MEMBERS OF THE BUSHMASTER FORUM
I've been getting questions like this for quite a while lately. Bushmaster makes there own barrels, and here is the process.
Comes in as blank steel.
Is then bored & rifled.
Bores are cleaned.
Bores are inspected for pitts,gouges etc. with bore scope 10% inspection.
Bores are air gauged results are recorded for each lot.
Barrels are then heat treated for stress relieve.
After heat treat bores are cleaned and inspected for pitts,gouges etc. with bore scope.
Bores are air gauged recorded and results compared with results prior to heat treat.
Bores are then oiled.
Blanks then are turned down, assemble of bbl extension and headspaced.
Headspace is then checked 100%
GO GAUGE(smaller) is checked with max.bolt(.156) to ensure clearance.
NO GO GAUGE(larger) is checked with min.bolt(.153) to ensure that even with the smallest bolt possible, the bolt will not function.
Chrome lining is then next.
Once chrome is complete bores are cleaned; and inspected 100% with bore scope for complete coverage of chrome. Chrome is to be free from pitts or gouges; and air gauged 100%.
Assembly of front sight base with gas port hole drilled, hand guard cap, barrel nut; and welding of muzzle breaks & flash suppressors if necessary.
Front sight bases ground if needed to assure both ears are the same thickness, hand guard cap is properly placed and plugged to assure proper coverage of phosphate; and keep gas tube hole free of debris.
Barrel then has the Phosphate finish applied.
And finally chambers are polished to assure that the chamber is free of debris; and the complete barrel is visually checked for complete and proper coverage of phosphate.
There is our process, and now all of you know how your Bushmaster barrels got to be so accurate!!