12-13-2013, 03:42 AM
There is no discernible wear from the lapping tool on the raceway inside the upper where the Bolt Carrier rides.
Do not use a torch on a heat-treated aluminum or steel part on the AR15 would be my advice. I have been able to do all the heating necessary with a hot air gun, which is used to loosen up Loc-tite and things of that nature. 7075 aluminum is about as hard as you want for a receiver.
The optimum answer would be to have a receiver that was trued before it is anodized, but I can't think of anything that would degrade the part with a trued face where the anodizing has been lightly skimmed. I've seen military guns where Marines had green-padded their M16A2's to make them "clean" for Command Inspections, and these guns had more exposure so salt and beach sand than the guys carrying them would ever see. Bare aluminum was visible on the upper & lower receivers.
You do have to be mindful of what greases you choose when assembling the upper, as some chemical elements may react with the aluminum. There is the account of the Ranger School student whose barrel fell off in Florida Phase, but they were doing a lot of waterborne patrols and something fishy was particular about his M4.
Do not use a torch on a heat-treated aluminum or steel part on the AR15 would be my advice. I have been able to do all the heating necessary with a hot air gun, which is used to loosen up Loc-tite and things of that nature. 7075 aluminum is about as hard as you want for a receiver.
The optimum answer would be to have a receiver that was trued before it is anodized, but I can't think of anything that would degrade the part with a trued face where the anodizing has been lightly skimmed. I've seen military guns where Marines had green-padded their M16A2's to make them "clean" for Command Inspections, and these guns had more exposure so salt and beach sand than the guys carrying them would ever see. Bare aluminum was visible on the upper & lower receivers.
You do have to be mindful of what greases you choose when assembling the upper, as some chemical elements may react with the aluminum. There is the account of the Ranger School student whose barrel fell off in Florida Phase, but they were doing a lot of waterborne patrols and something fishy was particular about his M4.