Just for fun I thought I would post an email that I sent to my Dad and a hunting buddy yesterday. We are all going to be deer hunting with Marlin 45/70’s this fall, in grizzly country. I’m trying to find the right balance of accuracy and power. Feel free to add your two cents!
I put my 20 test rounds down range and came up with some frustrating data. What I have so far is not good enough. I will need to run another test batch
Parameters:
Marlin 1895GS with 3X Leupold.
No sight adjustments were made.
I used a Lead Sled shooting rest, loaded up with 60 pounds of weight. Recoil was not a factor.
All shots were done at 100 yards.
The barrel was reasonably cool at all times, only slightly warm to the touch.
I shot 4 rounds at each powder charge.
I started with 42 grains and worked my way up.
All loads were done with IMR 4198 and a Magnum rifle primer.
None of the casings showed significant pressure signs. At the higher end loads, the primers started to show a touch of pressure signs.
Leadhead bullets, 425 gr. WFNGC.
Results:
42 grains:
4 shot spread (the two widest points) = 3.29
3 shot widest point = 1.55
2 shot (closest - smallest distance between any 2 rounds) = 0.96
Average = 1.93
43 grains:
4 shot = 2.80
3 shot = 2.21
2 shot = 0.39 (but these two rounds were about 2 inches right of the other 2 rounds!)
Average = 1.80
44 grains:
4 shot = 2.60
3 shot = 2.44
2 shot = 0.63
Average = 1.89
45 grains:
4 shot = 3.82
3 shot = 2.88
2 shot = 1.29
Average = 2.66
46 Grains:
Two shots completely off target, I think they missed high.
Two shots on target were 2.10 spread.
Conclusion:
I think I found the limit of how hard we can push this bullet. I am amazed at the difference one or two grains of powder can make in accuracy. The 45 and 46 grain loads, which should be about 1900 fps were worthless. The 43 and 44 grain loads which should be about 1600 to 1700 fps were the most accurate. I should note that the very first shot at 42 grains was several inches lower than the remaining 3. This skewed the data significantly. First shot out of a cold barrel? A little to much Hoppes left in the bore? I pulled the first shot? Who knows. The data seems to show that less powder is better. Of course I don't want to down load this thing to much and negate the power that the rifle is capable of, so I need to find the sweet spot.
I am thinking of loading up another 20 test rounds, starting at 40 grains. 4 rounds each at 40, 41, 42, 43 and 44 grains.
Do you think that the Magnum primer could be causing any problems? I don't want to introduce to many variables, but I could switch to a standard primer. IMR 4198 is a mid to slow burning powder. Could the Magnum primer ignite the powder to fast? I don't know, I'm reaching here, but I think the gun should be capable of a lot better. Unless you guys convince me otherwise, I think I will stay with the Magnum primer, for consistency, on the next 20 test rounds.
In closing, the average spread does not seem to bad on the 42, 43, and 44 grain loads mathematically, but if you were to see the targets, you would be as frustrated as I am. There was ample spread and what I would usually call a flyer on each target. Put in perspective, these loads may not be capable of a head shot at 100 yards. If you got that "flyer" on that particular trigger squeeze you may very well miss. That is just not good enough for me, I know this gun can do better.
Suggestions / comments / analysis?
