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Posted: 6/27/2004 3:13:21 PM EDT
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Well after months of screwing with this rifle I have come up with these results. I can consistently get my rifle to shoot less than 1 moa with a five shoot group... even with a hot barrelHell I have even got it down to 1/2 MOA on a good cool day. The problem you ask? Well the only ammo it will do it with is black hills 52 grain sierra match... DAMN IT! ! ! as I go up in grain weight my groups open up with 77 grain being the worst. Culprit? I built this using a 1 in 9-twist barrel because it was super cheap. Well hell, it's like figuring out your kid is smart at algebra but can't spell DOG... Oh well it's my fault. Guess it's time to spring for one of the white oak barrels from ADCO. IPSC_GUY sends |
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I had 3 223 rifles all in 1:9" twist. A Bushy XM2ES Vmatch, Savage 10FP, and a Remington PSS LTR and all liked the 69gr Matchking better than any other bullet I tried in them. Everything I shot out of all three rifles was handloaded by myself and I used Varget powder with Winchester cases and primers. If you're barrel is really short you may not be getting the velocity to spin the heavy bullets fast enough to stabilize them and may have to go to a faster twist. $bob$ |
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1/9 barrels seem to lose their accuracy potential with bullets higher than 70gr. They 1/7 barrels seem to do better with the heavier and longer bullets. Having said that, prepare for the flood of "I shoot 0.xMOA with bullet weights of [> 70]gr out of my 1/9 barrel all the time." I have an SPR upper I built (18" WOA 1/7 ADCO barrel) and it can put 3 of 5 bullets (69gr BTHP Match from Georgia Arms) with their holes joined. The other two are fliers and push my groupings out to 1.5-2MOA. I am hoping that this is due to the mass produced ammo not being exactly the same and not my shooting. I can repeat the 3 of 5 with two fliers all day. I'll give myself credit for one flier out of each group, but the second isn't me. There are times when I know for a fact that I held my point of aim, only to see the bullet hit 1.5" right/left/up/down from that point. I follow that shot with a couple more and they land on top of each other, exactly where I was aiming. I hope it is the ammo. I am going to my own handloads with 69gr SMK and 77gr SMK bullets. I hope this solves the flier issue. Should have some results soon. |
I think the 1x9 is really right on the edge of not being able to stabilize a 77gr. Remember the reason the military went with the 1x7 is to stablize the really long M856 tracers, it wasn't so much that they were heavier is was that they are really long. You might try a 68gr Hornady, 69gr Sierras and 73gr (Berger I think?) also available from Black Hills as reloads. From my experience a faster twist than 1x9 is needed for anything heavier than 69gr bullets. I had a preban 1x9 20" stainless A2 HBar that would 1/2" groups at 100yds non floated barrel w/standard A2 handguards with 69gr reloads in LC brass w/Win 748 and Remington benchrest primers it would shoot 1" groups with M855. You might also want to try different brands of the same weight ammo. Sometimes Federal Gold Medal is more accurate than Black Hills and vice versa even though the loads are almost identical. I think Fulton Armory is selling the Mil Spec Black Hills SPR ammo. |
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the heavier the bullet weight the longer the physical size of the projectile is the longer the projectile gets the quicker the ywist rate needs to be to stabilize the bullet, if you wanna do 77 grainers you need a 1 in 8 twist, a 1 in 7 would b great too this is why i sold my bushy varminter, it was an awesome gun, but i wanted to shoot 77's, and at 100 yards it looked as if i was shooting a shotgun at the target |
And you're complaining? I'm using a 1-8 twist Mike Rock match barrel in my GAP target rifle. I had George chamber it for the 77grn SMK's, and they absolutely drive tacks with that load. I'm just hoping that the rifle also likes one of the less expensive match loads for informal practice. 
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