I have recently rebuilt my AR15 from It’s original build which was a DPMS lower receiver with Model 1 Sales parts kit, to a carbine using parts from DPMS and Bushmaster.
Ever since i first built the gun, I’ve notice that the pins in the lower receiver for the fire control group (the Model 1 Sales lower parts kit are still on the rifle, i plan on replacing them with Bushmaster lower receiver parts), will turn every time i pull the trigger.
Will these pins rotating every time i pull the trigger wear out the holes in the lower receiver and should these pins rotating, stop rotating when i replace them with a better quality, Bushmaster lower parts kit?
Is it normal for these pins to rotate when the trigger is pulled?
Ehh not really normal. The hammer and trigger should be slipping on the pins, not the pins in the receiver. Have you bought the bushmaster parts kit yet, because a Daniel Defense one from BCM might be a better option. It seems really unlikely that the holes in the receiver could be drilled too big, even at DPMS.
This is not good - some rotaition is normal but unless I am misreading this, this seems quite extreme - follow the other guys advice on the parts kits - for grins strip the fcg out and see how easy to rotate pin in the hammer - try going back and fourth between pin for trigger and hammer and let us know there is a difference. Mind you, there is a “spring” in the hammer that is rides in the detent in the middle of the pin.
Everything seem’s to be installed correctly, i think the Model 1 Sales lower receiver part’s are out of spec. I never really cared to much for the Model 1 Sales parts, i was on a budget back then and when the AWB bill was no longer the law of the land, i started a rebuild project to convert it from a post ban A2, to a pre ban M4 style carbine.
Present setup includes the following:
DPMS M4 upper receiver
DPMS lower receiver
DPMS 14.5 inch chrome lined barrel with Bushmaster Phantom permanently welded and pinned on to BATF specs.
Bushmaster bolt carrier and assembly
DPMS M4 stock
Rock River arms M4 handguards
Model 1 Sales lower parts kit (from post ban build, haven’t changed them yet)
I’m in the same boat, I just built a stripped RRA lower receiver with an RRA LPK and the hammer pin rotates with the hammer.
Just wondering if it’s normal, or am I worried over nothing.
EDIT: Corrected the problem myself, I put a drop of oil on each side of the hammer pin and manually cycled the hammer to make sure it’s drowning real good, and it doesn’t rotate anymore.
Markm, i can see the pin’s turn, every time the trigger is pulled.
I’ve been looking at lower parts kit’s, seem’s like LMT are some of the best, but they are hard to find. Can anyone recommend the next best thing to LMT that’s not more then $150.00?. I know one member recommend’s Daniel Defense lower parts kit.
Also, since I’m going with a Osprey Defense piston, it will come with a bolt carrier, but not a bolt assembly. From the reading I’ve done here, I’m considering keeping the bushmaster bolt assembly as an emergency field back up and going with either an LMT bolt assembly or a BCM bolt assembly that has been MPI.
Which of the two are of better quality and has the LMT been MPI?
markm is right it is completely normal for the pin to turn.
G&R tactical sells a LPK that is supposed to be to notch.
It has been over a year since I have seen a LMT LPK.
The only time pin rotation becomes a problem is if you do a lot of full auto fire, or if the pins are not just rotating but actually backing out of receiver. That is why KNS and others offer non-rotating pin sets to keep that from happening. If your pins are not backing out of receiver and you are not doing a high volume amount of shooting, you probably don’t need to worry about it.
I am not trying to be an asshole here. KNS pins and their reputed value have been discussed many times over. They are a waste of money and really serve no purpose other than piece of mind. Tearing apart your lower incorrectly and fucking up the holes with shit that shouldn’t be poked in there will cause more damage then pins rotating.
Please explain why this doesn’t seem to be an issue in the military when firing burst or auto? I have seen and fired M16’s that were VERY old and many rounds put through them.
Pins will not back out of the receiver if the parts are not worn. If you have a worn or damaged “J” spring in the hammer or a worn or incorrectly installed hammer spring then of course it can happen.
