Single Action spreads and deviations

[Deleted]

Testing my new Garmin xero chrony is giving me some interesting stuff to consider. Today I checked one of my favorite loads 11.3 grains Longshot behind 285g MP 270 SAA solid pc. Also the same powder charge with Mp 454 640 penta 260g.

Mp 454 270saa solid 285g
Cci300 primer
11.3g Longshot

Clements bisley 5 1/2
Avg 1095
Spread 106
Std dev 32

Harton 4 5/8 bh
Avg 1097
Spread 19
Std dev 6

TylerGW 5 1/2 nm ft
Avg 1114
Spread 58
Std dev 19

Bob Baer 8 1/2 om bh
Avg 1058
Spread 116
Std dev 42

Interesting that the long barrel is slowest fps avg. The midframe ft gun is fastest?
My Clements bisley bh typically has very high spreads and deviations. Ironically it is my most often, most accurate gun. The Harton and Baer guns are pretty new to me, and I need more time behind them. But the Harton blackhawk is quickly moving into my favorites list.
Brian Pearce estinmated the same load in his mid level 45 colt data at 1053 from 5 1/2 nn ft.

I also tested the mp 454 640 bullet which I plan to test much more because im seeing excellent accuracy.

Mp 454 640 penta hp 260g
Cci 300
Longshot 11.3g

Clements bisley 5 1/2
Avg 1107
Spread 140
Std dev 40

Harton bh 4 5/8
Avg 1086
Spread 34
Std dev 10

Clearly the Harton bh is running really well numbers wise. I never have figured out the deal with the clements bisley. It has developed a rough fire cracked barrel face and forcing cone but it continues to shoot accurately.

Each of my guns responds differently to these loads. Ive found Longshot to be excellent for accuracy. BUT i get quite a bit of smoke and powder burn all over the frame and cylinder. The brass is cleaner than the W231 loads I tested today as well.
Its fun testing this stuff. I dont know what good it does reporting but maybe you get something out of it.

[longoval]

Interesting data. Makes me curious how the barrel/cylinder gaps vary between builds and how that corresponds to ave velocity and ES.

[bula]

I finally got a chrono after many years. As you are finding, there will be some surprises. As someone here would say, but my wording, let the target talk to you. Likely you know that.

[bigbore5]

After I got a chrono I was surprised to see exactly how "slow" my #1 game hammer bullet was actually moving. I just tried a few powders until I found the most accurate and started killing deer with it. Wouldn't have thought a Keith 357 bullet at 1100fps was that good.

[bradshaw]

professor.... first thing I’d do with those cast bullets: reduce the charge 1 to 2 grains and DEEP SEAT.

I would target your Harton and Clements @ 50 & 100 yards. Anticipate vertical stringing from from high Extreme Spreads. If verticals are present, and you’re not fighting the gun, the fastest shot will print lowest, with the slowest shot highest on target. The longer barrel time of the slow shot produces more muzzle lift before bullet exit.

A list of possible causes of high Extreme Spread, I would check mainspring tension and, second, firing pin protrusion. May or may not be a factor. A call to Hodgdon tech may help.

The .45 Colt has a voluminous case, a natural for deep seating of cast bullets.
David Bradshaw

[Deleted]

Nov 7, 2023 9:50:08 GMT -5 bradshaw said:

professor.... first thing I’d do with those cast bullets: reduce the charge 1 to 2 grains and DEEP SEAT.

I would target your Harton and Clements @ 50 & 100 yards. Anticipate vertical stringing from from high Extreme Spreads. If verticals are present, and you’re not fighting the gun, the fastest shot will print lowest, with the slowest shot highest on target. The longer barrel time of the slow shot produces more muzzle lift before bullet exit.

A list of possible causes of high Extreme Spread, I would check mainspring tension and, second, firing pin protrusion. May or may not be a factor. A call to Hodgdon tech may help.

The .45 Colt has a voluminous case, a natural for deep seating of cast bullets.
David Bradshaw

I will try this. It will save some powder.