AR junked firing pin retainer twice. What's the problem?

The very first batch of CQA's came with FA BCG's

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since then they've become more commercial - also the first ones had a serial number (different from the rifle's SN) electro pencilled very neatly under the forward assist. It seemed to suggest the lowers and uppers were coming from different factories - the rest of the SN's were a mess.
 
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Silver,

Based on what I see, there should be no interaction between the firing pin and the hammer because the bottom of the bolt is completely enclosed.

So.

What does that leave....

Thinking.

Hrm.

Ok, do you have a set of calipers?

With the bolt in the "closed" position (pushed to the rear) I'd like you to measure from the bolt-face to the front of the firing pin retaining pin hole.

The *idea* I'm pursuing here is that your firing pin retaining pin hole may be drilled/located slightly forward or rear of where it should be, so that when the hammer strikes the firing pin, the firing pin is impacting the retaining pin? Does that make sense?

I'm grasping at straws here, because your bolt type is eliminating the hammer drag/firing pin interface issue.

NS
 
Thanks for sticking with me. I don't have a set of calipers but I can get one maybe tonight. If it turns out that it is out of spec then I guess I just retire the whole BCG or leave it for plinking?

A retaining pin should just normally never come loose then?
 
At the very least you should have a bunch of spare parts after, like a bolt, firing pin, cam pin, extractor. It sucks to have to replace the BCG (If you have to). but at least you will have something to show for it. I never had the cotter pin fall out in the army, every one that I ever worked with had to be pulled out with a needlenose or whatever else was handy.
 
hmmm I never had mine fall out, but it is very easy to pull it out without tools, maybe I should bend mine a bit

xenasdad said:
At the very least you should have a bunch of spare parts after, like a bolt, firing pin, cam pin, extractor. It sucks to have to replace the BCG (If you have to). but at least you will have something to show for it. I never had the cotter pin fall out in the army, every one that I ever worked with had to be pulled out with a needlenose or whatever else was handy.
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luke s said:
hmmm I never had mine fall out, but it is very easy to pull it out without tools, maybe I should bend mine a bit
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I would leave it alone. The reason I could never get ahold of it is because I have big fat fingers. It wasn't that they were super tight I just couldn't get hold of the loop end.
 
Yea I have small piano playing fingers so I can pinch mine out, but much easier with tip of a tool or knife tip. I was thinking maybe the hole for it is too large. You are absolutely right I should have replacement parts handy. I'll go order them now.

I'm still wondering about the BCG though. Nothing wrong with my firing pin, right? The one with the wider diameter?
 
Silveragent said:
Yea I have small piano playing fingers so I can pinch mine out, but much easier with tip of a tool or knife tip. I was thinking maybe the hole for it is too large. You are absolutely right I should have replacement parts handy. I'll go order them now.

I'm still wondering about the BCG though. Nothing wrong with my firing pin, right? The one with the wider diameter?
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No I didn't mean you needed to buy parts I meant that if the BCG is not fixable you can strip it for parts. sorry my bad.
 
Probably, I will just keep it and use it for plinking and get a new BCG with new parts if I need it for anything serious IF it turns out it is the BCG.

I have a whole other gun I just built that I can transition to for serious stuff.
 
OP - can you explain how the pin is breaking, or where you're finding the pieces? Is the firing pin impacting it and it's shearing?

Edit - from which side of the bolt do you install your cotter pin? Ejection port side or the left side?

Edit - you found the cotter pin inside the barrel??
 
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Each time the pin was actually jammed in the barrel with the bcg jammed forward into the barrel on top of it. At first I and another person pulling at it couldn't free the bcg and the cause was that the cotter pin was actually in the barrel, not in its hole, actually free of the bcg. The pin in each case wasn't ever broken, just bent (first time nearly straight, second time the replacement cotter pin was just bent a bit).

As to which side, I don't remember off hand. I think if I do it one way, the pin protrudes from the hole and outside the bcg; so I put it in the other side where it is in the hole and does not protrude.

*MALICE* said:
OP - can you explain how the pin is breaking, or where you're finding the pieces? Is the firing pin impacting it and it's shearing?

Edit - from which side of the bolt do you install your cotter pin? Ejection port side or the left side?

Edit - you found the cotter pin inside the barrel??
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I'm thinking that you are installing them from the ejection port side. I have a hunch that if you install the pin from the left side this problem will mysteriously disappear.
 
*MALICE* said:
I'm thinking that you are installing them from the ejection port side. I have a hunch that if you install the pin from the left side this problem will mysteriously disappear.
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This is exactly what I was thinking...
I was going to bring it up early on but thought to myself "can't be. It obviously goes in one way and not the other" but it sure sounds like the case.
 
Oh....

FINE....you guys go proposing the EASY solution that us gun weenies didn't think of because it was in front of our faces.

FINE. NO MORE LESSONS FOR YOU.

(Actually, I think they're right...)
 
Hold on a sec here… in this pic the pin is on the wrong side is it not, but the bolt carrier appears to be designed that way… normally the cotter pin would be captured by the receiver no, but in this pic you could pull that pin out through the ejection port… if it came out, I would assume it would end up on the ground, or in front of the bolt I guess… what gives?

enefgee said:
DSC00796.jpg
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Hmm but the cause is the pin somehow coming loose, right? So if it came loose, it either goes flying and I never find it or it ends up in the receiver. Either way, it is coming loose right?

EDIT: heading home, so I will see which way I've been putting the pin.
 
Silveragent said:
Hmm but the cause is the pin somehow coming loose, right? So if it came loose, it either goes flying and I never find it or it ends up in the receiver. Either way, it is coming loose right?

EDIT: heading home, so I will see which way I've been putting the pin.
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I guess the best way to answer that is to see which way your carrier is… normally the pin is captured by the receiver and can't come out... from the pics you posted I would venture to guess it is like enefgee’s… if so I am not sure what to do, does the pin fit booth ways? If not, I guess you could try to widen the legs on the cotter pin… the obvious thing is to get a new carrier, which is easier said than done right now…
 
NavyShooter said:
Oh....

FINE....you guys go proposing the EASY solution that us gun weenies didn't think of because it was in front of our faces.

FINE. NO MORE LESSONS FOR YOU.

(Actually, I think they're right...)
Click to expand...

LOL! No offense to Malice, because his question/hunch is clever, but I hope that, after all your very informative posts, his hunch turns out to be incorrect ;)
 
So I'm home and I tried putting the pin in both ways. On the ejection side, it protrudes from the hole, so I'm pretty sure I put it in the other way. Which side should it go?

First pic: protruding from ejection side.
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Second pic: it goes in flush inside the hole.
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If not, I guess you could try to widen the legs on the cotter pin… the obvious thing is to get a new carrier, which is easier said than done right now…
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Well yeah. If I can't find a basic field repair kit I'm not going to pay $300 for a BCG.
 
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