nitesite
Member
A shooting buddy asked me to work up a practice load that duplicates as closely as possible his carry load of CorBon DPX 155-gr 10mm in a Glock 29.
This is a compact pistol with only a 3.78" barrel, so the advertised velocities for most 10mm ammunition is almost always quite a bit higher as measured out of 5"-5.5" barrels.
He provided me with 1000 once fired Federal cases and 1000 brass-jacketed 155 RNFP bullets. I opted to try Accurate Arms #5 powder and CCI 300 primers.
The CorBon DPX load chronographed beautifully. Only a 9.53 SD and 17.21 ES which are really amazing numbers.
Altitude 669' Temp 52-degrees
I began to slowly work up a similar load starting with AA#5 at 9.2 grains. I knew going in that the DPX bullet is quite a bit longer because of its cavernous hollow point. Additionally, the all-copper bullet has less density than a lead core bullet, making it even longer to attain the weight it carries. These factors contribute to less case volume available for propellant, as the DPX bullet base is far deeper inside the case than what I could attain with the bullets he provided me. I fully expected to see significantly lower velocities using his jacketed lead bullets with their solid noses. Perhaps some JHPs would have allowed a deeper seat and raised velocities, but then there might be pressure issues. A real challenge to be sure!
Here are the chronograph results from several different powder charges, which were thrown using the Lyman 1200DPS-II digital powder measure and scale my wife bought me for my birthday. It's a wonderful machine, particularly useful for making just five loads of each powder charge in a very short time.
AA#5 9.2 grains
LO 945.33
HI 987.51
AV 970.39
ES 42.18
SD 15.36
AA#5 9.5 grains (worst ES and SD)
LO 964.61
HI 1037.80
AV 994.75
ES 73.19
SD 33.36
AA#5 9.9 grains
LO 1029.33
HI 1092.40
AV 1055.43
ES 63.07
SD 23.83
AA#5 10.0 grains (MAX load)
LO 1063.98
HI 1099.05
AV 1082.09
ES 35.07
SD 14.73 (lowest SD of all)
Here are the final numbers I chronographed when I reached the maximum load of 10.0 grains of AA#5 seated to 1.250" COL:
Even at maximum load limits, there were no signs of dangerous pressures. My primers looked perfectly normal and there was no distortion of the case sidewalls in the base/web area. No swelling was noted where there is an unsupported area of the chamber, and there were no "Glock Smilies" observed on any of the cases. Every round functioned perfectly in my Glock 29, with no failures of any kind to feed, fire, extract and eject.
If he provides me with some JHPs in the future I will have to back off on the starting charge and see how that affects pressures and velocities.
Since I am within just 56-fps of the CorBon DPX factory ammunition I believe that, on my quest to develop a practice load for my friend, I will stop where I am.
This is a compact pistol with only a 3.78" barrel, so the advertised velocities for most 10mm ammunition is almost always quite a bit higher as measured out of 5"-5.5" barrels.
He provided me with 1000 once fired Federal cases and 1000 brass-jacketed 155 RNFP bullets. I opted to try Accurate Arms #5 powder and CCI 300 primers.
The CorBon DPX load chronographed beautifully. Only a 9.53 SD and 17.21 ES which are really amazing numbers.
Altitude 669' Temp 52-degrees
I began to slowly work up a similar load starting with AA#5 at 9.2 grains. I knew going in that the DPX bullet is quite a bit longer because of its cavernous hollow point. Additionally, the all-copper bullet has less density than a lead core bullet, making it even longer to attain the weight it carries. These factors contribute to less case volume available for propellant, as the DPX bullet base is far deeper inside the case than what I could attain with the bullets he provided me. I fully expected to see significantly lower velocities using his jacketed lead bullets with their solid noses. Perhaps some JHPs would have allowed a deeper seat and raised velocities, but then there might be pressure issues. A real challenge to be sure!
Here are the chronograph results from several different powder charges, which were thrown using the Lyman 1200DPS-II digital powder measure and scale my wife bought me for my birthday. It's a wonderful machine, particularly useful for making just five loads of each powder charge in a very short time.
AA#5 9.2 grains
LO 945.33
HI 987.51
AV 970.39
ES 42.18
SD 15.36
AA#5 9.5 grains (worst ES and SD)
LO 964.61
HI 1037.80
AV 994.75
ES 73.19
SD 33.36
AA#5 9.9 grains
LO 1029.33
HI 1092.40
AV 1055.43
ES 63.07
SD 23.83
AA#5 10.0 grains (MAX load)
LO 1063.98
HI 1099.05
AV 1082.09
ES 35.07
SD 14.73 (lowest SD of all)
Here are the final numbers I chronographed when I reached the maximum load of 10.0 grains of AA#5 seated to 1.250" COL:
Even at maximum load limits, there were no signs of dangerous pressures. My primers looked perfectly normal and there was no distortion of the case sidewalls in the base/web area. No swelling was noted where there is an unsupported area of the chamber, and there were no "Glock Smilies" observed on any of the cases. Every round functioned perfectly in my Glock 29, with no failures of any kind to feed, fire, extract and eject.
If he provides me with some JHPs in the future I will have to back off on the starting charge and see how that affects pressures and velocities.
Since I am within just 56-fps of the CorBon DPX factory ammunition I believe that, on my quest to develop a practice load for my friend, I will stop where I am.
