Jksig229
Well-Known Member
what is the reasoning for the twist rate difference in the remington ACR (1:7) and bushmaster ACR (1:9)? forgive my ignorance if this is a dumb question.
Twist Rate difference???
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mr.big
Well-Known Member
9 will work for any of the common loads for the 223 50 gr to 70 gr bullets,,but it is a little to fast for the 40 gr bullets and may or may not work for the 75`s
7 will work on 60 gr up to the 80 gr bullets but will put a lot of stress on lighter bullets and may not be as accurate with light,less than 60 gr bullets,
I would love a 7 twist to shoot the 80 gr and 90 gr Sierra MK but I am getting by real well to 600 with the 69 Sierra and the 9 twist,
just depends on what you want to do with it,,if you are gonna be this side of 500 yards the 9 twist will serve you well with the 69-70 gr bullets and still be really accurate with 50-55 gr bullets,,if you are gonna go past 600 very much you need the 7 twist and use the 75-80 gr bullets.
my 9 will shoot some 75 gr bullets like the Hornady BTHP,,but I have had problems with the 75 gr Amax and the 77 gr Sierra,
7 will work on 60 gr up to the 80 gr bullets but will put a lot of stress on lighter bullets and may not be as accurate with light,less than 60 gr bullets,
I would love a 7 twist to shoot the 80 gr and 90 gr Sierra MK but I am getting by real well to 600 with the 69 Sierra and the 9 twist,
just depends on what you want to do with it,,if you are gonna be this side of 500 yards the 9 twist will serve you well with the 69-70 gr bullets and still be really accurate with 50-55 gr bullets,,if you are gonna go past 600 very much you need the 7 twist and use the 75-80 gr bullets.
my 9 will shoot some 75 gr bullets like the Hornady BTHP,,but I have had problems with the 75 gr Amax and the 77 gr Sierra,
Jksig229
Well-Known Member
Thanks for the info big, I know it was probably a dumb question just wanted to educate my self... Now will the 7 shoot the lighter stuff or does it have problems with that?
Tried some factory load 55gr vmax in my 1:7 mcgowen barreled stevens and they held together, turned out to be very accurate too. not sure all 1:7s will though.
Was expecting to see a puff from them coming apart but was pleasently surprised.
Was expecting to see a puff from them coming apart but was pleasently surprised.
Jksig229
Well-Known Member
Cool cool man I really appreciate the info
infoman jr.
Well-Known Member
The Remington version was developed to shoot military rounds where the Bushmaster is a commercial gun made to shoot (as Mr. Big pointed out) common loads.
Jksig229
Well-Known Member
So I take it military rounds are heavier?
infoman jr.
Well-Known Member
Looks like I learned something too as I'm not part of the Military Products Division. The Bushmaster has a 16.5" barrel and the Remington has a 10.5" or 14.5" barrel, so they found that from a shorter barrel, the 1-7" is more accurate.
