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Posted: 10/14/2013 8:16:10 PM EDT
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Took my rifle apart to clean, noticed this, is it normal wear and tear. I have a good bit of rounds through the rifle, but not over 5k.
Bolt is BCM, as is the FP 
Didnt get a definitive answer in my last thread. (GD  )
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Firing pin is supposed to stop on the bolt tail,not against the carrier.
Do a test...with BCG in hand pull bolt foward to unlocked position.Using a finger press the firing pin foward and hold it against the carrier.Now press the bolt reward to in battery position.As the bolt is pushed back into the carrier you will feel it push the firing pin back. If it does not test correctly may be an issue with the carrier or the bolt.If the bolt tail is short you should also check firing pin protrusion.. Only other way I could see the firing pin spool being peened that way is if you are firing the rifle without the BCG being in full battery. Have you been riding the charging handle and dry firing alot? |
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Firing pin is supposed to stop on the bolt tail,not against the carrier. Do a test...with BCG in hand pull bolt foward to unlocked position.Using a finger press the firing pin foward and hold it against the carrier.Now press the bolt reward to in battery position.As the bolt is pushed back into the carrier you will feel it push the firing pin back. If it does not test correctly may be an issue with the carrier or the bolt.If the bolt tail is short you should also check firing pin protrusion.. Only other way I could see the firing pin spool being peened that way is if you are firing the rifle without the BCG being in full battery. Have you been riding the charging handle and dry firing alot? I did the test you described, pushing the bolt back does move the firing pin back. I do dry fire a bit, but not excessively. I bring the charge handle back enough to reset the hammer, then fire a bit, as to feel trigger reset. could this cause it? |
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I did the test you described, pushing the bolt back does move the firing pin back. I do dry fire a bit, but not excessively. I bring the charge handle back enough to reset the hammer, then fire a bit, as to feel trigger reset. could this cause it? Quoted:
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Firing pin is supposed to stop on the bolt tail,not against the carrier. Do a test...with BCG in hand pull bolt foward to unlocked position.Using a finger press the firing pin foward and hold it against the carrier.Now press the bolt reward to in battery position.As the bolt is pushed back into the carrier you will feel it push the firing pin back. If it does not test correctly may be an issue with the carrier or the bolt.If the bolt tail is short you should also check firing pin protrusion.. Only other way I could see the firing pin spool being peened that way is if you are firing the rifle without the BCG being in full battery. Have you been riding the charging handle and dry firing alot? I did the test you described, pushing the bolt back does move the firing pin back. I do dry fire a bit, but not excessively. I bring the charge handle back enough to reset the hammer, then fire a bit, as to feel trigger reset. could this cause it? Yes I suppose it could...never seen it personally. When dry firing pull the charging handle back fully and let it go.If you don't like the clank of the BCG going into battery,then do as you say you have been and give the foward assist a couple love taps.You just want to make sure your BCG is fully in battery. Alternately you could also use snap caps/dummy rounds and use the action as its supposed to be,i.e. letting the BCG fly home from full stroke. Also if this is obviously the cause,your firing pin is likely fine if its not excessive.If the peening on the spool bothers you,dress the peened ridge down with sandpaper or a file.Personally I wouldn't worry about it.Good to have spares though. ETA By the way,just as a FYI,the firing pin spool hitting the carrier with the BCG not fully in battery is how the system prevents out of battery ignition. |
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Yes I suppose it could...never seen it personally. When dry firing pull the charging handle back fully and let it go.If you don't like the clank of the BCG going into battery,then do as you say you have been and give the foward assist a couple love taps.You just want to make sure your BCG is fully in battery. Alternately you could also use snap caps/dummy rounds and use the action as its supposed to be,i.e. letting the BCG fly home from full stroke. Also if this is obviously the cause,your firing pin is fine.If the peening on the spool bothers you,dress the peened ridge down with sandpaper or a file.Personally I wouldn't worry about it.Good to have spares though. Quoted:
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Firing pin is supposed to stop on the bolt tail,not against the carrier. Do a test...with BCG in hand pull bolt foward to unlocked position.Using a finger press the firing pin foward and hold it against the carrier.Now press the bolt reward to in battery position.As the bolt is pushed back into the carrier you will feel it push the firing pin back. If it does not test correctly may be an issue with the carrier or the bolt.If the bolt tail is short you should also check firing pin protrusion.. Only other way I could see the firing pin spool being peened that way is if you are firing the rifle without the BCG being in full battery. Have you been riding the charging handle and dry firing alot? I did the test you described, pushing the bolt back does move the firing pin back. I do dry fire a bit, but not excessively. I bring the charge handle back enough to reset the hammer, then fire a bit, as to feel trigger reset. could this cause it? Yes I suppose it could...never seen it personally. When dry firing pull the charging handle back fully and let it go.If you don't like the clank of the BCG going into battery,then do as you say you have been and give the foward assist a couple love taps.You just want to make sure your BCG is fully in battery. Alternately you could also use snap caps/dummy rounds and use the action as its supposed to be,i.e. letting the BCG fly home from full stroke. Also if this is obviously the cause,your firing pin is fine.If the peening on the spool bothers you,dress the peened ridge down with sandpaper or a file.Personally I wouldn't worry about it.Good to have spares though. hmmm I have never thought of dry firing possibly causing this. I would say it is the culprit. I put a good bit of rounds through it today, with no problems. Oh well, Ill take this one out for a spare, and check the new one occasionally for the same problem. I will stop dry firing in this manner, and see if it stops peening. |
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Dry firing is not going to damage anything. That wear is not normal. Something is out of spec. It potentially could if the carrier isn't fully in battery from following the charging handle home slowly, and the flange of the pin is hitting the carrier instead of the bolt tail. It shouldn't be doing that if the pin is the proper hardness, though. What does the other side of the flange look like? Is it still flat, or is it just the edge that is being peened? Some firing pin pockets I've seen in carriers have a radius in the bottom where the flange could be contacting when the carrier retracts... |
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Semi normal,
On a M-16 FP with shrouded carrier, the diameter of the stop collar is much larger, and have a larger bearing area will not peen so much. On a semi FP that has a ramped carrier instead, the stop collar is much narrow to not protrude past the carrier ramp, so you get that slight peening as the carrier slams into the face of the stop collar as the carrier comes back during cycle. Just chuck the back end of the FP in a drill, and spin file the now peen edge off. Also, if you put a slight taper to edge, it will slow the further peen'g way down as well. |
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Military weapons get dry fired a lot and I never saw this happen. Agreed. I believe,just maybe, the issue he is having is the way he was partially charging/riding CH the weapon and the BC may not be fully foward in battery....i.e. hammer striking firing pin, and the firing pin collar slams into the carrier completing the in battery stroke. Or it could be as Dano states above. Good reson to prefer large spool firing pins. |
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The bottom of the FP is still flat. ETA It seems BCM would have included a full auto firing pin, since their BCs are FA right? can someone post pics of the difference Again, it just the OD of the firing pin stop collar, with the M-16 wider and would protrude past the ramp of a semi carrier. The edge peen'g is coming from the edges around the back of the carrier channel for the bolt tail that protrudes out the back of the carrier. So with the bolt locked home and dry fired, the FP stop collar is going to strike the bolt tail alone. Over time, it can create a ring type indent on the face of the stop collar, but not the very edge of the FP stop collar edge. When the carrier comes back, the bolt tail moves forward inside the back of the carrier, and now the tail channel in the back of the carrier is what is pulling the FP back, slamming into as the bolt goes to lock up. Again, the M-16 FP collar is wider so the edge of the carrier bolt channel has less effect on the pin (edges), while the smaller FP stop carrier with it smaller width, has less area to accept the force, which cause the FP edges to peen. So on that note, remove the peen edge via spin filing, and slightly the front face edge at the same time. 
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Unless you have a carrier that has a radius in the firing pin pocket and the larger flange would hit it, whereas the smaller AR15 flange wouldn't. Quoted:
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Good reson to prefer large spool firing pins. Unless you have a carrier that has a radius in the firing pin pocket and the larger flange would hit it, whereas the smaller AR15 flange wouldn't. In my experience Ive never seen that combination of tolerances.The standard firing pin per design is the large spool firing pin.The smaller "AR15" type small spool firing pin was used in the unshrouded carriers. Now,as Dano has discussed and shown you have to have the small spool firing pins in the unshrouded carriers. Otherwise the large spools pins are standard in most of the good quality BCG's nowadays,for example Colt,DD,LMT,and PSA,as well as Spikes etc.. |
And again, a Larger diameter M-16 FP will only work with a shrouded carrier.
In a non shrouded carrier, the larger OD of the stop collar will protrude beyound the ramp of the carrier, and cause nothing but jamming problems, either with a rounded top hammer, or the L step cut hammer. As for if the carrier is FA or not, that has to do with the back sear trip edge, and if it is correct or not. 
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From that picture, of the different pins, I believe i have the AR15 FP. I could be wrong though. My BC is shrouded Could be, and if you call BCM, chances are they will just send you a new M-16 firing pin replacement for free. This will leave you with a M-16 FP in the rifle, and a semi FP that you can clean up and have for a back up if needed down the road. |
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Could be, and if you call BCM, chances are they will just send you a new M-16 firing pin replacement for free. This will leave you with a M-16 FP in the rifle, and a semi FP that you can clean up and have for a back up if needed down the road. Quoted:
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From that picture, of the different pins, I believe i have the AR15 FP. I could be wrong though. My BC is shrouded Could be, and if you call BCM, chances are they will just send you a new M-16 firing pin replacement for free. This will leave you with a M-16 FP in the rifle, and a semi FP that you can clean up and have for a back up if needed down the road. I've emailed BCM about the problem. After speaking with them about the problem and sending a picture, this was their response [email protected] Oct 15 (1 day ago) If you experience any issues with the BCG let us know. You should be good to go at this point. Thank you. [email protected] Bravo Company USA, Inc. www.Bravocompanyusa.com www.bravocompanyMFG.com I am slightly disappointed about their response. Also while ordering a FA bolt carrier group, wouldnt you expect a M16 Firing Pin? |
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I've emailed BCM about the problem. After speaking with them about the problem and sending a picture, this was their response [email protected] Oct 15 (1 day ago) If you experience any issues with the BCG let us know. You should be good to go at this point. Thank you. [email protected] Bravo Company USA, Inc. www.Bravocompanyusa.com www.bravocompanyMFG.com I am slightly disappointed about their response. Also while ordering a FA bolt carrier group, wouldnt you expect a M16 Firing Pin? Quoted:
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From that picture, of the different pins, I believe i have the AR15 FP. I could be wrong though. My BC is shrouded Could be, and if you call BCM, chances are they will just send you a new M-16 firing pin replacement for free. This will leave you with a M-16 FP in the rifle, and a semi FP that you can clean up and have for a back up if needed down the road. I've emailed BCM about the problem. After speaking with them about the problem and sending a picture, this was their response [email protected] Oct 15 (1 day ago) If you experience any issues with the BCG let us know. You should be good to go at this point. Thank you. [email protected] Bravo Company USA, Inc. www.Bravocompanyusa.com www.bravocompanyMFG.com I am slightly disappointed about their response. Also while ordering a FA bolt carrier group, wouldnt you expect a M16 Firing Pin? I don't think BCM has ever used the large spool firing pins in their BCG's.I don't know why they don't,guess its just what they supply. Not that big of a deal either way really...I'd run what you have. Do some shopping/calling around for a large spool firing pin if you want one....Colt,DD,LMT etc.. http://www.brownells.com/rifle-parts/bolt-parts/firing-pins/firing-pin-prod4828.aspx |
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