Help with estimating .45 ACP velocity in longer barrel.

[roverboy]

I'm going to do a project with a 20" barrel liner in probably a shotgun barrel. I was wondering if the .45 ACP would suffer in a barrel this long with standard loads. I have seen handloads with slower powder that do good in longer barrels. Thanks

[Outpost75]

With a soft iron shotgun action having a large, unbushed firing pin, I would not be inclined to exceed factory .45 ACP pressures of about 20,000 psi. I have a .45 ACP rifle which John Taylor built for me on a pre-WW1 H&R .44 shotgun action which shoots well with factory loads and equivalent handloads.

Attachment 258588Attachment 258586Attachment 258587

I also have a Marlin 1894 Cowboy which John set back and rechambered from a .45 Colt to .45 ACP and it handles hot loads which equal .44-40 black powder velocity, but I would not use those in the iron-frame H&R.

Attachment 258589

.45 ACP Standard Pressure Loads In Rifle and Colt New Service Revolver

.45 ACP Velocity _____Colt New Service 5-1/2”__H&R 20”
Federal 45D 230-gr.JHP____854, 17 Sd________932, 33 Sd
TW55 M1911 Ball_________839, 8 Sd_________944, 19 Sd

Saeco 230-grain #954 FN, wheelweight alloy, sized .452”, Lee Liquid Alox

4.5 grains Bullseye_______817, 16 Sd_________982, 6 Sd
5.0 grains Bullseye_______849, 10 Sd_________1047, 6 Sd

Saeco 260-grain #955 FN, wheelweight alloy sized .452”, Lee Liquid Alox

4.0 grains Bullseye________693, 10 Sd_________886, 12 Sd

1894 Marlin Carbine Velocities .45 ACP+P+ vs. .44-40
I experimented with #2400 in a converted Marlin 1894 .45 ACP carbine with 20” barrel. DO NOT try these in an M1911 pistol, but only in the New Model Blackhawk convertible or a suitably strong rifle which supports the case well.

Test loads all assembled in Federal NT cases with Federal 200 small rifle primer.

Control - HM2-453-200FN Cowboy, 5.5 grains old Hercules Bullseye 1054 fps, 4 Sd, 15 ES (951 fps, 11 Sd, 33 ES in 4-5/8" Ruger BH)

H&G68 200-gr. SWC, 16 grs. old Herc. #2400 1433 fps, 11Sd, 34 ES

Accurate 45-240D, Auto Rim flatnose bullet, 16 grs. old Herc. #2400 1375 fps, 15 d, 40 ES.

Cases extracted and ejected easily with no excessive pressure signs, no barrel leading. Bullets cast of wheelweights lubed with Lee Liquid Alox. The .45 ACP +P+ loads fired in the Marlin carbine grouped about 6” for 10-shot groups fired at 100 yards, typical performance for an iron sighted, 5 lb. cowboy gun.

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.44-40 loads I fired for comparison from my 20” Marlin 1894S, Starline cases, CCI300 primers.

Accurate 43-200Q, 15.4 grs. old Herc. #2400 1178 fps, 8 Sd, 23 ES

Accurate 43-200Q, 6.5 grains old Herc. Bullseye 1142 fps, 12 Sd, 43 ES

Accurate 43-200Q, 23.5 grs. RL7, 1315 fps, 36 Sd, 133 ES

Iron sight .44-40 groups were also in the 6” range for 10-shots at 100 yards with iron sights. I find this acceptable performance for a lever-action carbine firing handgun ammunition.

[onelight]

Outpost strikes again with more great info than expected .
Good stuff.

[roverboy]

Thanks I was just wondering if standard loads increase much in the 20".

[jcren]

Some loss over 16" generally. These guys have a lot of useful data.
http://www.ballisticsbytheinch.com/45auto.html