Now comes the interesting part. The BUL pistol I just bought brings the number of 9mm handguns up to FOUR, which might be a shock to some of you who think that I never shoot anything smaller than 50 caliber. I have my old tried, true, and very well worn 1971 Browning Hi-Power, a rather rare Tanfoglio GT-41 in 41 Action Express that I managed to find a 9mm barrel for, and my SIG P226 in 357 SIG that I purchased a Bar-Sto 9mm conversion barrel for. Since the BUL is only a 3.6" barrel, the question of velocity loss is a valid question, so I decide to load up identical ammo for all 4 pistols. For the record, the GT-41 barrel is 4 5/8" long, the Browning barrel is 4 1/2" long, and the SIG barrel is 4 1/4" long. So off I go to the Oakdale range with my Millenium 1 chrono and 4 guns and 4 boxes of ammo, and start shooting.
To cut to the chase, the results are shown below: The data is all quite linear, and in general the Standard Deviation for the 5 shot strings ranged between a very low 4 FPS up to about 12 FPS, which is still pretty good.
As can be seen, there is definitely a velocity penalty for going from a 4 1/2" barrel down to a 3.6" barrel, and the loss in velocity works out on average to be 40 FPS.
Now, there is a considerable discrepancy between the velocities reported here and what the Lyman #49 manual says. About the only thing I can think of is that the Red River bullets were softer than Lyman #2 alloy (90% lead, 5% antimony, and 5% tin) and thus were "stickier" and had more friction going down the barrel. This is supported by the fact that the lead fouling in all 4 guns was pretty considrable after 50 rounds, and I don't remember my Lyman #356402 bullets ever leading that badly after hundreds of rounds in my Browning.
Finally, there is the question of why the 4 1/4" SIG barrel produces faster velocities than 4 1/2" barrels with the same loads, and for this I have no answer. It could be that the surface finish of the Bar-Sto barrel is much better than the other guns, but this is just a guess, and there are so many other possibilites that I don't even want to go there. About the only thing that IS clear is that having a slightly shorter barrel may NOT mean that you will see a velocity drop, and that guns are as individual as people are. If you don't chrono it, you'll never know how your gun is actually performing.
UPDATE: The difference between the velocity I got in the above test and what the Lyman #49 manual said I should get was nearly 150 FPS, and I was wondering if it could have anything to do with the softness of the cast lead bullet I used. There was substantial leading in all 4 guns in only 50 shots, and a poster on the local board reported leading with Red River bullets even with mild 45 ACP loads. Seeing as I had a good supply of real Lyman #356402 bullets that were made with hard Lyman #2 alloy (90% lead, 5% antimony, 5% tin) I decided to load up two boxes of ammo identical to what I had already done, with the single change being Lyman #356402 bullets. Due to the difference in nose length, the OAL of these rounds was 1.110". I decided to use the 9mm Browning and the SIG P226 9mm for the testing, and the chart is shown below:
As it turns out, there appears to be very little difference between the two bullets, which is probably a good thing overall. If the Lyman #356402 bullets had somehow run near the 1264 FPS speed listed in the Lyman #49 manual, then that would mean bullet hardness was a major factor in velocity, and that would touch off one hell of a debate and problem for different cast bullet manufacturers, and also make life VERY uncertain for handloaders who don't own chronos. As it is, the bullets run nearly the same speed, but with the Lyman #356402 bullets the barrels were nearly spotless after 50 rounds being fired through them, so there was a major difference in leading between these two kinds of bullets.
In conclusion, I still have no idea how the Lyman data can vary so much from the actual results I got, but it must be that the Universal Receiver and barrel combination they use is substantially different in some way from any of my pistol barrels. Lyman used Federal brass instead of Winchester, but I can't imagine getting an extra 150 FPS out of another major brand of 9mm case.
