I have a DPMS lo pro 16" HB with about 300 rounds through it. When I lock the bolt open and then tap the butt hard on the floor, bolt closes. Discovered this when setting the rifle in the safe after a clean/lube session.
What have I done wrong in reassembly?
BTW, not going to range until I get this straightened out.
Thanks
seabreeze
You bring the rifle downward your energy is imparted to the rifle. It is now in motion.
When the stock “taps” the ground the rifle stops for a moment and bounces up slightly. Any part of the weapon that is not fixed in place on the rifle continues to move downward/rearward for a moment (ie. the bcg and buffer).
When the bcg and buffer move downward/rearward the bottom bolt lug loses contact with the bolt catch, this allows the bolt catch spring to push or lever the bolt catch back to its resting position out of the way of the bolt lugs.
The bolt only travels back/down for a very short distance before it is pushed forward/upward into battery.
In short your rifle is most likely fine.
silly physics
Just in case this is legit…
If this is happening without an empty magazine in the well, by tapping the butt of the rifle hard against the ground you are causing the carrier to shift back into the receiver extension enough to take pressure off of the bolt catch which is now jostled out of position (also due to the spring) to catch the carrier thus releasing it.
If this is happening with an empty magazine inserted, then in addition to the above, the magazine follower is out of spec or canted/tilted somehow preventing proper contact with the bolt catch, the magazine spring is weak and in need of replacement or your bolt catch is installed wrong or out of spec.
Thanks for the replies. May be good to go, but don’t remember M1 and m14 doing this so it made me nervous. :o)
No mag was in place.
seabreeze
–>Insert corny joke about keyboard malfrunction here
The Garand won’t do it because of how it locks back.
You best betcha Hong Kong believe an M14 will! Without a mag in the well, the bolt hold has a tenuous grip on the bolt at best. Every time I delude myself I can run a cleaning rod down the bore with just the bolt locked back, I’m reminded of this fact. Just a little tap on the bolt face with the cleaning rod tip…
In any case, your AR is normal
Yes, just don’t put the rifle away in that condition