Log in

View Full Version : 300/223 AR-15 locking lug modification


gt3499a
07-12-2005, 11:59 PM
I am having a locking lug, magazine, or bullet profile problem.

Problem: the front of the bullet sticks in the locking lugs. Sometimes slamming the bolt will cause it to chamber, but more often it just seats the bullet deeper. :mad:

Equipment: Armalite upper reciever, 11.5" shilen barrel, 6" gas port possition, orlite mags (with and with internal guidance ridge removed), bushmaster 30 rnd mags, dpms chromed bolt and carrier, Davis brass, 180 grain pointed soft point remington core-lokt

Tried: shortening bullet seat depth, different mags, lube, cursing, hand chambering a round - closing bolt - inserting mag (sometimes works for a couple rounds),

Info: I bought this upper used after waiting for 10 months for Olympic to make me a barrel and still being quoted another 3 or 4 months. It produces good accuracy but has to be hand loaded to work properly. The guy that I bought it from told me that it would run f/a no problem with subsonics, and maybe it did for him, but he was using a more rounded 220 grain projectile. It seems that the bullet profile is what keeps getting me in trouble with the locking lugs. It just digs in and catched. He had previously smoothed and rounded the bottom 2 locking lugs with something like a dremel (undisclosed before sale).

How much of the locking lugs can you remove safely? Could you wallow it out so that the 2 bottom lug areas were one cupped feed ramp? :confused:

Dan

AR15barrels
07-13-2005, 01:26 AM
Lose the softpoints.
You are going to want FMJ's, or something where the front of the bullet is more closed up.
As to feedramp mods, here is what M4 ramps look like:
www.ar15barrels.com/gfx/feedramps.jpg
Should be no problem to cut the ramps deeper and blend into the receiver.
No need to eliminate the bottom locking lugs, the rounds feed off of the two feed lips on the mag, alternating from the left and right.

Randall
www.ar15barrels.com