I have been lurking around the board for a few weeks and decided I ought to get a little more involved. There is some great information here. Thanks to all of you for your comments and good advice.
I have a question about the fluted barrel that is on one of my AR’s. It is on my Bushmaster XM-15 modular m-4 style rifle. It is chrome lined, fluted, and marked Nato 5.56 1/9 which I undrstand, but I wonder if this is a Bushmaster barrel, 4140 or 4150, etc?
I’ll bet that Bushamster will know and they will more than likely answer. I had an enquiry as well about some stuff and their tech people gave me the info straight away.
According to Wiki, Bushmaster barrels are 4150, chrome lined – unless they are “special” barrels like stainless steel or broach cut match barrels, etc.:
…I see several references at Bushmaster.com that most of their barrels are 4150. They just don’t specifically mention this fluted barrel. Another hint this particular barrel may be 4150 is that it’s spec’s shows that it contains vanadium.
Probably the only way to get to the bottom of it for sure is to call them and give them the part number. If it is 4150, good. If it is 4140, that’s still fine. The difference in performance would be just a small margin – noticeable only at end-of-life. A point at which you would have had to have bought ammo equalling the cost of about a 40 barrels. So the ammo cost is a much greater driver in the life cycle expense than the barrel. Also assuming this isn’t a class 3 weapon, you will never reach maximum barrel temperatures. Besides that, it is probably 4150.
Just guys talking, but I think the only way to get to the bottom of it is to send it in to be destroyed and analyzed for composition, like BCM did with theirs and Colts
But seriously, you may never really know for sure. Unlike finding out if it has a true 5.56 chamber, which you can hit with a reamer and Be Sure.
for this: gotm4 Offline
STAFF Join Date: Jun 2006
Location: Northern, VA
Posts: 6,060
Quote:
Originally Posted by GONIF
YOU DON’T WANT TO USE A REAMER ON A CHROMED CHAMBER.
Sure you can, how do I know? I’ve seen me do it.
It wears the reamer out a little faster but doesn’t harm the life of the barrel. I’ve done more than 100 chrome lined barrels. Barrel chrome lining isn’t like the chrome on the bumper of a 57 Chevy.
