Big ES in 45ACP and 45AR using 255gr SWC

[BKS]

I bought some 255gr SWC to use in my 45acp and 45auto rim.
I loaded the first rounds last night and shot them today. I loaded the acp with 3.5grs of Bullseye and the AR with 4.0grs.
Both bullets loaded to the crimp groove.
Shooting them thru the chronograph today they both averaged 680 +/- fps. But there were huge velocity variations on both loads. They both shot well. The revolver AR rounds had several cylinder fulls where there were 3-4 rounds cutting one hole at 15yards off hand.
I’m looking for any suggestions on lower the extreme spread.

I’m weighing each charge and using a Redding profile crimp die.

I know there is some room to increase the powder charge or change powders.

Does anyone have any experience with this combination that can offer some advice?

[BN]

Experiment with raising the muzzle before each shot to settle all of the powder against the primer and see what your ES is.

[03RN]

I responded to your thread at TOS.

Seat deeper. I'm surprised the acp rounds function. And try upping the charge.

[revchuck38]

Define “huge”.

You seated them to the crimp groove, but did you crimp the case mouth into the crimp groove? And least for the AR rounds, that should help.

[BKS]

150fps or more for 4 out of 12 shots.

I am going to experiment with more crimp and 03RNs suggestions

[revchuck38]

^^^^Yeah, that's huge.

[358156hp]

How's the accuracy?

[BKS]

These are just punching paper and hitting steel loads. At 15 yards shooting offhand I would have 2-3 rounds touching in each group. The accuracy potential is there. I only loaded and shot about 40 today.

[Malamute]

You may have difficulties if you crimp the case into the groove on 45 auto rounds since they headspace on the case mouth.


I loaded 100 rds of the Lyman 255/260 gr SWC Keith designed bullet (dont recall the mold number) in 45 auto way back. I seated them about the same length as normal loads so they fit in the magazine, the case mouth was just shy of the sharp shoulder. I taper crimped them. They ran fine for that 100 rds in an unmodified Colt Combat Commander. Small sample, but it was not unheard of to load that bullet in 45 auto then. I think the common load was around 6 grs Unique, but it may have been more, velocity was 850-900 fps or so according to the lore. Not many people had chronographs then. Not much of an answer to the extreme spread question, but Id guess a little more velocity and powder may help, and it doesnt cost that much to try some.

Edit: Found this, which ive seen before. It correlates the load info I recall. I think upping your charge may help some in the ES issue, and perhaps changing to a little slower powder thats bulkier may also.

http://www.castpics.net/subsite2/ByC...0.45%20ACP.pdf

[Frank500]

Malamute is correct! Add some appropriate slower burning powder like unique or power pistol. I think your extreme spreads are dangerous and I also would not shoot loads that anemic. Good chance they’ll bounce off the backstop.
I’ve shot lots of 250 grain in the 1911 close to and exceeding a 1000fps. Pretty good tool for large predator defense or hunting.