Aguila Blanca
Staff
Special warning notice
CAUTION: The following post includes loading data that the powder manufacturer data indicates will be 14% above +P pressure. It may not be that high in YOUR gun, but you USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assumes any liability for any damage or injury resulting from the use of this information.
Has anyone been using Gordon's Reloading Tool?
Two recent/current threads dealing with seating depth and pressure led me to download a fresh copy of GRT and take a look at it to see if might be a decent predictor of pressures. It has calculations for it -- the question is how accurate they are. GRT now includes Hodgdon HP-38 (which is the same as Winchester 231), and that's my powder, so I can compare to real world results.
And what I got on a trial run was not even remotely related to what I found in the real world, and what Shooting Times found in the real world.
For perspective, a couple of years ago I realized that EVERYONE at the club where I hoped (before my hip went bad) to be shooting IDPA was shooting 9mm. My play guns (and my carry guns) are 1911s, in .45 ACP. So I set out to come up with a .45 ACP load that's equivalent to 9mm. And Shooting Times had the answer -- a friend sent me a link to an article of recoil vs. bullet weight. The author conveniently used two Berry's bullets (the same two that I have), and Winchester 231 powder. And one of his loads was 5.3 grains, which happens to be what I get from one aperture on my Lee AutoDisk powder measure. The author loaded to 1.24" C.O.L. and I load to 1.25" -- not a huge difference.
So I have reported, real world velocities for both bullets, over 5.3, 5.7, and 6.1 grains of the same powder.
Then I ran those same loads through GRT (except that I neglected to change the C.O.L. from 1.26" to 1.24"). The results were a shock, especially considering that the discrepancies would be been worse if I had used the correct C.O.L.
For the 230-grain bullet, Shooting times reported velocities of 724 fps for 5.3 grains, 783 fops for 5.7 grains, and 869 fps for 6.1 grains. That velocity for 5.3 grains is not far from my chrono results. BUT ... GRT came up with 863 fps, 900 fps, and 935 fps, respectively. And GRT reported that the first two were near max pressure and the third was over-pressure.
For the 185-grain bullet, Shooting Times reported velocities of 687 fps, 762 fps, and 812 fps. GRT calculated 942 fps, 984 fps, and 1024 fps.
Consequently, I'd like to know if anyone else has used GRT and had real-world numbers to use for a comparison. I didn't expect the calculated results to be exact to three decimal places, but these numbers are off by a factor of 15% to 37%. The average for the six samples was 22.33%. Am I being naive in thinking it should come closer than that?
CAUTION: The following post includes loading data that the powder manufacturer data indicates will be 14% above +P pressure. It may not be that high in YOUR gun, but you USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assumes any liability for any damage or injury resulting from the use of this information.
Has anyone been using Gordon's Reloading Tool?
Two recent/current threads dealing with seating depth and pressure led me to download a fresh copy of GRT and take a look at it to see if might be a decent predictor of pressures. It has calculations for it -- the question is how accurate they are. GRT now includes Hodgdon HP-38 (which is the same as Winchester 231), and that's my powder, so I can compare to real world results.
And what I got on a trial run was not even remotely related to what I found in the real world, and what Shooting Times found in the real world.
For perspective, a couple of years ago I realized that EVERYONE at the club where I hoped (before my hip went bad) to be shooting IDPA was shooting 9mm. My play guns (and my carry guns) are 1911s, in .45 ACP. So I set out to come up with a .45 ACP load that's equivalent to 9mm. And Shooting Times had the answer -- a friend sent me a link to an article of recoil vs. bullet weight. The author conveniently used two Berry's bullets (the same two that I have), and Winchester 231 powder. And one of his loads was 5.3 grains, which happens to be what I get from one aperture on my Lee AutoDisk powder measure. The author loaded to 1.24" C.O.L. and I load to 1.25" -- not a huge difference.
So I have reported, real world velocities for both bullets, over 5.3, 5.7, and 6.1 grains of the same powder.
Then I ran those same loads through GRT (except that I neglected to change the C.O.L. from 1.26" to 1.24"). The results were a shock, especially considering that the discrepancies would be been worse if I had used the correct C.O.L.
For the 230-grain bullet, Shooting times reported velocities of 724 fps for 5.3 grains, 783 fops for 5.7 grains, and 869 fps for 6.1 grains. That velocity for 5.3 grains is not far from my chrono results. BUT ... GRT came up with 863 fps, 900 fps, and 935 fps, respectively. And GRT reported that the first two were near max pressure and the third was over-pressure.
For the 185-grain bullet, Shooting Times reported velocities of 687 fps, 762 fps, and 812 fps. GRT calculated 942 fps, 984 fps, and 1024 fps.
Consequently, I'd like to know if anyone else has used GRT and had real-world numbers to use for a comparison. I didn't expect the calculated results to be exact to three decimal places, but these numbers are off by a factor of 15% to 37%. The average for the six samples was 22.33%. Am I being naive in thinking it should come closer than that?