I have a Rock River Predator Rursuit 20" that I have been trying to get to group with little success. I have a 12-42 Nightforce BR scope that I transfered from another rifle mounted on it and I know the scope is good and everything is tight.
The barrel is a 1 in 8 and I originally tried 50gr v-max with Benchmark because I have an abundance of both. I wasn't getting consistant groups so I thought the bullets might have been to light to stabilize. I tried a ladder test with 55gr v max and Benchmark and found a load that shot some decent groups averaging 1/2"-3/4" at 100 yards.
Last night I tried that same load at 425 yards and was shooting at a 12" steel plate. I knew what the hold should be which I confirmed with a ballistic calculator. I had a lot of vertical stringing that wasn't showing up at the close range, I even had rounds going under and over the plate.
I am using LC brass that I trimmed but has multiple year headstamps and I am wondering if that could be part of the problem. I am using Federal 205M primers and I have standard CCI small rifle primers I can try also. I am looking for advice on what I should try next and any help would be appreciated. I wouldn't think 55gr bullets would be too light to stabilize in a 8 twist but maybe I need to try heavier bullets also.
The barrel is a 1 in 8 and I originally tried 50gr v-max with Benchmark because I have an abundance of both. I wasn't getting consistant groups so I thought the bullets might have been to light to stabilize. I tried a ladder test with 55gr v max and Benchmark and found a load that shot some decent groups averaging 1/2"-3/4" at 100 yards.
Last night I tried that same load at 425 yards and was shooting at a 12" steel plate. I knew what the hold should be which I confirmed with a ballistic calculator. I had a lot of vertical stringing that wasn't showing up at the close range, I even had rounds going under and over the plate.
I am using LC brass that I trimmed but has multiple year headstamps and I am wondering if that could be part of the problem. I am using Federal 205M primers and I have standard CCI small rifle primers I can try also. I am looking for advice on what I should try next and any help would be appreciated. I wouldn't think 55gr bullets would be too light to stabilize in a 8 twist but maybe I need to try heavier bullets also.