Back in January I had started load development using the 180 gr. AccuBond. I tried a few charge weights with R-16 and a few seating depths. I am close to a good load with the 180 AB but haven't found the right bullet jump yet. I have tried from .070" to .100 jumps. I have to go either shorter or longer but am not sure which way.
Meanwhile I wanted to shoot some new brass just to get some once fired cases. So, since I had a box of 180 Partitions sitting around, I loaded some of those with a couple of different powders with a .020" bullet jump and shot them. I was pleasantly surprised with the results. Reloder 16 gave very consistent velocities. So, I adjusted my load to compensate for fired brass instead of new brass and loaded up four groups of cartridges with bullet jumps of .020", .030", .040", and .050".
The results are shown below. The first target shows groups with .020" and .030" bullet jumps. The second target shows groups with .040" and .050" bullet jumps. The group with the .020" bullet jump replicates the target I had with the new brass.
As you can see from the targets:
- With bullet jumps of .020” and .030” I had three bullets “in” and one bullet “out”.
- With a bullet jump of .040”, I had a four shot group of .66”
- With a bullet jump of .050”, I had a four shot group just at 1” but with a horizontal string.
Also note worthy is how consistent the velocities are with this powder. With any one bullet jump, the maximum velocity spread was 13 fps. Across all 16 shots with 4 different bullet jumps, the extreme velocity spread was only 19 fps.
The load with the .040" jump is the best combination I have found so far with a 180 gr. bullet.
The only published load data I have found is on the Alliant Powder website. According to the Alliant Powder website, their max load with the 180 Partition and R-16 is 64.1 gr with a velocity of 3013 fps. QuickLOAD, with all the variables adjusted to match my results, indicates a maximum pressure of about 60,200 psi. So, I think I am safe from a pressure stand point. At 2936 fps I am 95 fps faster than the Nosler factory load with the 180 AccuBond (as shot in my rifle).
So, my question is "Where do I go from here"?
Obviously, I need to retest at .040" jump. If it repeats, is that as good as it is going to get with this combination of bullet and powder?
Should I try a range with .040", .045", and .050"? Should I try a jump of .060" I don't want to burn up powder and bullets just to see what happens...
I do have other bullets and powders to try once I have 180 Partition and R-16 combination nailed down.
Dan
Meanwhile I wanted to shoot some new brass just to get some once fired cases. So, since I had a box of 180 Partitions sitting around, I loaded some of those with a couple of different powders with a .020" bullet jump and shot them. I was pleasantly surprised with the results. Reloder 16 gave very consistent velocities. So, I adjusted my load to compensate for fired brass instead of new brass and loaded up four groups of cartridges with bullet jumps of .020", .030", .040", and .050".
The results are shown below. The first target shows groups with .020" and .030" bullet jumps. The second target shows groups with .040" and .050" bullet jumps. The group with the .020" bullet jump replicates the target I had with the new brass.
As you can see from the targets:
- With bullet jumps of .020” and .030” I had three bullets “in” and one bullet “out”.
- With a bullet jump of .040”, I had a four shot group of .66”
- With a bullet jump of .050”, I had a four shot group just at 1” but with a horizontal string.
Also note worthy is how consistent the velocities are with this powder. With any one bullet jump, the maximum velocity spread was 13 fps. Across all 16 shots with 4 different bullet jumps, the extreme velocity spread was only 19 fps.
The load with the .040" jump is the best combination I have found so far with a 180 gr. bullet.
The only published load data I have found is on the Alliant Powder website. According to the Alliant Powder website, their max load with the 180 Partition and R-16 is 64.1 gr with a velocity of 3013 fps. QuickLOAD, with all the variables adjusted to match my results, indicates a maximum pressure of about 60,200 psi. So, I think I am safe from a pressure stand point. At 2936 fps I am 95 fps faster than the Nosler factory load with the 180 AccuBond (as shot in my rifle).
So, my question is "Where do I go from here"?
Obviously, I need to retest at .040" jump. If it repeats, is that as good as it is going to get with this combination of bullet and powder?
Should I try a range with .040", .045", and .050"? Should I try a jump of .060" I don't want to burn up powder and bullets just to see what happens...
I do have other bullets and powders to try once I have 180 Partition and R-16 combination nailed down.
Dan
