I loaded some of the Hornady 350 gr. Interlock FP bullets in the 450 Marlin. I worked my charge weights up to 48.5 grs. of H4198 which, according to the Hodgden info and Quickload info, would be the max load for pressures of 43,500 psi.
I shot the following targets at 100 yards and 200 yards. My average velocity for the nine shots was 2049 fps. The last time I shot the factory loads with the 350 gr. FP I measured 2054 fps with a sample size of three shots. Previously, I had measured factory loads at 2019 fps with a sample size of three shots. So, I appear to have duplicated the 350FP factory loads (which are no longer available) for average velocity.
I was fairly happy with the 100 yard target. The grids are one inch square. The center white bulls-eye is 2" in dia.
However, the 200 yard target was less satisfying. But the aiming dot in the reticule covers over 3" of the target. It looks like it covers about 4" of target. So, my aiming was somewhat compromised. Maybe with a better or different reticule I could tighten the group size. I will experiment with different targets to try to improve the aiming.
My main concern is the velocity variation with an ES of 41 fps. You can easily see the impacts points on the 200 yard target seem to correspond to muzzle velocity. The higher impact points had higher muzzle velocities. Maybe it is just a fluke in the data but I observed this variation of impact elevation with velocity repeatedly with this rifle.
Is this amount of velocity variation reasonable with this type of cartridge? What factors affect the velocity variation in this type of cartridge? Is there anything I can do to reduce the velocity variation?
I shot the following targets at 100 yards and 200 yards. My average velocity for the nine shots was 2049 fps. The last time I shot the factory loads with the 350 gr. FP I measured 2054 fps with a sample size of three shots. Previously, I had measured factory loads at 2019 fps with a sample size of three shots. So, I appear to have duplicated the 350FP factory loads (which are no longer available) for average velocity.
I was fairly happy with the 100 yard target. The grids are one inch square. The center white bulls-eye is 2" in dia.
However, the 200 yard target was less satisfying. But the aiming dot in the reticule covers over 3" of the target. It looks like it covers about 4" of target. So, my aiming was somewhat compromised. Maybe with a better or different reticule I could tighten the group size. I will experiment with different targets to try to improve the aiming.
My main concern is the velocity variation with an ES of 41 fps. You can easily see the impacts points on the 200 yard target seem to correspond to muzzle velocity. The higher impact points had higher muzzle velocities. Maybe it is just a fluke in the data but I observed this variation of impact elevation with velocity repeatedly with this rifle.
Is this amount of velocity variation reasonable with this type of cartridge? What factors affect the velocity variation in this type of cartridge? Is there anything I can do to reduce the velocity variation?
