08-14-2011, 06:45 PM
I really like my Mega uppers but man are they tight, I expect to allow for a range of tolerances on barrel extensions. My first HD billet upper provided a excellent fit after much fitting. A gunsmith buddy even commented about it when I asked him to check my work before torquing the barrel nut.
This last Mega Monolithic is a really nice piece but it caused a bit of teeth gnashing mostly because of the difficulty reaching the area that needed attention. I solved my problem with judicious use of a brake cylinder hone. A few spins of the drill, rinse with contact cleaner, and attempt barrel fitment; several times. Final fit still required a few taps with a rubber mallet.
An 8 1/4" hone inserted from the rear of the receiver was just right. With the upper clamped upside down in a vise care should be taken not to allow the hone to expand on the threads for the barrel nut. The drill chuck looks to be about 7/8" which was easy to keep centered while using about 1/2" stroke on the stones which were 1 1/4" in length.
Thanks for everyone's suggestion, pictures soon!
-Will-
This last Mega Monolithic is a really nice piece but it caused a bit of teeth gnashing mostly because of the difficulty reaching the area that needed attention. I solved my problem with judicious use of a brake cylinder hone. A few spins of the drill, rinse with contact cleaner, and attempt barrel fitment; several times. Final fit still required a few taps with a rubber mallet.
An 8 1/4" hone inserted from the rear of the receiver was just right. With the upper clamped upside down in a vise care should be taken not to allow the hone to expand on the threads for the barrel nut. The drill chuck looks to be about 7/8" which was easy to keep centered while using about 1/2" stroke on the stones which were 1 1/4" in length.
Thanks for everyone's suggestion, pictures soon!
-Will-