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Posted: 12/4/2008 10:30:55 AM EDT
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I have recently stumbled upon the opportunity to buy a used Colt Target Match rifle that is in very good contition and barely used.
I know that this has been talked about before, but I couldn't find the thread. I remember reading that Colt, LMT, and Novseke were "mil spec" barrles. Does anyone remember what the difference in specification was between military spec and commercial barrels? I think it had to do with the thinkness. For example; Bushmaster VS Colt. Thanks in advance, I'm a noobie to this stuff. |
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The steel and the QC are two big factors, other than the chrome lining.
Colt barrels are MPI and Proof round tested, every single one, whereas Bushmaster only randomly spot checks, despite putting MP on their barrels. BCUSA did a good writeup on what so-called "mil-spec" barrel steel really is. Industry » Bravo Company USA, Inc » Barrel Steel: 4150, 4140, Chrome Moly, Chrome Moly Vanadium 0 BravoCompanyUSA :: 11/22/2005 11:30:58 AM ACST 11595 Barrel Steel ? 4150 Barrel Steel ? Chrome Moly Vanadium ? 4140 Barrel Steel ? There has been a lot of discussions about some of the differences and some of the not-so-differences between these descriptions. This post is in an effort to help clarify some issues as it relates to barrel steel. 4140 grade of steel – The “40” in 4140 is specific to the amount of carbon in the alloy. Generally it is near .40%. Likewise the “50” in 4150 steel is an indicator that the barrel steel has a carbon content near .50% An 11595 barrel steel (Mil-Spec) gets its additional strengthening properties over the common commercial 4140 by one of two ways; more carbon in the steel -or - more carbon with the addition of Vanadium. The specific chemical composition of all Mil-Spec barrel steel is listed below in MIL-B-11595E. This specification outlines the use of barrel steel under 2 inches in diameter for manufacturing barrels for small arms. That encompasses a lot of different small arm weapons. 
When purchasing steel from a mill the certification paperwork and other relevant paperwork usually lists a “Grade” of steel and then adds further details under the heading of “Specifications”. For a Mil-Spec barrel steel; that specification would be listed as MIL-B-11595E. This is to say that not all 4150 steels are considered Mil-Spec. In order for it to be Mil-Spec it would need to be a 4150 grade AND it would have to comply with the specifications listed in 11595. Table One (listed above) shows three types of chemical compositions and ranges for Mil-Spec 4150 barrel steel as defined by 11595. ORD4150, ORD4150-Resulferized, and Chrome-Moly-Vanadium (CMV) should not be confused with the generic term of a Chrome Moly barrel. My opinion and the opinion of the US Government (as defined by the Mil-Spec) is that one of the three is not better than the others. They are all they same and are all 11595 (Mil-Spec) barrel steel. In some descriptions used by steel companies I have seen the Grade of CMV further listed as 41V45, which is a bit more descriptive, but probably just add confusion in this context. |
| What model Match Target would that be? Many 20" MT barrels made '99-'00 had chrome lined chambers, but not in the bore. The steel was the same as the military barrels. If it was the 16.1" MT6530 barrel, it would be completely chrome-lined. Not sure about the 16" HBAR MT barrel chrome lining, though. All the Colt barrels would use the military type steel. |
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