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Posted: 9/26/2005 9:32:17 PM EDT
M4 profile or HBAR. Which is better?  I have a Bushmaster XM15E2S and a friend has a RRA M4.  Mine is the 1/9 twist and his is the 1/7.  I want the removable carry handle and he wants to trade. My question is is there a disadvantage to the 1/7?  Oh and is that a fair trade? Both have collapseable stocks and look the same except for carry handles and barrels. Is RRA better than my Bushy?
Link Posted: 9/26/2005 9:46:12 PM EDT
HBAR vs govt profile I prefer the lighter govt profile.

Only reason not to have a 1/7 twist is if you want to shoot bullets lighter than 55gr.

RRA barrels are 4140 steel while bushmaster's are 4150 steel. Make sure the RRA is chromelined.
Link Posted: 9/27/2005 4:02:23 AM EDT

Originally Posted By topgunpilot20:
HBAR vs govt profile I prefer the lighter govt profile.

Only reason not to have a 1/7 twist is if you want to shoot bullets lighter than 55gr.
actually you can shoot down to 40grn. rounds through the 1/7 twist barrel (my 1/7s shoot the 45grn HPs by Winchester excellently) and up to the 77grn rounds

RRA barrels are 4140 steel while bushmaster's are 4150 steel. Make sure the RRA is chromelined.
majority of the RRA 1/7s are chrome-lined, IIRC



Mike
Link Posted: 9/27/2005 12:04:40 PM EDT

Originally Posted By mr_wilson:

Originally Posted By topgunpilot20:
HBAR vs govt profile I prefer the lighter govt profile.

Only reason not to have a 1/7 twist is if you want to shoot bullets lighter than 55gr.
actually you can shoot down to 40grn. rounds through the 1/7 twist barrel (my 1/7s shoot the 45grn HPs by Winchester excellently) and up to the 77grn rounds

RRA barrels are 4140 steel while bushmaster's are 4150 steel. Make sure the RRA is chromelined.
majority of the RRA 1/7s are chrome-lined, IIRC



Mike

RRA makes 1/7s? I thought they only made 1/9 and 1/8.
Link Posted: 9/27/2005 4:48:17 PM EDT
How about the quality on the 2 guns?  About the same?
Link Posted: 9/27/2005 10:58:32 PM EDT
Craftsmanship is about the same, the BM just has harder steel.
Link Posted: 9/28/2005 4:53:55 AM EDT

Originally Posted By topgunpilot20:
RRA makes 1/7s? I thought they only made 1/9 and 1/8.




Believe if you'll check w/ Pete @ Legal Transfers you'll find that although hard to get RRA does have 1/7 twist uppers (chrome-lined).

Mike
Link Posted: 10/14/2005 7:11:32 AM EDT
Since I dont carry my AR for extended periods of time and usually shoot 55+ grain ammo I shoud just stick wit the Bushmaster?
Link Posted: 10/14/2005 8:19:02 AM EDT
If you do trade, just trade upper halves.  That way you keep your own serial number.  The lowers are equal quality, except his RRA probably has the 2-stage trigger which would be lighter than yours.

If you don't shoot ammo heavier than 69gr then you have nothing to gain from the 1/7 twist.  If his is a true M4 profile it'll be about 1/2 lb lighter than your HBAR.  If it's new enough to to be 1/7 twist then it probably is, but I think RRA used to make (maybe still does?) barrels with the M4 cut in front of the front sight for the look but still HBARs under the handguards, which would weigh just as much as yours.  Bushmaster uses 4150 steel which is better than the 4140 RRA uses, but the difference is in how it handles high heat so you wouldn't notice unless you shot a lot of rapid fire.  ("Normal" non-AR rifle barrels are 4140.)  Bushmaster barrels are chrome-lined, which is easier to clean and lasts a lot longer.  Not all RRAs are, but his might be.  Personally, I want to be able to shoot the 75/77gr ammo and I'd want the lighter profile so I would take his barrel as long as it were chrome-lined.  If his is not chrome-lined, then I'd probably keep the BM.  

Another option would be to just trade upper receivers and keep your own barrel.  The upper receivers are equal quality and if you get the detachable handle too you're probably coming out ahead.  I see you're in Indiana.  Drop over to the Hometown forum and I'm sure you can find somebody there who will help you do the barrel swap if you choose to go that way.
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