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70 grain bullets in AR 15

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02 December 2010, 10:43
ty_falcon
70 grain bullets in AR 15
Has anyone shot the speer 70 grain sp in an AR-15? I have a box of bullets,and according to speer 748 will be the best powder.I'm wanting a good coyote load for my wife.I've shot the 55 gr v max,(very impressive) But for the special occasion of my wife wanting to shoot coyotes,I thought the 70 gr might be good.If you have experience with these bullets your input would be greatly appreciated
02 December 2010, 10:52
ty_falcon
My ar loading has been with 45-50 and 55 gr bullets,which all have been short enough to feed out of the mag. Can the longer bullets be safely seated short enough to feed out of the mag? Thanks
02 December 2010, 19:12
mstarling
Typically the heaviest bullet that can be loaded for semi auto use is 77 gr. Requires a 1:7 or 1:8 twist to stabilize.


Mike

--------------
DRSS, Womper's Club, NRA Life Member/Charter Member NRA Golden Eagles ...
Knifemaker, http://www.mstarling.com
02 December 2010, 19:51
243winxb
The length of the bullet must match the barrels twist. Good info here. http://www.6mmbr.com/223Rem.html
02 December 2010, 22:32
LWD
I believe the 70 grain Speer is short enough to stabilize in slower twist barrels maybe as slow as 1:12"

LWD
02 December 2010, 22:34
LWD
Check this out. http://www.sksboards.com/smf/i...p?topic=58230.0;wap2

LWD
03 December 2010, 10:02
ty_falcon
Thanks for the response. But has anyone used this bullet?
This is a 1:9 twist 20" AR 15
04 December 2010, 00:25
Sam
Ty, I have not shot the Speer 70 gn Varmint Soft Point but Speer lists it as "(1-10" twist or faster)". Your 9" twist should be a great barrel for it. The 70's will sit farther back in the case which reduces powder space but look to me that they should load to magazine length with no problem. The 77's mentioned above are a low drag match bullet. That makes them a longer bullet and harder to stabilize, requiring faster spin. 77 Sierras and 75's from a few different makers are made to be seated to magazine length. There are a couple of 70 grain +, 80's and if you can find them 90's that are loaded too long for a magazine. These are single loaded for long distance slow fire matches. If you have the Speer manual with this bullet in it, it will list the maximum length for the cartridge. Make up a dummy, no primer or powder, to see how it cycles and chambers.


A bad day at the range is better than a good day at work.
05 December 2010, 06:27
vip
quote:
Originally posted by ty_falcon:
Thanks for the response. But has anyone used this bullet?
This is a 1:9 twist 20" AR 15



I use this bullet in my mini mark X (rem 799). The load I use is 25.5gr Varget, Rem 7 1/2 primer, BH match brass. The O.A.L. is 2.290" which puts it .067" off the lands. The barrel is 20" and I think is a 1-12" twist. I didn't chronograph any of these loads but there is no sign of excessive pressure at all and will group around 3/4 moa. There is no sign of keyholing. Since your twist is 9" I'd start a little lower as the pressure would be higher (I suspect). Check Lyman's 48th edition reloading handbook for loads. They have loads for up to 80gr sierra's with 1-12" twist. Good luck.