Went out to the range again today to do some more chrono work on varying types of Blue Bullet 9mm rounds, and also to check the rounds I'm using to calibrate steel. (Calibration rounds were previously Hornady 115 gr JHPs, but I'm out of those now, and the replacements are Xtreme 115 JHPs---which considering the keyholing issues with the 124gr ones, suddenly made me nervous.)
For these tests I'm not expecting my chrono to give perfect readings for velocities, since I don't have a light box and the light levels are SIGNIFICANTLY varying over time. Instead, I'm shooting my Montana Gold rounds (which have chronoed at 134 PF consistently at a minimum of three major matches every year for the past three) and using the numbers there to calibrate. So in general, my procedures include shooting 5 MG rounds, then 5 of whatever I'm testing. Periodically I'll change the order and shoot the testing rounds first, then the MG. I shoot them in sets of five, and perform 3-5 tests of each type of round. (And then when I get home I run all sorts of comparative statistics on everything, from sets-of-5-rounds to all of them together. Within each round type, numbers are solidly consistent.)
In reverse order:
Xtreme 115gr JHP, OAL 1.12, 4.6gr WSF---gives me a PF of 112.8 with a StDev of 2.4. For calibration ammo, that's a little low, so I'll probably bump it up to 4.7 or 4.8 gr of WSF. (More on that in a bit.)
Blue Bullets 125 gr RN, OAL 1.115, 4.6gr WSF---gives me a PF of 131.1 with a StDev of 1.1 which is actually less than the 1.4 that I get from my calibration ammo. While this is actually perfectly fine for competition shooting, it is actually a little lower than I like, particularly because WSF powder is reverse-temperature-sensitive. In other words, when it gets hotter it'll actually
slow down and reduce the power factor, which may get entirely too close to 125 for my comfort. I don't really feel much in the way of difference between 130 and 134 PF in 9mm, so upping the powder back to 4.8 (which was the last chrono test) seems like a good idea to me. At 4.8 I got around a 135 PF, and again with WSF running slower when it warms up, that'll put me about at my normal PF. It'll also mean that I can leave my reloading setup exactly the same between my competition ammo and my calibration ammo---I just switch the bullets I'm using, and everything else stays the same.
....as long as everything is accurate.
Finally got a chance to shoot groups at 30 yards today. (Didn't go beyond that, though. Probably need to shoot at 50, just to check, though I'm not really worried about it.) The Blue Bullets (both the 4.6gr and 4.8gr WSF versions) both gave group sizes that matched how I shoot the Montana Gold (actually, potentially slightly better). In addition, just like the MG rounds they shot slightly (1-1.5 inches or so) high at that distance, which is actually appreciated by me since I can put my front sight right under where I'm aiming at distance, which makes it much easier to keep the windage correct. At 15 yards and in, it shoots straight to point of aim.
Accuracy-wise, the Blue Bullets are doing exactly what I need them to do.
Also shot the 4.6gr WSF version one-handed, both SHO and WHO, with the poorest weakest grip I could, and the rounds still had no issues cycling the gun. No jams or malfunctions, and I tested it that way with rounds that had not passed the case gauge.
...thinking I'm probably going to make about 1000 of the 4.8gr WSF version at 1.115, and shoot them for the next couple of matches, then chrono again when the temperature gets above 50 degrees.
New Calibration ammo: Since these were Xtreme bullets, I was rather worried about having the same accuracy (keyholding!) issues that I'm having with the 124gr rounds. Chrono-wise, like I said, I'll be bumping up the powder to 4.8gr (note: I should have mentioned I'm shooting these out of a G17 instead of a G34---I use a G17 for calibration to keep that velocity lower, and I have an extra G17 in a bag with the calibration ammo I can just hand to someone to check steel if I can't make it) to get that power factor at a solid 115.
Accuracy-wise....they shot perfectly well. No issues at all. 15 yards, shot exactly where they should, nice clean holes, no keyholing or anything even remotely similar. Maybe I should have bought 124gr JHPs instead of RN?
Anyway: Probably sometime next week I'll run back out to the range and do one last chrono test standardizing the BB 125gr at 4.8 WSF, and Xtreme calibration ammo at 115gr JHP at 4.8 WSF, just to have one last check.
For now, though---those seem to be working well for me. Still don't know what the problem is with the Xtreme 124s, but this coming Sunday a couple of other folks should be able to try them in different guns to see what they get.
