My son Stacy and I did some 223 load development for the AR 223 Match Rifle AKA the Space Gun. The application is for loads for the AR match rifle for shooting the NRA National Match Course. We documented the research in a report which is rather rigorous and included the firing of 114 ten shot groups with four bullets and 19 powders. Additional groups were fired to obtain velocity data. We were looking for the best combination of group size and velocity. The Executive summary for the report is copied below. The complete report is too large to attach but if you would like to have a copy email me at chkunz@bellsouth.net and I will send you a copy.
Executive Summary
What is the highest velocity load that one can develop in .223 Remington, that also possesses the best accuracy from an AR15 Match Rifle platform with a 1:8 twist, 26 inch length barrel and JGS “Wylde†chamber; meeting the target (“X-ringâ€) and operational requirements of NRA Highpower National Match Course (NMC) competition?
Answering this question with a high-degree of confidence requires an arduous application of the scientific method in order to produce an answer of statistically meaningful value –the primary goal of this report. The short answer to this question is 23.8gr of Alliant’s Reloader® (RE) 15 powder behind a 75gr Hornady BTHP bullet with a cartridge over-all-length (OAL) of 2.256in (a.k.a. “mag lengthâ€) for the “short†(200 & 300yds) ranges and 23.9gr of Accurate’s (MR) 2520 powder behind a 75gr Hornady A-Maxâ„¢ bullet seated 0.015in off the lands for the “mid†(600yd) range. In addition to this basic answer, many other aspects significant to reloading for this requirement are supported by the following report:
ï‚· Total rounds expended throughout these tests: 1760. 114 10-shot groups were fired for accuracy. 4 different bullets and 19 different powders were tested. An estimated 400 hours was expended in support of these tests.
 Accuracy Budget – How accurate does the load need to be to satisfy the target requirements (“X†ring dimensions) of NRA Highpower competition? One should not accept a load for application toward NRA Highpower competition with a 20-shot Mean Radius (MR) at 100 yards greater than 0.35in for the “short†range application and 0.32in for the “mid†range application. Any load that produces MR results, at 100yds, less than this should be considered highly advantageous. [See Part III for explanation w/regard to this claim.]
 Velocity – How fast is fast? 19 different powders were initially evaluated toward answering this question. Powders which routinely produced exceptionally high velocities and accurate loads behind 77gr SMKs, 75gr HDY BTHPs (2850-2900fps range), 80gr SMKs and 75gr HDY A-Max™ (2750-2850fps range) bullets were H4895, N540, N140, MR-2520, and RE-15. For the “Short†and “Mid-Range†loads identified above, as most accurate, the average muzzle velocities are 2862fps and 2887fps, respectively. [See Part I and Annex A]
 Load Comparison – A scoring system was established within the report to objectively compare one load vs. another based on accuracy and velocity; ranking all loads from best (high velocity/small group size) to worst with a non-dimensional number. The loads recommended above were based on this evaluation [See Part V and Annex C].
 Scientific Method – ALL measured data is included within this report and utilized within all evaluations –“cherry picking†the best data was not considered and no shots were omitted. A logical and rigorous process was applied toward a sequential progression from one testing phase to another in order to produce statistically meaningful results. In all cases, 10-shot groups were fired and, in many cases, repeatedly, in order to gain average results based on 20 or, where possible, 30 shots; increasing the statistical confidence levels in all regards.
 Mean Radius – The Mean Radius method was employed within this research as the most effective process by which to measure group size(s); effectively “weighing†all shots within a group equally. i.e. vs. the Extreme Spread method which only values the two worst shots of a group equally.
The most significant discovery gained, as a result of this load development process, was the fact that the .223 Remington cartridge, when fired in an AR15 Match Rifle, possessed the bench-rest accuracy potential to effectively double the size of the NRA NMC “X-ring†dimension (relatively speaking). This level of accuracy will enable a Master class competitor in NRA High Power Rifle competition to have the potential of “X-ring†performance; humbling us all in our ability to hold as well as our rifles and ammunition will shoot. However, only with the most accurate handloads can this advantage be realized –the purpose of this report’s research. I hope you find this information useful toward your own reloading and competitive endeavors.
Enjoy, and, as always, be safe in all your reloading practices.
Executive Summary
What is the highest velocity load that one can develop in .223 Remington, that also possesses the best accuracy from an AR15 Match Rifle platform with a 1:8 twist, 26 inch length barrel and JGS “Wylde†chamber; meeting the target (“X-ringâ€) and operational requirements of NRA Highpower National Match Course (NMC) competition?
Answering this question with a high-degree of confidence requires an arduous application of the scientific method in order to produce an answer of statistically meaningful value –the primary goal of this report. The short answer to this question is 23.8gr of Alliant’s Reloader® (RE) 15 powder behind a 75gr Hornady BTHP bullet with a cartridge over-all-length (OAL) of 2.256in (a.k.a. “mag lengthâ€) for the “short†(200 & 300yds) ranges and 23.9gr of Accurate’s (MR) 2520 powder behind a 75gr Hornady A-Maxâ„¢ bullet seated 0.015in off the lands for the “mid†(600yd) range. In addition to this basic answer, many other aspects significant to reloading for this requirement are supported by the following report:
ï‚· Total rounds expended throughout these tests: 1760. 114 10-shot groups were fired for accuracy. 4 different bullets and 19 different powders were tested. An estimated 400 hours was expended in support of these tests.
 Accuracy Budget – How accurate does the load need to be to satisfy the target requirements (“X†ring dimensions) of NRA Highpower competition? One should not accept a load for application toward NRA Highpower competition with a 20-shot Mean Radius (MR) at 100 yards greater than 0.35in for the “short†range application and 0.32in for the “mid†range application. Any load that produces MR results, at 100yds, less than this should be considered highly advantageous. [See Part III for explanation w/regard to this claim.]
 Velocity – How fast is fast? 19 different powders were initially evaluated toward answering this question. Powders which routinely produced exceptionally high velocities and accurate loads behind 77gr SMKs, 75gr HDY BTHPs (2850-2900fps range), 80gr SMKs and 75gr HDY A-Max™ (2750-2850fps range) bullets were H4895, N540, N140, MR-2520, and RE-15. For the “Short†and “Mid-Range†loads identified above, as most accurate, the average muzzle velocities are 2862fps and 2887fps, respectively. [See Part I and Annex A]
 Load Comparison – A scoring system was established within the report to objectively compare one load vs. another based on accuracy and velocity; ranking all loads from best (high velocity/small group size) to worst with a non-dimensional number. The loads recommended above were based on this evaluation [See Part V and Annex C].
 Scientific Method – ALL measured data is included within this report and utilized within all evaluations –“cherry picking†the best data was not considered and no shots were omitted. A logical and rigorous process was applied toward a sequential progression from one testing phase to another in order to produce statistically meaningful results. In all cases, 10-shot groups were fired and, in many cases, repeatedly, in order to gain average results based on 20 or, where possible, 30 shots; increasing the statistical confidence levels in all regards.
 Mean Radius – The Mean Radius method was employed within this research as the most effective process by which to measure group size(s); effectively “weighing†all shots within a group equally. i.e. vs. the Extreme Spread method which only values the two worst shots of a group equally.
The most significant discovery gained, as a result of this load development process, was the fact that the .223 Remington cartridge, when fired in an AR15 Match Rifle, possessed the bench-rest accuracy potential to effectively double the size of the NRA NMC “X-ring†dimension (relatively speaking). This level of accuracy will enable a Master class competitor in NRA High Power Rifle competition to have the potential of “X-ring†performance; humbling us all in our ability to hold as well as our rifles and ammunition will shoot. However, only with the most accurate handloads can this advantage be realized –the purpose of this report’s research. I hope you find this information useful toward your own reloading and competitive endeavors.
Enjoy, and, as always, be safe in all your reloading practices.
