A Tale of Two 45 Loads

[jski]

Just got back from the range with my new LabRadar chronograph. Both these loads were shot using my 45 Colt S&W Mountain Gun with a 4” barrel. Both used Alliant’s Unique powder. And both used Berry’s 250 gr bullets.

A) Full length 45 Colt brass with 9 gr of Unique: 900 FPS

B) Starline Cowboy Specials brass with 6.7 of Unique: 750 FPS

I got the load for the Cowboy Special by using data from 45 ACPs.

Do these results (performances) seem a bit low?

 

[PapaG]

No.

 

[whughett]

No, seem in line with what I’ve done with the caliber. I need to buy some of the shorter brass, or trim back some 45C. Several bullets I like won’t fit the conversion cylinders unless seated deep enough to look ridiculous.

If those bullets have no crimping groove your not going to get the velocity you would with a bullet that does. Slower burning powders generally rely on a heavy/heavier roll crimp to increase pressure.

 

[Charlie98]

Looks about right to me, that's what I get out of my 5.5" Vaquero barrel with the same load... actually about 940fps.

 

[FROGO207]

Remember the original 45 Colt was not a high pressure cartridge and those older guns need gentler loads. Yours can handle a higher level so the Ruger only Loads will work for you if you want more speed. Those speeds sound about in the range to me as well. But the cowboy brass load will be an experiment if you need to go higher due to the smaller case volume and lack of data. If you use the crono to monitor the speed and keep it to the Ruger only max speed and work up slowly and watch for problems you should have close to the same pressure at the same velocity using the same propellant in smaller amounts. Or you could ask the powder company if they might suggest a safe load with Unique using those components.

 

[GarrettJ]

Also keep in mind most load data for that caliber was generated using longer barrels (7.5” give or take). Your 4” barrel will show a noticeable reduction in velocity.

My 4-5/8” barrel doesn’t typically make published velocities either.

Don’t sweat it. Just work up some loads that are safe and shoot well in your gun.

 

[WrongHanded]

Yours can handle a higher level so the Ruger only Loads will work for you if you want more speed.

To me, this sounds like a dangerous assumption. I don't have any idea how strong the S&W Mountain Gun in .45 Colt actually is, but I have my doubts that it's as strong as a Ruger Blackhawk.

Here's some info on the destructive testing done to the Ruger Blackhawk to assess the limits of its capabilities with modern loadings of .45 Colt:

https://www.johnlinebaughcustomsixguns.com/writings

I'd suggest that the OPs gun would likely be as strong as the Model 625. Which would mean .45 ACP +P pressures should be okay. However, I'd get confirmation on chamber wall thickness, just to be safe.

 

[murf]

my powder forward/back test: .

i'm all over the target and the bullet weighs 255 grains, but the load is there and the velocities are up in the left corner. by the way, the barrel length on the Blackhawk is 4.625".

luck,

murf

p.s. forgot the best part: barrel up, great group!

 

[FROGO207]

Wrong handed you might be correct there but depending on the frame/cylinder it might be OK. If it is the same frame as my model 29 that one is good for 44 MAG pressures. A little research is in order if the OP needs a stout load.

 

[WrongHanded]

Wrong handed you might be correct there but depending on the frame/cylinder it might be OK. If it is the same frame as my model 29 that one is good for 44 MAG pressures. A little research is in order if the OP needs a stout load.

I completely agree: it might be okay.

So in the Linebaugh link from my previous post, he goes into detail about the frame, but states that the cylinder in the BH is the weaker part of the gun. So yes, the frame needs to be as strong as the .44 mag version. But given that, the strength of the cylinder is really what needs to be determined. The cylinder may be the same diameter as a .44 N frame gun, but the steel and heat treat will be a factor, as well as the wall thickness of the chambers.

I just don't want to see the OP blow up his gun or get hurt. I bet someone on a S&W forum would have some more information though.

 

[WrongHanded]

I googled and found this thread. Somewhat relevant.

https://www.thehighroad.org/index.php?threads/how-strong-is-the-s-w-model-25-in-45-lc.721407/

 

[FROGO207]

Yeah I remember that thread now. The cylinder is the weak point for sure and Ruger only loads look to be too much. Thanks for catching that.