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Posted: 8/24/2004 10:47:58 AM EST
[Last Edit: 8/24/2004 10:48:39 AM EST by BeetleBailey]
What's the low-down on using 62 gr. bullets in 1:12 twist barrels? I've read some of the commentary, researched a little (less stabilization, etc.) - but I want to hear it from you informed AR enthusiasts with personal experience.
Thanks.
Link Posted: 8/24/2004 10:49:09 AM EST
The bullet will go weeeeeeeeeeeeeee all over the place.
Link Posted: 8/24/2004 10:59:46 AM EST

Originally Posted By Spooge5150:
The bullet will go weeeeeeeeeeeeeee all over the place.



LOL. You must be familiar with the threebrain.com squirrel.

Per Maryland shooter's site:
"M855 is too unstable to consider shooting from 1:12 barrels. Bullets which strike sideways probably won't get enough penetration to do any real damage."

Bah, but is this really true?
Link Posted: 8/24/2004 11:03:29 AM EST
This is bad juju.

They will not stabilize past 50 yards. At 100 yards, you WILL get sideways impacts. It can be done, but as stated in the GI manuals, 'Is for operational emergencies only'.


Link Posted: 8/24/2004 11:51:16 AM EST
From Troy's Ammo Oracle

"Q. Can I fire M855/SS-109 in my 1:12 twist barrel?

Yes, but...

...it won't be stabilized properly and after 90-95 yards, it will typically veer off in a random direction. You often won't hit paper at 100 yards. Though it won't hurt your rifle to fire this ammo, it is not recommended. Military manuals warn that it should only be fired in 1:12 twist barrels in a "combat emergency." "

I did it once. 5 shots a 100 yards 3 keyholes. So yes it's bad juju.
Link Posted: 8/24/2004 11:59:05 AM EST
We tried that at 200 yards with 77gr and 62gr in a REALLY old Colt. The 62gr was hitting the berm instead of the target. Or going by it. The 77gr was flipping so bad you could see it. Pretty funny.
Link Posted: 8/24/2004 12:00:19 PM EST
Link Posted: 8/24/2004 12:12:44 PM EST
Well, I guess that answers that. Thanks folks.
Link Posted: 8/24/2004 12:30:26 PM EST
History, just before Desert Storm, many National Guard units still had old 1x12 twist rifles (in which they used 55 gr FMJ's), there was a big rush to equip them with A2's (1x7) so that they could fire M855 ammo, which was what was in the supply chain. Mfgs other than Colt and FN were brought online to fill the gap. Without all the AR-15 "clone" manufacturers created by the civilian market, this would not have been possible. A total ban on semiauto rifles (which is what they really wanted) would have shut down these smaller mfg's, and this would not have been possible in future wars.

Look at the M9 (Beretta) mag problems, which were aggravated by the AWB.
Link Posted: 8/24/2004 12:52:39 PM EST

Originally Posted By BeetleBailey:

Originally Posted By Spooge5150:
The bullet will go weeeeeeeeeeeeeee all over the place.



LOL. You must be familiar with the threebrain.com squirrel.

Per Maryland shooter's site:
"M855 is too unstable to consider shooting from 1:12 barrels. Bullets which strike sideways probably won't get enough penetration to do any real damage."

Bah, but is this really true?



AND THERE WAS THIS GUY... AND I WAS LIKE "YO MOTHA FUCKAH... WEEEEEE!!"

S
Link Posted: 8/24/2004 1:30:23 PM EST

Originally Posted By BeetleBailey:
Bah, but is this really true?


Yes it is.

Besides being covered in the back of FM23-9, those of us who've done it have see the problems.

I've seen sideways hits on paper as close at 25 yards, when I was trying to help a guardsman who was zeroing an old SP1 with M855. When he couldn't hold a group (and had those elongated holes) I checked his ammo and barrel. As soon as he switched to some 55gr the rifle held good groups.
Link Posted: 8/24/2004 7:47:07 PM EST
You can get all this straight by reading the AMMO ORACLE from front to back several times. Summary:

Length and balance, not weight, determine what twist a bullet needs.

1:12 55 - 59gr or less only effectively...heavier only in freak incidents. all M193.

1:9 all up to about 66 or 69 grains including 855, but not 856(tracer compliment to 855)

M855 (green tip) has to be stabilized like a 68or so grain bullet because is it longer and less dense due the the metal and tungsten core when compared to a standard 62 gr bullet

M856 (red tip) is extremely long, but still only 62 grains. Its length requires a 1:7 twist to be reliably stabalize, but 1:8 might do the trick.

1:7 Shoot anything but light loads. 40 and some 50 grain varmint loads might be spun apart.
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