging on the firing pin spool. A short trigger can also cause this by allowing the hammer to sit up too high when cocked.

Posted: 1/17/2006 11:38:03 PM EDT

[#4]

A tall hammer will cause this kind of damage.
Here is the "Tweak" (so to speak in Tweak's absence):
Clearance the end of the hammer.

Here is the view showing the hammer modification:

Here is the measurement you should stay BELOW to eliminate problems:

Posted: 1/19/2006 6:01:26 PM EDT

[#5]

You can try the fix that Randall has posted or just replace the hammer and spring... Either one should correct the problem...

[ARCHIVED THREAD] - Excessive Shearing of Firing Pin Retaining Pin

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[ARCHIVED THREAD] - Excessive Shearing of Firing Pin Retaining Pin

[ARCHIVED THREAD] - Excessive Shearing of Firing Pin Retaining Pin