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Posted: 6/25/2016 8:04:56 PM EDT
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Hey guys long time user of this forum first time poster. I'm hoping someone knows what this is. Long story short as part of a trade I got this rifle length upper with what appears to be a 17" barrel. Markings look like old school Bushmaster but cut down. Rifle length gas system under that JP/Vtac tube, (the previous owner installed that handguard). BCG is Ar-15 type and appears to be parkerized and not phosphated. I tried to take pics of what markings I can see and I hope someone here knows what they are looking at.
Thanks! http://i1248.photobucket.com/albums/hh500/mccormackalan91/Mobile%20Uploads/image_zpswbtsdbtn.jpeg http://i1248.photobucket.com/albums/hh500/mccormackalan91/Mobile%20Uploads/image_zpscztjjtpm.jpeg http://i1248.photobucket.com/albums/hh500/mccormackalan91/Mobile%20Uploads/image_zpskrxvyy1m.jpeg http://i1248.photobucket.com/albums/hh500/mccormackalan91/Mobile%20Uploads/image_zpsit9fx3zc.jpeg http://i1248.photobucket.com/albums/hh500/mccormackalan91/Mobile%20Uploads/image_zps4siwa2mk.jpeg |
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The BMP markings on the barrel in front of the front sight base indicate to me that it's a Bushmaster. As for the 17" length with rifle length gas system, that sounds like a 20" barrel that has been shortened. The key hole marking on the upper receiver is a Cerro forging marking, but that isn't any indicator as to what company machined the forging. Are there any markings on the bolt behind the bolt lugs?
CY6 Greg Sullivan "Sully" SLR15 Rifles TheDefensiveEdge.com (763) 712-0123 |
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Shortened bushmaster barrel, but you really need to pull the Brake and take a good look at the last inch of rifling on the barrel and the crown (read pray like hell that the barrel was not re-threaded with a die and pilot by hand, much less shortened and re-crowned by hand either.
I bring this up, since I just have to shorten and re-crown a 700 barrel that someone screwed up the last inch of rifling a barrel with either a cleaning brush being muzzle loader jammed down the barrel, or someone use a pilot type reamer to the re-crown the barrel as some point instead. Note, screwed up the last inch of rifling is a understatement, since half the lands of the rifling had been ironed dam near flat to the grooves on the rifling instead. To sum it up, my through on anything short of a bullet going down the barrel, lead lapping to unify the rifling from the start, then it's a cleaning rod with a good copper solvent that does not require a lot of scrubbing from that point onward (and always cleaned from the chamber forward to the muzzle, with the cleaning rod never pushed down the muzzle if you don't have to begin with, and never with something on the cleaning rod. FYI, when the 20" barrel is shortened this much, then the gas port has to be adjusted as well. If you run into problems with the rifle not full stroking when it correctly cleaned (including scrubbing the chamber with a chamber brush and CLPt by hand), and the upper receiver bearing areas correctly CLP lubed, then suspect that the gas port was not correctly resized for the shorter barrel. |
| Again thanks for the info. It seems that the gas port was opened up. Ive put probably 750 rounds through it since i got it and the only trouble ive had is after about 250 of m193 switching to wolf 55's basicly trying to make it fail. Even then it short stroked twice in 100rds. When its clean ive run 250 of wolf one afternoon with no problems. This one is more of a range toy for me. Thanks again! |
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