Other than re-contouring an A2 barrel or paying that guy on GB $600 for one of his Colt barrels, this is one of the only choices available right now if you want the A1 profile and 1/7 twist for 77gr SMK's. So, I ordered one:
link to barrel . The following is an initital inspection of the product. Assembly and range testing will follow in a later thread. I must say up front I sent the first barrel back I got from them - the chamber was rough and really tight on a GO headspace gauge, which I attribute to high scratches and galling on the shoulder of the chamber. Secondly, there was significant bore runout at the muzzle and the crown was not finished very well. The barrel would probably have functioned with all of this, but I was not satisfied, so of it went. The lady on the phone was gracious and took care of it. The new barrel shows significantly better workmanship. There was a new "QC Passed" sticker on the new barrel:
The barrels come literally swimming in cutting fluid. Be prepared to wipe clean for initial inspection:
Wt = 1 lb 12 oz:
Barrel identification is stamped radially around the end of the barrel. This will turn off some immediately for retro builds. The crown is excellent, and the bore was visually concentric with the barrel - it passed the "roll" test. Whatever they use to mask for parkerizing leaves the crown and some of the threading uncoated at the muzzle. The extension was poorly masked, which left a swath of phosphate coating up on the pilot diameter. They tout a "Nickel Boron M4 Feed Ramped barrel extension", so maybe that is why they didn't park the whole extension.
Passed head space check:
Uh-oh. Inspection revealed chips and flashing in the gas port - about 50% blocked:
Carefully reamed out with a drill bit by hand, but "QC Passed"? Always check that damned port. Anyway, there were no significant burrs showing in the bore where the port enters.
Port diam gauged .094. That is out of spec for a A1 barrel, but not by much:
OK, next check: slide my take-off A1 FSB up on the barrel - nope wont go on:
Mic reveals dia out of spec: .6264 measured vs .6238 from the drawing = .0026 over size. This might piss off some people. I'll just ream the FSB since it is not coated anyway, and preserve the park on the barrel:
Next, try to slide extension into known good Colt upper I have used successfully w/several barrels. Nope, wont slide in, but it's close. Mic reveals extension outer dia is out of spec: : .9995 measured vs .9987 from the drawing = .0008 oversized. That may not sound much to you, but 8 tenths over size is a bitch press fit for hand assembly. I will not touch that upper - so some work will be involved in getting this to work:
Lastly, eyeball checking the gas port alignment with the extension pin indicates tilt to the left:
SUMMARY:
This ain't no freakin' $500 Bart-krieg-veske barrel, so you cant get your panties in a wad if there are issues with it. I don't like barrels with the extension and fsb diameter turned too large - a pet peeve which you may not care about - just my 2c - it's not insurmountable. Port tilt bugs me, but I think that will be ok. I have not shot it yet, so can't comment yet on feeding, function, accuracy, etc.
Pros
1/7 twist A1 answers pent-up need (why won't more mfgs jump in?)
available and in stock
low cost
customer service - nice lady on phone
Cons
dont expect to just slap it on - cleaning and inpection needed before firing
some fitting needed - out of spec here and there
mfg stamps on end of barrel - would be better under the handguards
why not park the whole freakin barrel instead of leaving spots (maybe "nickel boron" doesn't need it? dont know).