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Instead of endlessly replacing firing pins ....


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Can we not redesign its dimensions to make it last? 
1. beef up the tip a bit, correspondingly enlarging the pin hole in the bolt face. 

2. Beef up the mid body diameter by just a hair. The bolt can shed some slivers of materials to give clearance to a slightly beefier firing pin. Compared to an AR15 fp’s, pccs’ looks quite fragile.  
Just thinking aloud. 
In our matches, a spare firing pin in the tool box wont save us a cof run w/ broken firing pin after the beep. 

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What are the dynamics of a straight blowback design that cause FP failure?  Are FP failures just as common in "stock" blowback designs versus changes (carrier weight, spring configuration,...) that might be used in a competition gun?

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Yeah, I don't get it with all the broken firing pins. I'm still on the original in my JP now for almost two years and I never broke one in the Colt I had the previous 2.5 years before that. And I had a replacement Timmney trigger in the Colt.

My guess is it has to do with all the jacking around with bolt and buffer weights.

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Well I just broke one that claimed to be unbreakable, in under 3k rounds. My bolt and buffer springs are same brand w/ the whole upper. No mods what so ever. 
I dont believe its something to do w/ blow back action or ammo loads, but think its the structural integrity of the part itself. Could be the design, materials used or both. 

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I think the problem with the 9mm FP compared to the regular M16 FP is what stops the forward momentum.

on the M16/AR15 I believe it’s stopped by the flange on the back of the FP impacting the back of the bolt

on the 9 mils it might be stopped by the shoulder at the tip or by the primer itself, which could cause it to flex every time it’s fired. I broke the tip off one of mine, and I’ve seen other break at the shoulder half way up.

but then again, I could be full of s#!t

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Im gonna fabricate a taccom AR9pcc firing pin due to mine broke its tip. Its not being sold in my country so its my only recourse. I lost the tip part so I need measurement of the pin entire length. Can somebody measure it for me? I emailed Tim but no reply, seemed he is not ok with my idea. I dont know of any patent issue if any.
Thank you 

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2 hours ago, BoyGlock said:

Im gonna fabricate a taccom AR9pcc firing pin due to mine broke its tip. Its not being sold in my country so its my only recourse. I lost the tip part so I need measurement of the pin entire length. Can somebody measure it for me? I emailed Tim but no reply, seemed he is not ok with my idea. I dont know of any patent issue if any.
Thank you 

Do you have access to a standard AR (223) firing pin? If so the tip is the same. It may also be possible to make one from it.

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I would think that the combination of bolt velocity and just the impact of the entire bolt being pushed back with a relatively floating pin puts the pin design under more stress than being in place and then pulled back like with an AR's gas impingement.  And then maybe the small rotation of an AR's bolt may also contribute to easing things, I dunno.  I've not broken one on my blowback AR9's but keep a spare in my bag, and I have seen it happen on someone's tuned PCC.  Maybe more robust materials like tool steel or titanium?

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18 hours ago, AHI said:

Do you have access to a standard AR (223) firing pin? If so the tip is the same. It may also be possible to make one from it.

Yes. Similar but shorter tip than AR9, and you are right it can be made into AR9 f. pin. 
 

 

 

Got the length at about 2-21/32”

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15 hours ago, MoRivera said:

I would think that the combination of bolt velocity and just the impact of the entire bolt being pushed back with a relatively floating pin puts the pin design under more stress than being in place and then pulled back like with an AR's gas impingement.  And then maybe the small rotation of an AR's bolt may also contribute to easing things, I dunno.  I've not broken one on my blowback AR9's but keep a spare in my bag, and I have seen it happen on someone's tuned PCC.  Maybe more robust materials like tool steel or titanium?

Still its 9 minor so it should not be much to handle

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15 hours ago, MoRivera said:

Maybe more robust materials like tool steel or titanium?

Most of the oem and after markets are tool steel and taccom’s is said to be of higher grade stainless steel tougher than tool steel. But they break unusually easy. So next thing to look see is the design of the pin, and maybe the bolt itself?

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On 11/18/2020 at 1:55 AM, BoyGlock said:

Still its 9 minor so it should not be much to handle

Agreed, but again we're talking a system that was designed to have the rear of the bolt be pushed against while stationary (well, it rotates at first) by gasses, and then pulled away by the reciprocating carrier.  In comparison in an AR9 with no separate bolt, there's no delay after striking and it's being moved back at a generally higher velocity.  So in that respect it's under a higher degree of impact.

 

The reason why I look at it this way is that those of us with the CMMG Radial Delayed Blowback have noticed very premature extractor spring wear as they come stock and have had to replace with an extra-power spring.  And that system is even more similar to an AR15's gas impingement except that it too is being forced back by recoil of the round, and from conversations and analyses it seems that has something to do with the forces that the spring is under as opposed to the original gas-piston/impingement action.

 

So perhaps the answer might somehow lie in making a smaller firing pin?  Like one used in a pistol that doesn't have as much mass behind it when slamming forward and then immediately back, maybe use a transfer bar that somehow won't stay on the pin when the bolt recoils?  That way less inertia stressing out that little tip area, I guess.  Whatever the options may be, I think it's the lack of delay in the blowback that's the key hurdle.

Edited by MoRivera
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13 hours ago, MoRivera said:

Agreed, but again we're talking a system that was designed to have the rear of the bolt be pushed against while stationary (well, it rotates at first) by gasses, and then pulled away by the reciprocating carrier.  In comparison in an AR9 with no separate bolt, there's no delay after striking and it's being moved back at a generally higher velocity.  So I that respect it's under a higher degree of impact.

 

The reason why I look at it this way is that those of us with the CMMG Radial Delayed Blowback have noticed very premature extractor spring wear as they come stock and have had to replace with an extra-power spring.  And that system is even more similar to an AR15's gas impingement except that it too is being forced back by recoil of the round, and from conversations and analyses it seems that has something to do with the forces that the spring is under as opposed to the original gas-piston/impingement action.

 

So perhaps the answer might somehow lie in making a smaller firing pin?  Like one used in a pistol that doesn't have as much mass behind it when slamming forward and then immediately back, maybe use a transfer bar that somehow won't stay on the pin when the bolt recoils?  That way less inertia stressing out that little tip area, I guess.  Whatever the options may be, I think its the lack of delay in the blowback that's the key hurdle.

Quite logical. So it needs a make over in design in the pin and bolt area. Lighter moving part makes for less inertia to hammer itself to breakage. 

Edited by BoyGlock
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after an original 400 round failure with an OEM pin, I rounded the strike end of a Colt pin and have about 7000 on it (multiple guns, now a RDB)... my perception to the peening of the OEM pin's edge was that the hammer did not strike it near the center line, and the rounded pin helped alleviate that problem

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19 hours ago, BoyGlock said:

Quite logical. So it needs a make over in design in the pin and bolt area. Lighter moving part makes for less inertia to hammer itself to breakage. 

I'm trying to look up straight-blowback examples, so far the Grease Gun and Thompson, and how those designs avoided firing-pin breakage.  From what I can tell they don't have as massive a hammer striking them from behind like an AR, and maybe they also rely on the forward momentum of the entire bolt more seeing as they both fire from an open bolt.  Maybe a redesign of the pin profile like Les mentions above might be all that's needed.

 

Also, don't know how related this would be, but when the Sig P365 first came out it was breaking the tip off the striker for some, and they later redesigned it to resist it better.  In the case of the Sig, it seemed that the cartridges were being 'sideswiped' a little by the firing pin as they ejected, as evidenced by some smeared indentations on ejected case primers, which may have applied some lateral force to the striker pin upon firing/cycling and contributed to them being snapped off.  I don't remember looking at any ejected case primers for my blowback AR9's, so I can't compare.  Here is a comparison of the old vs. newer striker tips...

 

7FPtGc.jpg.1549ca32f86857c05c5f4b98291ba223.jpg

 

Additionally, it would seem that the longer pin section could maybe avoid the base from making contact with the breech?  Anyway, just some more thoughts.

Edited by MoRivera
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I ordered a couple titanium pins from Iron City since they were having a sale.  We'll see how they hold up.  Probably really well for at least the foreseeable future since I'm not shooting as much while trying to conserve ammo these days. 😪

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On 11/26/2020 at 7:39 AM, BoyGlock said:

I wont feel it I guess, such a very small part that weight difference by feel of the whole gun would be next to none. 

Yeah, I'm not talking about the weight of the whole gun as that would be ridiculous-I'm talking about the weight of the firing pin which is the subject of this post.

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  • 2 weeks later...

 

On 11/27/2020 at 12:26 PM, MoRivera said:

I ordered a couple titanium pins from Iron City since they were having a sale.  We'll see how they hold up.  Probably really well for at least the foreseeable future since I'm not shooting as much while trying to conserve ammo these days. 😪

Only a data point of one, but I've been using an Iron City Rifleworks titanium pin in my PCC, with a Rise Armament Rave140 trigger. Currently 5700 rounds without firing pin failure, and I cannot see any cracks under a microscope yet.

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On 12/11/2020 at 10:39 PM, Arakisk said:

 

Only a data point of one, but I've been using an Iron City Rifleworks titanium pin in my PCC, with a Rise Armament Rave140 trigger. Currently 5700 rounds without firing pin failure, and I cannot see any cracks under a microscope yet.

I have the exact same combination in one gun.  Good to hear.

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