Warning

 

Close

Confirm Action

Are you sure you wish to do this?

Confirm Cancel
Member Login
Posted: 7/9/2003 7:11:58 PM EDT
[Last Edit: 7/9/2003 7:30:33 PM EDT by cnatra]

I'm thinking seriously about ordering one of the 14.5" DPMS 1x7 M4 barrels from CMMG & I'm wondering if I need to be concerned about the faster twist with 55gr ammo.

Most of my ammo is 55gr (XM193 or Q131a) but I have some IMI M855 too.
All of my current AR's are 1x9 barrels.

So get the 1x7 DPMS barrel or order & wait for a 1x9 Bushmaster M4 barrel ??

Thanks
Link Posted: 7/9/2003 8:03:10 PM EDT
Should be fine for short distances but at longer ranges the 1:7 will over spin it...look through here, answers anything on bullets and twists [url]www.ammo-oracle.com[/url]
Link Posted: 7/9/2003 8:06:17 PM EDT
You can also spin them so hard they fly apart. That's rare, but it happens if you are dealing with very tight twists and very high velocities. When fired at 3200 fps in a 1-in-7 twist rifle, a round is rotating at over 300,000 rpm when it leaves the muzzle. Light, thin-jacketed varmint bullets (i.e., 40gr Hornady TNT or Federal Blitz bullets) often can't take that much spin and will pull themselves apart.
View Quote
Just looked at it myself the answer should be explained here...[url]http://www.ammo-oracle.com/#twists[/url]
Link Posted: 7/9/2003 8:07:50 PM EDT
One more time...
Q. OK, that's complex. Simple question: Can I fire M193 ammo in my 1:7 or 1:9 twist barrel? Yes. M193 is essentially a "universal" round; able to be stabilized by barrels with twists between 1:14 and 1:7.
View Quote
..haha I was wrong twice
Link Posted: 7/9/2003 8:11:39 PM EDT
I guess I should have taken the time to read Brouhaha & Tatjana dissertation again . I thought about posting there but figured I'd get more responses here. Thanks
Link Posted: 7/9/2003 8:16:20 PM EDT
I did some more reading, it says...
Q. Will M193 be accurate in a 1:7 or 1:9 twist barrel? It may be marginally less accurate due to the fast twist rate, particularly in 1:7 twist barrels.
View Quote
Been a while since I've read any of that...seems like I need to hit the books errr webpages. How times have changed...
Link Posted: 7/9/2003 8:21:40 PM EDT
Originally Posted By tivoli410: I did some more reading, it says...
Q. Will M193 be accurate in a 1:7 or 1:9 twist barrel? It may be marginally less accurate due to the fast twist rate, particularly in 1:7 twist barrels.
View Quote
Been a while since I've read any of that...seems like I need to hit the books errr webpages. How times have changed...
View Quote
yeah, I may just stick with the 1x9 then I wonder how long it will take to get a Bushy M4 barrel [?]
Link Posted: 7/9/2003 8:25:26 PM EDT
If its worth doin, its worth doin right...I always go by this and when I don't I regret it later
Link Posted: 7/9/2003 9:52:09 PM EDT
cnatra, > I wonder how long it will take to get a Bushy M4 barrel? i recently (March) purchased a bushmaster full 16" M4 profile "blunt" (no brake) post ban upper assy. they call it the "patrolman's carbine upper" or some such. it took about 3 weeks from the time i talked to a dealer to when i got it. i'm not sure if getting just the barrel will be different in terms of delivery. just trying to give you a data point. talk to Chris Rose at Eagle Arms (you can find him over in the EE section) -- he hooked me up nicely with the BM 16" upper. ar-jedi
Link Posted: 7/9/2003 10:07:40 PM EDT
Originally Posted By ar-jedi: talk to Chris Rose at Eagle Arms (you can find him over in the EE section) -- he hooked me up nicely with the BM 16" upper.
View Quote
Thanks!
Top Top