View Full Version : AR15/M16 Bolt Upgrade - packrat
Greetings,
I'm considering a Bolt Carrier Group upgrade. The only thing I've done so far is to replace the "cotter pin" type Firing Pin Retainer with the solid type. I attribute some misfires to the cotter pin, firing pin retainer. The problem stopped when I replaced it with the solid type. Can someone suggest other upgrades & Can someone explain "MPI", Magnetic Particle Inspected? I do run through a considerable amount of ammo, if this helps with any advice for me. I appreciate any advice on this matter!!!
You can think of magnetic particle inspection as an "x-ray" for machined parts. It shows any internal flaws in the metal that could lead to failure. However, MPI by itself doesn't mean much if the bolt/barrel hasn't been high-pressure (HP) tested first.
As far as upgrades go, if you're using a carbine I'd suggest the Crane extractor upgrades as sold by BCM or Grant.
Greetings DRich,
Thanks for the response!! I'm familiar with BCM. I noticed their BCM SOPMOD Bolt Upgrade/Rebuild Kit. It seems to be a good deal at $29.95. What do you think?
packrat
You should read this post (http://http://www.m4carbine.net/showthread.php?t=7376). It has tons of info and number 5 is specific to the BCG. I would also suggest to read all of the other stickies as they are also helpful. Good luck.
Greetings bundoc,
For some reason I couldn't get the 'post' to load. I got a response stating "Problem Loading Page" & "Server Not Found". I think it may have something to do with me using Netscape Navigator. I'll keep trying. However, I do appreciate your response!! Have a good one!!!
packrat
spamsammich
06-02-09, 04:58
Greetings,
I'm considering a Bolt Carrier Group upgrade. The only thing I've done so far is to replace the "cotter pin" type Firing Pin Retainer with the solid type. I attribute some misfires to the cotter pin, firing pin retainer. The problem stopped when I replaced it with the solid type. Can someone suggest other upgrades & Can someone explain "MPI", Magnetic Particle Inspected? I do run through a considerable amount of ammo, if this helps with any advice for me. I appreciate any advice on this matter!!!
Can you be more specific about the malfunctions you've been having because of your BCG? I wouldn't go throwing "upgrades" at it until you knew or got as close to knowing what the problem was. Also, what type and brand of ammo were you using?
Greetings spamsammich,
I believe you are correct with regards to the possibility of the ammo causing the problem. I can't remember the brand, but I know it when I see it. It was a foreign 5.56, M855/SS109 62 grain, but it didn't have the green tip. I've never had trouble with Lake City or Winchester 62 grain Penetrator ammo. I swapped out the factory firing pin retainer with a KNS Perma Pin Firing Pin Retainer before firing the weapon again.I did notice that the factory "cotter pin type" firing pin retainer looked rough. As far as any BCG upgrades, I think I'll pick up an extra firing pin & a backup extractor set. Thanks for the response & GOD BLESS OUR TROOPS - ESPECIALLY OUR SNIPERS! I received a bumper sticker from Larue Tactical stating this.
packrat
spamsammich
06-03-09, 19:09
Can you please elaborate on the type of malfunctions you're having?
Greetings bundoc,
For some reason I couldn't get the 'post' to load. I got a response stating "Problem Loading Page" & "Server Not Found". I think it may have something to do with me using Netscape Navigator. I'll keep trying. However, I do appreciate your response!! Have a good one!!!
packrat
The URL in that link has an extra http:// in it. I removed it and the link below will work.
http://www.m4carbine.net/showthread.php?t=7376
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