Trip report: Redding Comp Pro v. Lee dies, and magnum v. standard prim

[cwsanfor]

This eight rung test of 10 mm used one powder, load, bullet, OAL, etc., varying (1) combinations of Lee dies and Redding Competition Pro dies, and (2) magnum and standard primers in these combinations:

1. Lee size, seat, crimp; Standard primers
   
2. Lee size, seat, crimp; Magnum primers
   
3. Redding seat, Lee size, FCD; Standard primers
   
4. Redding seat, Lee size, FCD; Magnum primers
   
5. Redding size, seat, Lee FCD; Standard primers
   
6. Redding size, seat, Lee FCD; Magnum primers
   
7. Redding size, seat, crimp; Standard primers
   
8. Redding size, seat, crimp; Magnum primers
   

All loads were 13.6 gr Accurate Arms #9 (weighed on a just-calibrated RCBS Chargemaster) under Precision Delta 180 gr FMJ assembled on a Hornady LNL AP with 1.26 COL in virgin Starline brass, load temperature 45F (actually shot at 50-55F) from a stock Glock G20sf except for the Bar-Sto barrel and 20# ISMI recoil springs. Predicted values are from QuickLoad v.3.6.

VELOCITY

it appears that magnum primers in this load increase velocity about 26 fps: that is, the AA #9 velocity was less than predicted by an average 80 fps with standard primer, and brought closer to predicted with magnum primers at an average delta of 54 fps.

STANDARD DEVIATION OF VELOCITY

I'm not sure how statistically sound simply averaging summed standard deviations is (I'll ask the statistician, a former Navy Surface to Air Warfare Officer, Monday), but magnum primers reduce SD from 10.8 to 9.2, or 1.6.

GROUPS

The magnum primers tightened groups a bit. This is pretty subjective (because I am a mediocre shot and shooting through the chrono distracts me), but the groups from magnum primers were definitely slightly better, and if I get a Ransom Rest or a better shooter at a greater distance to the target, I am pretty sure I would verify that magnum wins here.

LEE VERSUS REDDING

I think this is scant data to make a call, but it is interesting that the lowest single SD (5.9) and the lowest pair (5.9 + 8.9 = 14.8) is with the Redding Competition Pro seating die and the FCD. I really have seen very little COL drift with eather seating die, so I'd hazard a guess that <if> this is a significant difference, the FCD accounts for it.

CONCLUSION

I will probably try this again with another powder, but I am on the basis of this dataset going to agree with McNett that magnum is the default primer for denser propellants and greater bullet weights in 10mm, and I believe I will continue with the Redding Competition Pro seating die and the FCD until I see a reason to do otherwise.

[superdude]

This eight rung test of 10 mm used one powder, load, bullet, OAL, etc., varying (1) combinations of Lee dies and Redding Competition Pro dies, and (2) magnum and standard primers in these combinations:

1. Lee size, seat, crimp; Standard primers
   
2. Lee size, seat, crimp; Magnum primers
   
3. Redding seat, Lee size, FCD; Standard primers
   
4. Redding seat, Lee size, FCD; Magnum primers
   
5. Redding size, seat, Lee FCD; Standard primers
   
6. Redding size, seat, Lee FCD; Magnum primers
   
7. Redding size, seat, crimp; Standard primers
   
8. Redding size, seat, crimp; Magnum primers
   

All loads were 13.6 gr Accurate Arms #9 (weighed on a just-calibrated RCBS Chargemaster) under Precision Delta 180 gr FMJ assembled on a Hornady LNL AP with 1.26 COL in virgin Starline brass, load temperature 45F (actually shot at 50-55F) from a stock Glock G20sf except for the Bar-Sto barrel and 20# ISMI recoil springs. Predicted values are from QuickLoad v.3.6.

VELOCITY

it appears that magnum primers in this load increase velocity about 26 fps: that is, the AA #9 velocity was less than predicted by an average 80 fps with standard primer, and brought closer to predicted with magnum primers at an average delta of 54 fps.

STANDARD DEVIATION OF VELOCITY

I'm not sure how statistically sound simply averaging summed standard deviations is (I'll ask the statistician, a former Navy Surface to Air Warfare Officer, Monday), but magnum primers reduce SD from 10.8 to 9.2, or 1.6. i don't think it is. i'm not sure what your design is, but the usual way to compare numbers is to compare their average, based on their respective standard deviations. adding them together and just comparing the means loses the SD of those values. without that your comparing the means isn't necessarily useful.

GROUPS

The magnum primers tightened groups a bit. This is pretty subjective (because I am a mediocre shot and shooting through the chrono distracts me), but the groups from magnum primers were definitely slightly better, and if I get a Ransom Rest or a better shooter at a greater distance to the target, I am pretty sure I would verify that magnum wins here. yeah, a Ransom Rest is the better way to go. it's important to eliminate the human factor, and you've already admitted that you were distracted, so a more objective test is required. depending on how you've conducted your test you could run a statical comparison of the group sizes.

LEE VERSUS REDDING

I think this is scant data to make a call, but it is interesting that the lowest single SD (5.9) and the lowest pair (5.9 + 8.9 = 14.8) is with the Redding Competition Pro seating die and the FCD. I really have seen very little COL drift with eather seating die, so I'd hazard a guess that <if> this is a significant difference, the FCD accounts for it.

CONCLUSION

I will probably try this again with another powder, but I am on the basis of this dataset going to agree with McNett that magnum is the default primer for denser propellants and greater bullet weights in 10mm, and I believe I will continue with the Redding Competition Pro seating die and the FCD until I see a reason to do otherwise.

your experimental design is complicated because you have multiple variables. it sounds like a good attempt to run a controlled experiment but there is some missing information, such as sample size, how many groups you fired, how many rounds per group and so on. the accuracy component would also require you to know the accuracy potential of the bullet/powder combination you're using. for example, if that bullet is normally as accurate as a laser beam in your gun with a variety of powders and you see a 6 inch difference in your comparison then you're okay. but if that bullet happens to shoot like crap and you find a 1/2 inch difference, well that could be random noise. i'm not familiar with the Quickload software but there is always a concern with any predetermined calculations and comparing velocity from a computer output to the real velocity of a barrel is not very meaningful because every barrel is different and matching or not matching the computer output doesn't mean anything except that it didn't match the computer output. the only velocity that matters is the comparison between the two primers and even those values need to be compared statistically to determine if they are the same or different.

after all that, it's fun to run experiments on this stuff. but lordy it takes time and money!