I bought one of the 16" URX III uppers a few months ago, I never fired it. I went to put on my SureFire brake and when I took off the A2 flash hider there looked like what appeared to a good bit a carbon build up on the crown of the barrel. I got the break on with no problem, just thought it was weird to have carbon on a brand new upper in that location. Thanks for any help.
Originally Posted By toolboxluis00100:
all spike tactical uppers are test fire
Bolts & barrels receive a proof round for HP testing. Then, upon final assembly, all uppers and rifles get a 3-5 shot group through them to ensure smooth feed and function. This is done into a dump tank.