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What are you running for max loads in .357?

I have been such a .44 fan that I have never messed much with .357s. That changed in that I found aGP100 with the slab side 4.2" barrel that I could not resist. Ordered 500 Starline cases and 158 XTPs and got ready to load and realized that I don't own a single small pistol primer. From my research, it seems AA9, 2400 and 300MP outpace 110/296 for velocity, which makes me think I should order standard and not magnum primers.

H110 OR Win 296 with CCI 550 Primers with the bullet you listed.

I've had the best accuracy with H-110. I use standard small pistol primers, IMHO the 357 doesn't require a magnum primer to light off ~15 gr of powder. I only shoot cast, either 160 or 200 gr.

^ This ^

I have a lot of 110/296. It just seems to lag AA9 in particular by about 100 fps in what I have been reading.

14.0 gr. 2400 with a standard primer or 16.0 gr. 296 with the 158 XTP are safe maximums in any good .357 revolver. The GP-100 is strong and can probably take a grain more of each but I see no reason to - it just shortens brass life and it won't add all that much extra velocity in that 4" barrel. While I've never done any real testing to prove a magnum primer is needed with 296 that's what I use since most of the sources I've read recommend it with ball powders.

I like the old .357. Heavy bullet, hand stinging loads in the .44 and .45 get all the press these days but you can still do a lot with a 158 or 180 grain bullet in an accurate .357 revolver.

Winchester SP Magnum primers are very hot. Do not substitute from another at max loads. Even with ball powders.

You heard it here first.

Accurate arms was my reference. They say reduce 15% (no typo). Seconded by Winchester Loading booklet.

The powders mentioned already work well.



<another handloader wanting super max loads> Gee wiz.

Go back to your .44 or get a .41

Another vote for the classic 2400.

15.5grs of H110 and Hornady 158gr XTP

Gibby,

I do appreciate your advice regarding primers. Fortunately, I don't use Winchester primers because of other inconsistencies in recent years.

Regarding your other point, I have and use both .41s and .44s and several of each. I have the .357 for other uses and for my use for the GP100, I see no reason not to find the best performing powder for safe, maximum loads. My understanding is the GP100 should stand up to tens of thousands of such loads and my intent once such a load is established is to buy components for several thousand rounds and use the gun.

For bullets 140 grains and up I use Winchester 296 and Federal 200 primers with WW brass.

For 110 to125 grain bullets I generally use HS6 or Win 231 and standard small pistol primers, either Federal 100s or WSPs.

I find that it definitely DOES make a difference in accuracy when I use magnum primers with the fast powders or standard primers with the very slow powders. Not a positive one.

Tom

I use this load in my Marlin 1894C 18.5" carbine and used it in a Ruger Blawkhawk 6.5" handgun.
Federal cases and Federal GM200M primer
16.0grs of H110 powder with a Speer 158gr. soft point seated at 1.580" COAL
I use a crimp from a Lee Factory Crimp Die.

I am unaware of problems with Winchester SP Magnums primers. Their other sizes and styles in later years, yes. The powders your going to use for top loads will be on the slow side relatively. Many years ago, Winchester was known for having the hottest loads in the factory loadings in that caliber (using 296). I have had very good luck using WSPM primers with the .357 mag. The GP100 is a very good double action test gun for the .357 magnum. The mass of that cast frame absorbs a lot of energy. The stainless frame is more resistant to flame cutting of the top strap. You are talking about tens of thousands of rounds. Great for becoming a good shooter. The lock time seems a little slow compared to the S&W 's and Colts. Then there is that Ruger trigger. Not dogging the GP100, I have two of them. Very rugged.

The long powder column in the .357 using slower powders is benefited by using magnum primers. Less muzzle blast is one benefit. Especially the ball powders in a four inch barrel. Like 458 Lott suggested, good for jacketed bullets. Primers are very hot in burning temps. Hotter than the powder burn temps. Magnum primers, in my experience cause more leading in cast (no gas check) bullets. 158gr bullets work very well in the .357 for all around use.

Try not to develop a flinch with those hot loads and muzzle blast. Nobody has ever died from recoil and muzzle blast from a .357 Magnum.

AA#7 (higher nitro glycerin percentage than the other powders listed here) gives a very accurate load using standard primers for moderate loads. But its not going to be the max loads your looking for. Less sensitivity to powder positioning is another plus. But a full case of slow burners doesn't have that problem either.

You did not buy that GP100 to shoot .38 special wad cutters, so enjoy.

I have found that h110 needs a federal magnum primer to light off the correct way. Here is my load that is pretty fast and over book but will still shoot really accurately from my 4 inch .357 that a whitetail within 100 yards better be really scared.

16 grains h110
starline brass
federal magnum primer..non match version
158 grain xtp

1280 from a 4 inch pipe.

Thank you, Gibby. I probably won't shoot tens of thousands of rounds through this gun, but if I do, I know it will stand up to it. It's unlikely this is the gun that will lead to me developing a flinch.

In my experience testing loads over a chrono when you are using a barrel 4" or so and under then I have indeed gotten higher velocities (and less flash and less blast for that matter) using Accurate No. 9 vs H-110/296. I have seen this play out with multiple Rugers (Security-Six, GP-100, Blackhawk) and several S&W's (66-5, 686-6, 686-6). When you get to a 6" barrel then slower H-110/296 comes into its own. In lever-actions H-110/296 for sure runs away with it if max speed is your goal. This was all using CCI 550 magnum small pistol primers. I'm not a fan of the Winchester primers. After testing lots and lots of powders, I am settled with Ramshot True Blue and Accurate No. 9. These two can handle it all in 357 and 44 loads from mild to wild. I use True Blue for all loads with bullets under 158 grs. Also use it with 158-165 gr medium cast loads (say up to 1100 fps from a 4"). Then switch to No. 9 for full powder stuff like 158-165 grs at 1200-1300 from a 4" barrel.


Good Luck,
Mark in GA

What bullet weights did you chrono? I'd expect that with the 125's, but would also expect H-110 to still be the speed king with 180-200 gr bullets.

You're the only person I've seen who's mentioned using True Blue. I stumbled onto that powder having bought it for a 9mm but experimented with it in other calibers and now use it for moderate loads in my two .357 revolvers with 158 gr. cast bullets - those are 6 1/2" and 6" respectively. It also worked very well in the .44 Special and .45 Colt for that purpose. An interesting coincidence is that charge weights I settled on varied by 2 grains - 7.0 for the .357 which gives just under 1100 fps fps in the 6" GP100with a 160 gr. cast bullet, 9.0 for the .44 with 245 grain cast and 11.0 in the .45 Colt with 250 cast.

Obviously it meters like water and unlike some other ball powders burns well at that pressure range.


Oh yeah, it works great for 9mm 124 grain loads, too.

I've gotten 1390 FPS out of my 4" 357 with a top charge of H110/296 with 158 grain Gold Dots. Barrel length doesn't dictate powder burn rate.

That's a good velocity. What charge weights were you using?