Question on what Bushmaster Model I Bought?


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ZombiesAhead
March 20, 2008, 11:43 PM
I bought this - very happy with it but unsure about some specifics:

http://img220.imageshack.us/img220/2562/ar15hz6.jpg

The salesman wasn't sure if this was the heavy barrel model of Patrolman's Carbine. I think it is the HBAR but I'm not sure. Look at the barrel and the taper on the "Patrolman's Carbine."

Patrolman's Carbine:
http://www.bushmaster.com/catalog_xm15_BCWA3F16M4.asp
...16" barrel is chrome lined in both bore and chamber for long wear life and ease of maintenance.

Heavy Barrel Carbine:
http://www.bushmaster.com/catalog_xm15_BCWA3F16.asp
16 Heavy Profile ChromeMoly Vanadium Steel Barrel - Chrome lined in both Bore and Chamber for easy chambering, long life and quick clean-up.

Assuming it is the HBAR, what is the difference between my "ChromeMoly Vanadium Steel Barrel - Chrome lined in both Bore and Chamber" and the other rifle's "chrome lined in both bore and chamber"?

This seems nonsensical. Bushmaster tells me that the Patrolman's Carbine is "chrome lined in both bore and chamber" but my HBAR is a "ChromeMoly Vanadium Steel - chrome lined in both bore and chamber."

Huh? :scrutiny: Any ideas? Where does the "ChromeMoly Vanadium" fit in if both rifles have chrome-lined bores and chambers?

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Magnuumpwr
March 21, 2008, 12:47 AM
ChromeMoly Vanadium deals with the quality of the barrel itself. As far as your question about it being a patrol or HB carbine, your pic doesn't have enough lighting to tell.

ZombiesAhead
March 21, 2008, 01:48 AM
So is ChromeMoly vanadium a better "type" of chrome lining? Or is this what the mass of the barrel is made of and then a generic/standard "chrome" is used to line the inside?

Sorry about the bad picture - I was trying to show that the barrel is the same diameter all the way down into the sight block. As I looked more and more at it I've come to the conclusion it is the heavy barrel - the other 16" non-dissipator models all have a taper before the front sight post (originally designed to mount a grenade launcher I believe).

mc223
March 21, 2008, 02:54 AM
The barrel material is ChromeMoly Vanadium Steel. The internals of the barrel are chrome plated. Wiith the obvious difference of stainless, all Bushmaster barrels are ChromeMoly Vanadium Steel.
It looks like the A3 heavy barrel carbine to me.

Quack
March 21, 2008, 03:00 AM
http://www.bushmaster.com/faqs.asp#22

"...but we use mil. spec. 4150 ordnance steel."

and...

http://www.ar15.com/lite/topic.html?b=2&f=138&t=148891

"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."

Bobarino
March 21, 2008, 03:07 AM
XM15-E2S 4150 chrome lined HBAR, 1:9 twist, A3 flat top, A2 flashhider. exactly the same as mine. (when i bought it anyway). i love mine. most steel alloys have Cr and Va in them hence the Chrome Vanadium. here's a link to the formula for it. http://www.efunda.com/materials/alloys/alloy_steels/show_alloy.cfm?ID=AISI_4150&prop=all&Page_Title=AISI%204150

Bobby

TheDisturbed1
March 21, 2008, 03:08 AM
that looks like my XM15-E2S :)

EDIT: Bobarino beat me to it :p

And they are great guns IMO ;)

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