BCG firing pin excessive movement?

[gregshin]

I bought a BCG and the firing pin moves back and forth at least ½ an inch. Is this normal for a BCG?

I own BCM, Spikes, and YHM BCGs and never seen this much movement before.

Should i return it or is it GTG?

[Onyx Z]

Completely normal.

[markm]

Half inch? Got a pic of the firing pin? There's roughly a half inch between the head and the spool on the firing pin.... so as long as it's the right pin and the cotter pin is holding it in place, you should be fine.

[Obscenejesster]

If it doesn't move back and forth, how do you expect it to strike the primer after the hammer strikes it?

[gregshin]

If it doesn't move back and forth, how do you expect it to strike the primer after the hammer strikes it?

i understand that the firing pin must move to ignite the primer.

i took my spike's bcg and that pin moves say 1/8 of an inch back and forth.

this new bcg's pin moves literally a 1/2 inch back and forth. never seen this before on 6 other BCGs i own.

[markm]

On second thought.... the critical item here would be the placement of the firing pin retaining pin. If, for some reason, the hole where you insert the retaining pin was positioned back from the bolt more than your other BCGs, you'd get excessive pin float.

Can you place this BCG by another one... maybe standing on end... and compare the position of the retaining pin hole??

[redmist]

On second thought.... the critical item here would be the placement of the firing pin retaining pin. If, for some reason, the hole where you insert the retaining pin was positioned back from the bolt more than your other BCGs, you'd get excessive pin float.

Can you place this BCG by another one... maybe standing on end... and compare the position of the retaining pin hole??

The critical part for me would be the bore that stops the firing pin from over travel. If it is to deep, it allows the firing pin to protrude with the bolt out of lock. This would also cause excessive pin float.

[markm]

That's true too. But I think the bolt tail will limit the forward movement too. Occam's razor would suggest that if there's a problem, the pin hole location would be the issue. ;)

[MarkG]

The critical part for me would be the bore that stops the firing pin from over travel. If it is to deep, it allows the firing pin to protrude with the bolt out of lock. This would also cause excessive pin float.

One small problem...

The "bore" of the carrier doesn't limit the forward travel of the firing pin, the tail of the bolt does.

[Eric D.]

Maybe I'm misunderstanding your meaning. The rear bore of the carrier does limit how far forward the pin can move. The firing pin can move forward until the large diameter of its tail bottoms out in the rear bore.


One small problem...

The "bore" of the carrier doesn't limit the forward travel of the firing pin, the tail of the bolt does.

At any rate, if the rear bore were too deep the hammer wouldn't stay in contact with the firing pin as it struck the primer and you'd basically be relying on firing pin momentum to ignite the primer. 1/2" seems excessive to me.

Another thought: If the rear bore was deep enough to allow firing protrusion with the bolt unlocked there would be a complete thru-hole down the carrier; the firing pin would be able to fall through of the front of the carrier with the bolt removed.

[MarkG]

The rear bore of the carrier does limit how far forward the pin can move. The firing pin can move forward until the large diameter of its tail bottoms out in the rear bore.

Remove the firing pin retainer and firing pin from a bolt group. Push the bolt reward into its locked position. I'm certain that if you look down through the back of the bolt carrier, you'll find that the tail of the bolt is the high point in the counter bore at the back. Are you still sure that the bolt carrier limits the forward movement of the firing pin?

[Eric D.]

I was reading your post as 'tail of the *firing pin*' instead of 'tail of the *bolt*'...Facepalm. It didn't make sense because I was thinking "How can the firing pin's own tail limit its travel?" You are correct.


Remove the firing pin retainer and firing pin from a bolt group. Push the bolt reward into its locked position. I'm certain that if you look down through the back of the bolt carrier, you'll find that the tail of the bolt is the high point in the counter bore at the back. Are you still sure that the bolt carrier limits the forward movement of the firing pin?

[MarkG]

I was reading your post as 'tail of the *firing pin*' instead of 'tail of the *bolt*'...Facepalm. It didn't make sense because I was thinking "How can the firing pin's own tail limit its travel?" You are correct.

All good...

Sent from my XT1056 using Tapatalk