cases) H110 and IMR 4227 might be least sensitive. But, almost certainly, what the data of this test actually suggest is that I just happened to have chosen charges of these two propellants that generate barrel times at or near an accuracy sweet spot for this gun. Had I tested, perhaps, half-grain less with each propellant, I might have seen a reversal of these relative-accuracy results. In one important way, Alliant


This target, with four groups, is reasonably representative of the 88 groups fi red for this study. Note that group marked 66 includes only four shots. I had over-adjusted the scope and the fi rst shot missed the paper (this happened twice), which led to my complete loss of concentration and a blown group.


velocity uniformity, again this analysis suggests that Lil’ Gun is (by far) most sensitive and H110, 300-MP, and 4227 are all similarly sensitive. With regard to primer choice and


accuracy, while I hesitate to entertain the concept that these data might have any value, this analysis suggests that with the charge tested (a full case in fi red and neck-sized 45-grain Remington


Power Pro 300-MP was relatively insen- sitive to primer choice — nothing tested gave what I would call decent ballistic uniformity. This does not mean that this propellant is hopeless for the Hornet; this merely suggests that fi nding an ac- curate load will be more diffi cult. Ideas include heavier bullets, or a swirled charge with this bullet (which will allow at least 15.5 grains charge), which is apt to result in signifi cantly better ballistic uniformity). An interesting aside is something


that I have noted before when analyzing data from this sort of study, in far more instances than could reasonably have happened by chance: The fi rst shot fi red after changing primers was either faster or slower than any of the remaining ten shots. Moreover, in none of these tested loads did that fi rst shot fall anywhere near the mean velocity. This simply cannot be a statistical anomaly. I can see two possible explanations


for this. First, primers leave residues in the barrel that alter bullet-to-bore


friction. Second, primer characteristics infl uence resulting propellant residues. Whatever the cause, a fi rst shot that is either fast or slow occurs far more often than chance would suggest. Often, the shot is so much slower or faster than the average of the remaining shots that it is simply not possible that this is a statisti- cal fl uke — something real is happening. This also occurs when switching among primers of the same brand. Therefore, whenever you change


primers in any testing, it probably would be a good idea to ignore the fi rst shot with the new primer. The WSR matched overall unifor-


mity of the Federal 200 but relatively low WSR velocity suggests increased bullet movement (refer to the follow- ing analysis of IMR 4227 data), which is undesirable. With 300-MP, the Fed-100 looks


most promising for accuracy loads. With Lil’ Gun, the Federal 200 was the single star and I will be testing this combina- tion further. With H110, several primers performed similarly. I will stay with the Federal 100 because I have plenty of those and few others. IMR 4227 was the big surprise.


In terms of ballistic uniformity, it performed very well with standard rifle primers. I can only guess that this refl ects the fact that single-based propellants take longer to ignite than double-based propellants do and that, in any case, these primers always move the bullet. I suspect that with this slower-to-ignite propellant, rifl e primers drove the bullet more uniformly into the rifl ing in this particular gun. With pistol primers, likely the bullet did not move and likely with other tested propellants combustion pressure became suffi cient to keep the bullet moving before it stopped moving from the primer blast, which would reduce uniformity. Plenty of speculation here but a reason must exist and, when we consider that two of the rifl e primers produced the low- est two velocities, the bullet-movement hypothesis is hard to discount. I suspect that a gun with different


This was one of the three best groups. Of course, the last shot opened the group but worse, the fi rst three shots were the three closest. I am not immune to pressure.


Page 116 July — September 2011


bore condition or with a different throat length or leade design might react dif- ferently. Therefore, I will use the Federal 100 primer with this and other extruded propellants.


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