I just picked up a Bushmaster AR15 with the 16" barrel and 1-9 twist.
I have everything to reload except for the bullets. I was curious what people have experienced to be optimum weight for this twist for the best accuracy. I have some 55 grain FMJ factory ammo to shoot through it right now, but will be reloading for it SOON!!!
I am thinking the 62 or 55 FMJ will be just fine out to 300 yards for good accuracy?
Thanks,
Marcial
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With a 9 twist the heaviest you can go would be 70 grains. over that you risk bullet instability. This instability could show up at 100 yard or at great distances depending on to what extent yopu go over 70 grains. Holes on target would be oblong in shape not perfect round holes. term for the oblong bullet holes is key holeing.
I had some Sierra 50 grain varminter SPTs in the cabinet, so I gave them a shot with 25.0 grains of IMR 4895 and CCI 400 primers. I had it dialed in good at 25 yards, and was hitting a barrel at about 520 the other day.
The wind was blowing too bad yesterday to shoot a group at 100 yards, but I will try that soon.
I will try not to move the sights much, as this is my duty gun also, and I need to make sure it is sighted in to that ammo (which doesn't shoot worth a crap anyway, thats another story).
I am pretty pumped about loading for this gun now!
Later,
Marcial
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I have a Bushmaster with a 1:9" twist as well and I shoot the Sierra 69gr Match Kings. They are about the heaviest bullets that group well out of my rifle so it's what I stick with. I used to have an Carbine upper with a 1:7" twist so I wanted a load I could shoot out of both uppers.
First off Congrats on the new AR
I have a 20in w/ a 1 in 9 twist I know yours is 16. But had to share my ar loves the IMR 4895 with nos 50gr bt. 25.6 grs with cci 450 primers and a oal of 2.260 it's almost perfect 3 @ a 100 inside a quater. Been out of that powder for about 8 months and just found 2lbs a little while ago. Didn't know what I was gonna do but all better now
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Every day above ground is a good day especially when it's one day closer to hunting season.
I have been loading some 50 Gr. Sierra Varminter over 25.0 grains of the IMR 4895. It has also been rare around here, but I grabbed up the last two pounds I have seen. I have yet to see a real tight group with my AR, but I am shooting with only the open sights, so I don't expect anything tighter that about 2" at 100 yards.
The load does function well, which I think is key, even if I don't get the tightest groups.
Later,
Marcial
__________________
Records were made to be broken
2011 Spring Turkey Contest Team 1 Kee Kee Krew
2010 Spring Turkey Contest Team 8 Kee Kee Krew Winners