I charged these in 11-round sets


with each tested propellant. I used a Hornady Lock-N-Load measure to drop all charges. I used properly moly-plated


Barnes Varmint Grenade bullets. I seated those using the RCBS Gold Medal seating die at an overall length of 1.78-inches (20/1000-inch bullet-to-rifling jump in this CZ 527). I chronographed all shots using


the Oehler 35P using sufficient screen spacing to give much better than 1-fps resolution. Ten shots with each combi- nation gives a reasonable degree of sta- tistical validity but twenty shots would have been better — just not feasible. I fired all loads using Power Pro


300-MP, then all loads using IMR 4227 (C), then all loads using H110, then all loads using Lil’ Gun. I cleaned the bore before beginning each propellant test series and I fired one fouler with each primer type before recording velocity and accuracy for the remaining ten shots of each type. My goal was to minimize fouling-related variations. The ceramic treated bore and moly-plated bullets kept bore fouling to a degree that was (most likely) insignificant during each test series. All tests included one fouler shot


and ten shots for velocity and accuracy. I would have included the Remington 5½ if I could have found any! Other than that, this list includes all readily available primers that might possibly be appropriate for the Hornet. (While I would have preferred to fire 20-shot strings, that would have required firing almost 1,000 shots, which was beyond what I felt was feasible. As is, these data alone represent many hours of loading and three days at the range.) Any conclusions that we might


draw from these results could well be seriously flawed. Before touching upon some “obvious” points that might well fall into the “erroneous” category, I want to state the bottom line on any discussion of primer substitutions, which represent a serious truth that all handloaders should come to embrace: It is fundamentally impossible to predict with any level of certainty the precise consequences of any primer substitution in any load.


Laboratory testing with perfectly


normal loads in conventional cartridges, such as the 308 Winchester, have proven


that any primer substitution, whether to a milder, hotter, or supposedly similar primer, can result in pressure increase, decrease, or no difference. Similarly, the same substitution can result in velocity increase, decrease, or no difference. The problem is, correlation between these changes does not always exist! Some- times, any particular primer change can result in higher pressure and less veloc- ity or vice versa. Any result is possible


and ballisticians have observed results that most shooters would not believe. For example, substitution of a standard pistol primer for a magnum pistol primer doubling chamber pressure. With regard to primer choice and


velocity, 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


www.varminthunter.org Page 115


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