I had my 243 BAR out the other day trying out some loads. I used the same bullets, the same primers, the same cases, and the same OAL but tried several different powders. There were dramatic differences between powders. I would have to check my records to see which powders it did like but know it did not like IMR 4064 and IMR 4350. I had the same results with 100 grain Hornady pointed soft point and Barnes 85 grain TSX.
I wonder whether the original owner got rid of the rifle because he/she could not get it to shoot right. I have had several rifles that evidently were put on the market for that reason. I had to try a bunch of loads for a Ruger #1 in 7/57 before I got one it liked. My elk rifle, a M70 338 WM, took a good bit of work to undo several things the previous owner had done to try to get it to shoot right. It shoots a whole lot better than I do now. I traded off a M70 in 270 WSM to a friend who traded it off for something else. A M70 in 7mm WSM is still in the tinkering stages but was sold by the first owner because he could not get it as consistent as he demanded for long range shooting. A M700 in 223 that I bought new would not shoot some bullets worth a hoot. I finally found a load it shoots very well.
I wonder whether the original owner got rid of the rifle because he/she could not get it to shoot right. I have had several rifles that evidently were put on the market for that reason. I had to try a bunch of loads for a Ruger #1 in 7/57 before I got one it liked. My elk rifle, a M70 338 WM, took a good bit of work to undo several things the previous owner had done to try to get it to shoot right. It shoots a whole lot better than I do now. I traded off a M70 in 270 WSM to a friend who traded it off for something else. A M70 in 7mm WSM is still in the tinkering stages but was sold by the first owner because he could not get it as consistent as he demanded for long range shooting. A M700 in 223 that I bought new would not shoot some bullets worth a hoot. I finally found a load it shoots very well.