Okay, so here we go. A couple nights of partying delayed me a couple of days. I am, for the record, totally stealing Wobbly's report for a template.
Environmental Conditions -- It's Florida, so temperature was hot, and the air was saturated with water.
(Powder, primers, and brass were the same for all 4 bullets tested)
Powder: IMR 7625
Primers: CCI 500
Brass: Starline virgins
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The Loads:
Bullet #1 124gr Berry's Hollow Back Round Nose Thick-plated Double Struck (why didn't they go with a long name?)
Load data was taken from the Hodgdon online load database. I could not find exactly what I needed, but the Hodgdon database did have 130 grain Berry's RN loaded at OAL 1.15, which was almost .02 under what those bullets push test to in my barrel, so I used that, starting at the bottom of that data, reasoning that with the same powder and OAL but with a lighter bullet of the same basic design and manufacture, I would be starting in a safe range.
The results from the ProChrono:
4.2gr 941fps avg ES-28
4.3gr 972fps avg ES-57
4.4gr 999fps avg ES-29
4.5gr 992fps avg ES-21
4.6gr 1022fps avg ES-15
4.7gr 1059fps avg ES-20
Between the 4.4 and 4.5 strings, I began to suspect that a cloudless sky, direct sunlight, and shiny Berry's bullets were messing with the chrono. I used cardboard to block direct sunlight from the side, and things settled down. I suspect that is the reason for the drop in extreme spreads. And I suspect that the results of the first three strings are high.
Bullet #2: 124 Montana Gold JHP
Again I had a little trouble finding a precise load to draw from. These bullets push test to 1.089 in my barrel, and I didn't feel comfortable going longer than 1.079. Sierra's fifth edition has load data for 125 jhp at 1.075, indicating safe charges between 4.5 and 5.4 grains. After noting some load discrepancies between Hodgdon and Sierra with another bullet and the 7625, a discrepancy in which Hodgdon was the more conservative of the two, I decided to drop Sierra's starting charge down to 4.2, and I went with the slightly higher OAL of 1.079.
The results from the ProChrono:
4.2gr LOST -- Hit the wrong button
4.3gr 1027fps avg ES-16
4.4gr 1046fps avg ES-21
4.5gr 1056fps avg ES-22
If you want to use MG 124JHP with this powder, at a similar OAL, I would recommend starting a bit lower than I did. Everything went fine, but I believe a bigger cushion would be prudent. I am going do a second round of these and start lower so that I have a longer list of charges to compare to accuracy bumps attained from those charges to better see what's going on. I will post here again when I do.
Bullet #3: 125 BBI Round Nose -- Moly-coated
Bullet #4: 147 BBI Flat Point -- Moly-coated
I mention these two here because I did test them and planned on including them, BUT I have chosen not to include the data. There wasn't anything particularly close to draw from with my OAl. I really had to do a lot of extrapolation from published loads and from other shooter's loads to find a starting range I felt was safe, and I don't feel comfortable posting it where others might take it for science and use it. I will say that both bullets produced sufficiently accurate loads; however, while extreme spreads and standard deviations were acceptable, they were a little higher than the other two bullets. I also had greater variation in actual loaded OAL with these two bullets, so that might be a contributing factor.
SHOOTING EXPERIENCE:
Feel -- I have a lifetime of shooting paying more or less no attention to how one powder feels vs another. I pay attention now, but I lack a variety of experiences in the short time I have been paying attention, so a meaningful assessment of feel is impossible. At every velocity with every bullet I shot, it was pleasant to shoot. That's about as specific as I can get.
Accuracy -- I didn't measure groups, but I did run new targets for every string, and everything was decent. There were no instances where bumping up to the next tenth of a grain cut group sizes significantly. It was the same for
all four bullets I tested with the 7625: within the loads for a particular bullet, accuracy was boringly consistent from one charge to the next. And while the loads with the Montana Gold were a bit tighter than the other three, I strongly suspect that that credit goes to the MG bullet on its own, not some particular affinity between 7625 and the MG's.
That's it. Feel free to chastise me at will. Thank you for playing along.
