.38sp Cowboy load in .357 cases

Bikebreath · Aug 23, 2010

I think I can load .357 cases loaded to .38special Cowboy loads. I have had good luck with 38+p loads, but I wonder how it will shoot with other loads and want to experiment...without breaking anything.

I'm looking at loading Unique at 4.5gr. for around 795-805 fps. No idea what the load pressure might be. Is the .357 case too big to be expanded by such a low load that it would cause, what I heard called, blow-by? Or, worse, could I get pressure spikes?

I searched this and some say it's fine and have been doing this for years and others urge caution and suggest that dacron or kapok fiber for fill.

Here's some additional info:

Case: .357
Load: .38sp Cowboy Action Load
Gun: Ruger SP101, 2.25 Barrel
Powder: Unique
Min load: 4.0 - fps-741
Max load: 4.6 - fps-820
COAL: 1.560"

jimbobborg · Aug 23, 2010

Why don't you try Trail Boss? That's what it's designed for. Especially with lead bullets.

Jim

Bikebreath · Aug 23, 2010

Well, I could, but I have a bottle of Unique and I'd like to use it...maybe not for this load, though. Thanks.

Cowboy T · Aug 23, 2010

I see no reason why it wouldn't work. I have a "Cowboy Action" load that uses Bullseye in a .38 Special case. If I wanted to use a .357 Magnum case, I'd just bump up my powder charge by 0.4 gr. No polyfill or any similar nonsense is needed.

Yes, you can go too low, and that will cause blowback and very dirty cases. Go too low and you can get a pill stuck in the barrel. Not good. I don't have a load book handy, but if that's what you're seeing in your load book, then 4.5 gr Unique is probably a great charge for your purposes.

Bikebreath · Aug 25, 2010

Thanks, Cowboy T. I'm gonna do it.

Baumer · Aug 28, 2010

I download .357mag cases for my wife to use as plinking rounds without any problem. I haven't used unique powder but it should work just fine. I believe hodgon actually provides cowboy action loads in thier reloading data these days. It wont provide specific help with unique but will give you perspective.

Bikebreath · Aug 28, 2010

Baumer said:
I download .357mag cases for my wife to use as plinking rounds without any problem. I haven't used unique powder but it should work just fine. I believe hodgon actually provides cowboy action loads in thier reloading data these days. It wont provide specific help with unique but will give you perspective.

Opps, it's Alliant Power Co.

You got me, though...went to Hodgon and couldn't find it... :lol2:

Here's Alliant's Cowboy recipe for .357:

COAL powder Grs. FPS
1.585 Unique 4.50 859

This is added confidence, thanks.

Biggfoot44 · Aug 28, 2010

Answer #1 : 4.5 of Unique will work fine. Albeit at std .38 spl vels rather than "cowboy" vels .
Answer #1.5 : if using Hogdon charts, their CLAYS UNIVERSAL, aka Universal was designed to be a near exact substitute for Unique by both wt and volume
Answer #2 : if trying for stereotypical "cowboy" loads, try either a fast, easily ignited power ( think Bullseye, Red Dot, similar) or Trail Boss . If trying tp stick with Unique on purpose, work downwards .1 at a time, watching for inconsistant ignition, accuracy less than acceptable, or blowby.

Slimjim · Aug 28, 2010

Id be careful with reduced loads in a large case like that, there is always the chance of powder detonation.

Biggfoot44 · Aug 29, 2010

While there are concerns with certain small charges in large cases, there is plenty of room to move safely down in this situation.

A quick perasual shows off the bat 4.0 in .357 cases, and 3.5 in .38 cases .

Personally I'd use 231 or Trail Boss for less than std vel loads of 600-650 fps- ish loads, but Unique is extremely versatile.

Bikebreath · Aug 29, 2010

Biggfoot44 said:
While there are concerns with certain small charges in large cases, there is plenty of room to move safely down in this situation.

A quick perasual shows off the bat 4.0 in .357 cases, and 3.5 in .38 cases .

Personally I'd use 231 or Trail Boss for less than std vel loads of 600-650 fps- ish loads, but Unique is extremely versatile.

Not looking to go as low as 600-650 fps. Ultimately I'm looking for a non-mag load to shoot steel with a revolver, maybe IDPA. With steel magnum loads are not allowed...bad for the steel and dangerous.

The OP load is a Cowboy load and it is also in the regular .38sp load recommendations, but I guess I misrepresented my intent on the load as needing to be very s...l...o...w, by calling it "Cowboy", although it is. Really just want a less than mag load in the .357 case.

Nice to know Unique is so versatile.

Thanks all!

obiii · Aug 30, 2010

Go Unique!!! I use Unique in my 9mm, 357 MAG, 45LC, 44MAG, and my 30-06!! Love the stuff. In my 30-06 I am using 11-12 grains of Unique, as compared to 45 grains of other powders. Cheap is good!

OB

Bikebreath · Aug 30, 2010

Well, I have Unique on hand, so by not going out and getting Trail Boss while the Unique rots on a shelf...so yeah, in that respect, I'm cheap, too. Yep, cheap is good.

Biggfoot44 · Aug 30, 2010

Versatile is good .Versatile and been around long enough to have institutional memory of proven loads is wide variety of applications is good. And to the extent that there is a "do all" powder , Unique is the closest.
BUT .... Powder isn't that expensive, and having choices is good also. A versatile faster powder is good to have also . Bullseye, Red Dot, and by now 231 also have a long track record of use in variey of applications, and any would be a satisfactory addition for a two powder battery. In the OP's situation as I understand it heavy Unique loads may indeed handle what ever loads he cares for in an SP101, so I'll leave slow powder discussins for another time.

Bikebreath · Aug 30, 2010

I have the Bullseye and it can be a bit of a pain to measure out...rarely the same amount comes out of the RCBS Uniflow Powder Measure. Unique is a little better, but now I don't trust any of them, so I measure every throw, which gets old.

I will be getting some 231 and since it's ball grain I may find that a bit more agreeable to use. If it measured out exact every time it would spoil me...I'd find a way to use it all the time. I'm lazy like that...

Cowboy T · Aug 30, 2010

Bullseye meters very well and very consistently in my Lee Pro Auto-Disk Powder Measure. Same goes for Titegroup, Clays, and 2400. Haven't tried the RCBS measure yet.

You might want to try a .38 Spl +P load since you're using Unique. My light .357 Magnum load feels just like .38 Spl +P in a Ruger Security-Six. Very manageable, very easy to shoot, leaves very clean cases.

Bikebreath · Aug 31, 2010

Ah, maybe I got a bum RCBS measure unit. Might be operator error, too. I'll disassemble and read instructions for assembly and see if it works better. Norton had the same trouble in another thread with Bullseye and the RCBS unit, so I just figured it was Bullseye.

I did a .38+ load using Bullseye and liked what I got, although it was smokey and dirty. Lemme see how this 4.5gr of Unique goes and then I'll try it with 38+ load next.

Thanks!

Bikebreath · Sep 6, 2010

The cowboy loads using Unique at 4.5gr. worked just fine.

Tried .38+p loads, both 4.7gr. and 5.1 with Unique and a light magnum load at 5.5 and they all shot very nicely and much the same. Easy to shot and as accurate as I could make them.

Thanks for all the support! :thumbsup:

JSW · Sep 6, 2010

so that is what you'll being shooting at the next steel match ?

Bikebreath · Sep 6, 2010

JSW said:
so that is what you'll being shooting at the next steel match ?

There's a long and short answer.

Short: No.

Long: I hope to one day. I seem to shoot my revolver better than my XDm and they are the only two handguns I have. Trouble is the revolver is a little 5-shot SP101. I'm already not very good at steel and a revolver is a handicap, using a 5-shot is only gonna make it worse.

I'm interested in getting a 6 or 7 shot revo, but my bank acct. ain't so understanding. One of these days...

Edit: This testing light loads is a road to shooting a revolver in IDPA and steel

.38sp Cowboy load in .357 cases

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