Cowboy Action Light Loads for .357 Mag cartridges - PRIMERS Standard vs Magnum?

[SteveK]

I'd like to load up some 150gr LFP bullets for next season and keeping the velocity as far below 900fps as can reliably be done. I'm thinking that with about 4grs of Unique the cartridges would be under 900fps. So why not forget about using magnum primers and just use the standard small pistol primers? After all, my .45ACP shoots just fine with a little powder and standard primers. Why spend the extra doe for magnum primers when a big bang isn't what I'm after anyway? Right? (or not?)

Your thoughts?

[dannyd]

Both primers will work, you may want to look at a 125gr LFP works well for clean matches.

[Walks]

In 30+yrs of Cowboy shooting I never heard of anyone using Magnum Primers except in Long Range BP Rifle.

No Unique that low. Use Clays, Titegroup, WW231 or Bullseye.

[SteveK]

Thanks... I believe you're right about using a lighter bullet. I'd use a 125gr LFP mold if I hadn't gotten my 150gr (158gr?) for dirt cheep

[SteveK]

In 30+yrs of Cowboy shooting I never heard of anyone using Magnum Primers except in Long Range BP Rifle.

No Unique that low. Use Clays, Titegroup, WW231 or Bullseye.

Hmmm. I have a little 231 at home and POUNDS of Unique... What about 700X? I have a bunch of that too.
It's too close to Xmas to order a new powder.

[JoeJames]

No need for Magnum primers. You're just essentially shooting 38 Specials out of a case that is 1/10th of inch longer. Same theory as I have been using in light 44 Magnum loads. My rule of thumb for light 44 Magnum loads was a little less than a 10th more than my regular 44 Special load (44 Special using 6.5 grains of Unique - I upped it to 7 grains of Unique in a 44 Magnum case, and the velocity was comparable). And regular large pistol primers in my case.

[Silver Jack Hammer]

I wouldn’t think Unique would burn reliably at such low pressure

[dverna]

In 30+yrs of Cowboy shooting I never heard of anyone using Magnum Primers except in Long Range BP Rifle.

No Unique that low. Use Clays, Titegroup, WW231 or Bullseye.

What he said. And use .38 Spl cases.

[JoeJames]

I wouldn’t think Unique would burn reliably at such low pressureIn my Rossi R92, very consistent velocity averaging 1150 fps, and quite accurate.

[Silver Jack Hammer]

In my Rossi R92, very consistent velocity averaging 1150 fps, and quite accurate.

4 grains of Unique is giving you 1150 FPS out of your Rossi ‘92 with 150 gr. boolits in magnum brass?

[Hick]

I get 950 fps with an Ideal 358156GC flat nose cast bullet and 3.7 grains of 700x out of my Henry rifle in .357. That's with magnum primers. With standard primers it's a little lower velocity (more like 925). I get similar results with the same bullet and 4 to 4.5 grains of W231.

[SteveK]

I get 950 fps with an Ideal 358156GC flat nose cast bullet and 3.7 grains of 700x out of my Henry rifle in .357. That's with magnum primers. With standard primers it's a little lower velocity (more like 925). I get similar results with the same bullet and 4 to 4.5 grains of W231.

That's so handy to hear! Thank you very much ! First off, I have loads to 700x and Unique. When I make the loads I'll be shooting them out of a pair of Evil Roys and a Uberti 1873 Winchester knock-off.

Merry xmas to you all!

[SteveK]

What he said. And use .38 Spl cases.


I'll be using the Starline 357 brass I bought at an auction. Ya gotta save $ where ya can, right?

[SteveK]

I wouldn’t think Unique would burn reliably at such low pressure

I was worried about that too! It seems that 3-4 grains of Unique might mean more "echo" in the case than powder. But when you think about it, my 45ACP has always shot darn good light practice loads for me, albeit the cartridge is much shorter. I'll have to try out a few testers and see how it shoots in a 357... at least I won't have to fret over-pressure or cycling issues.

[smkummer]

I use 700x in my 44 special/mag. and 45 cowboy loads. It works great. It works for 38/ 357 as well except that it doesn’t meter well below about 3.6 grains with my lee pro 1000 so I use bullseye. Of course you don’t need magnum primers unless you just want to use them up or your load is close to minimum and you get a little extra security with a magnum primer to not stick a bullet.
If 38 cases cycle well in your rifle, then use those as 38 brass give better ignition with light loads given the same amount of powder. You can get good results as low as about 3 grains 700x and a 150 grain bullet in 38 special.

[rfd]

starline .357mag brass, cci standard spp, 4.0 to 4.8 grains of w231 dumped with a harrells schuetzen measure, under a 125 grain whatever bullet. i no longer bother to cast for handgun bullets and prefer the hi-tec coated kind from precision and acme, they're cheap enuf with less smoke and no leading issues. in a 45oz ruger blackhawk there's not much recoil and the load is more accurate than i am.

232563

i'm a lousy handgunner, but with the above gun and 4.8 load i can single hand quick fire a buncha rounds at 10yds and do ok, which i think is good enuf for cowboy.

232564

[jonp]

Considering the velocity your after can I ask why your not using 38sp? Use standard primers for that in any case, magnum not needed.

[MT Gianni]

Magnum vs standard primers is all dependent on the powder used. In general ball powders do best with magnum, flakes are ok with standard.

[TNsailorman]

Gianni, that has been my experience over the years of reloading. Ball powders seem to be a little harder to ignite than standard powders. I really like Unique powder but it burns dirty (ash cinders) at low pressures, almost like black powder. But get it up to operating pressure and it is a good all around powder. It does quite well with lead bullets in the .41 magnum and .45 LC. my experience anyway, james

[AaronL]

Take a look at Trail Boss. It is designed for light loads. I use it for cowboy action shooting as well as most of the shooters I compete against. It works well in any handgun caliber that would be used in cowboy action.

[LUBEDUDE]

I'll be using the Starline 357 brass I bought at an auction. Ya gotta save $ where ya can, right?

Understood, and you’re going to love CAS! A lot of good, helpful folks. Watch, listen, and learn from the veteran cowboy shooters.

But unless you are talking about thousands of 357 cases, you’ll switch to 38s. When? That depends upon your learning curve and frequency and duration of participation.

[charlie b]

FWIW, I have always used std primers in my light .357 loads. Most of those are .38spl or .38 +P level loads. I only use mag primers if I am shooting heavy loads.

Why not use .38 cases for light loads? I just never had good luck with the longer bullet 'jump'. If I were to want a weapon for light loads only I would try to find a .38spl chamber.

[gpidaho]

I think Steve's goal here is to use what he has on hand and what he has come by at a steal of a deal. Sure, there are a million good 38spl loads and an equal amount of good 357 ones. With what you have on hand Steve, I would use the 700X and there's no need that I see for a magnum primer unless a friend gave you a few thousand of them. In that case use them, it won't hurt anything. Gp

[sniper]

Steve: 5.5gr Unique/150 gr RCBS cast boolit/4" barrel /357 brass/standard primer=~860 fps chrono'ed. 4.5-5.0 gr. Unique should get you right about where you want to be.
I've never thought it is an advantage to use .38 Spl. brass, unless, like Skeeter Skelton, a person could get it free. With mild loads, average brass cost should not be a factor. Good luck!

[35remington]

Try chronographing light to moderate loads of Unique in 357 cases with powder near bullet then powder near primer.

Expect the disappointing results you will get.

[SteveK]

I think Steve's goal here is to use what he has on hand and what he has come by at a steal of a deal. Sure, there are a million good 38spl loads and an equal amount of good 357 ones. With what you have on hand Steve, I would use the 700X and there's no need that I see for a magnum primer unless a friend gave you a few thousand of them. In that case use them, it won't hurt anything. Gp

GPIDAHO, You pretty much understand my situation perfectly. To me, its all a matter of trying to live with what I have ...safely, without damaging my stuff. Shooting store-bought 357MAG rounds through my Cimmaron Evil Roy pistols really beats the hell out of the pistols [not to mention my hand], but not so much the knock-off 1873 rifle. Also keeping in mind the safety issues presented by ricochet rounds or lead splatter made light loads a must for me. This was my first venture into CAS. If I was to start all over again I'd have probably looked harder into acquiring/reloading 38 SP ammo or maybe 45 LC (which also seems to be super popular among the folks where my shooting events are being held.) Oh well, live and learn.

Just the same, I'm very grateful to you folks for all your help. Thanks a bunch!

[SteveK]

Try chronographing light to moderate loads of Unique in 357 cases with powder near bullet then powder near primer.

Expect the disappointing results you will get.

I'm afraid you lost me making the distinction between "powder near bullet" vs "powder near primer." I can't see how to force either situation in a cartridge case.

[35remington]

Tip barrel steeply down. Level. Fire.

Tip barrel steeply up. Level. Fire.

Expect horrid results over chronograph. 38 Specials are bad enough. 357s are worse. This models handling variation of the gun. Putting farty loads in 357 cases with Unique is synonymous with extreme velocity variation.

[SteveK]

Ya know, after I though on this for a bit I guessed that this is what you meant. Clever test! Oh well... as long as they come out of the barrel straight velocity variation might not matter very much... From what I've seen, all the targets seem to be less than 20 feet away. I guess cowboys weren't very good shots unless it was an ol' Winchester '73. Thanks for splainin'.

[SteveK]

Steve: 5.5gr Unique/150 gr RCBS cast boolit/4" barrel /357 brass/standard primer=~860 fps chrono'ed. 4.5-5.0 gr. Unique should get you right about where you want to be.
I've never thought it is an advantage to use .38 Spl. brass, unless, like Skeeter Skelton, a person could get it free. With mild loads, average brass cost should not be a factor. Good luck!

Thanks sniper! I'll give a little heavier load a try. When it warms up a bit, I'll take the chrono out to the range and see what they do.

[35remington]

I’ve seen some cowboy shoots were 50 yard shots were required. They don’t all have to be big and close. If they are not, give some real thought to using more consistent loads than lowest possible pressures with partial casefuls of poorly suited powders.

[Finster101]

.38 Special brass just makes a .357 harder to clean. I prefer not to deal with the carbon ring.

[SteveK]

I’ve seen some cowboy shoots were 50 yard shots were required. They don’t all have to be big and close. If they are not, give some real thought to using more consistent loads than lowest possible pressures with partial casefuls of poorly suited powders.

Holy smokes! I've never seen such a long shot in Janesville CAS events. Well, I won't give up looking for a better match loads. Thanks!

[35remington]

Here at the Columbus NE range such a thing was at the state shoot a few years ago.

[sniper]

Trailboss also comes to mind. Good case fill. I got caught up in the "The Minimum load that will make your gun go Bang" madness a decade or two ago. There was this article in one of the gunzines which recommended reducing your standard load (in my case, Unique) by 50%, then doing it again. I did, :shock: which lead to a little boy at the range asking his Mom; "Why is that man hammering on his gun?" as I was knocking the stuck boolit out! :oops: It seems that I have seen the same guy, or one of his disciples on YouTube..."SHOOT your gun with 2.7gr Unique!"...or some such. I haven't bothered to watch!

[smkummer]

.38 Special brass just makes a .357 harder to clean. I prefer not to deal with the carbon ring.

I have experienced this with revolvers but that is over time and if they were not cleaned each time after shooting. I am going to keep an eye on my new to me 1996 Marlin 1894C. My test for my 357 revolvers after shooting 38 ammo and cleaning is if a 357 drops into each chamber easily.

Anyway Lee’s 358-125 RF runs perfect in my gun and at 10 yards is a tight group standing. I only fired 15 rounds and a 357 chambers easily so I’ll have to see after a 6 stage cowboy match and 60 rounds if my cleaning is adequate. Also, in my situation, I have to use 38 special brass in order to fit 10 rounds in a 18 1/2” barrel rifle for cowboy action.