For years I have used W296 for reloading 357's for shooting in my model 27 and I was looking at the loading recommendations in my manuals and on Hodgdens website and it is interesting the variations in recommended loads.
All of what follows are for a 158 grain JHP

The website recommends 15-16.7 grains of either 296 or H110 w/max CPU of 40,700
My old Winchester booklet has 16.6 grains of 296 at 39,500 CPU
My Speer #10 has 15.8-17.8 grains of either 296 or H110 with a max of "slightly under" 46,000 CPU
My "New to me" Speer #12 has 13.9-15.5 of H110 and 13.2-14.7 of 296 with a max pressure of 35,000 PSI (I know PSI and CPU are not the same) with a much lower velocity than the other sources.

Also interesting that the older manual says use the maximum load "with caution" I remember using those maximum loads once and then deciding that backing off from that would be a good idea.

I am not making any statements about which manual to use just found the differences interesting.

And if we ran the test again today with a different barrel and instrumentation, you would get a different answer. Certainly very different with a real gun versus a test barrel.

Loading max loads without a chrono is adding one more risk factor.

__________________
Science plus Art

That's why I don't load them that way I found it interesting how much lower the loads are in the Speer #12 manual.

Sorry I posted this in the Ammo section not the reloading section. If the powers that be could move it that would be great.

thanks

I quit using H110 for .357 magnum because in spite of the big flash and bang, the velocity wasn't there. I now load 14.5g of 2400 with a standard SP primer.

POSTSCRIPT: I want to emphasize the importance of using standard primers with this load. I know many sources recommend magnum primers. I have tried both and found a significant difference.

My basic Rifle load for 357 Magnum is 14.8 grains of H110 witha 158 grain Hornady XTP. Source for the load recommendation was the Hornady manual and I chose this load because of the exceptional accuracy from my 1892 Winchester. For my Handgun loads I prefer to use Accurate #9 for the high energy loads and #5 for low recoil 357 Magnum Lites. I do almost all my Handgun shooting at indoor ranges and found rather quickly that the drama of H110/W296 really wasn't worth the 30-40 fps gained over using #9.

I'll also note that in general the loads in the Hornady #9 seem to trend towards lighter powder charges than most other sources but just about every load I've worked up using Hornady's data has proven to be exceptionally accurate. I really like Hornady's approach, they seem to emphasize accuracy over energy and the result makes for a more accurate load that allows me to stretch a pound of powder further.

Another good example of why I tell people that they need a chronograph to find out fps of a load in their gun. Loading manuals only tell you what their barrels and load did. It doesn't tell what your gun will do with that load. Larry

You'll find this with virtually every cartridge you load for. I think it mostly stems from the differing bullets, as jacket thickness and bullet seating depth affect the loads. Not everyone owns every manual, so if you're loading Hornady bullets with a Speer manual, you should use caution. I'll echo the recommendation to get a chronograph if you're going to reload ammo.

The Lymans manual from the 80s had a load for a 158gr lead RN/LSWC with 18.3gr of H110/296.

H110/296 is the only powder I use for 357mag loads since my only mag load is the one I hunt with (lighter loads I just shoot 38spl stuff). In every gun/caliber I have ever tried it with it has absolutely terrible ES (like 100+ fps) unless its loaded to near to like 90-100% of case capacity.

My recommendations... get a chrono, find a start load in the 15-16gr range, and work it up until your ES get small. After that, figure out what velocity you want to hit and check to make sure extraction isn't difficult.

In a GP100 w/ a 6" barrel, I've settled on 17.0gr of H110/296 with a 158gr lead bullet RNFP or LSWC. With Starline brass its about 1400-1425fps with small ES and good accuracy. Brass almost falls out without use of the extractor. Also keep in mind what kind of brass you're using... Starline (like federal) has a much larger capacity than Winchester brass... I've noticed that the same load in Fed and Win brass will be around 40fps faster in Win brass.

Went away from 296/110 yrs ago! Waste of powder and money! Get better results with 2400. The cartridge was designed around this powder!

I like 296/110 in the 357. Much better than 2400. With 2400 to me the recoil seems sharper and add into that I have not seen any 2400 around this area in years. I can buy 296 locally if I want to but the 2400 is MIA. I have shot a lot of 2400 and would again for certain applications if I could find it but for my use 296 is better.

I have used 296 in the .357 mag but I prefer 2400. In my experence
anything less than 17.0 grs with a 158 gr bullet just doesn't seem to
burn well enough for consistancy. Some handloaders think they are
getting good loads with reduced charge weights of around 14.0 grs in
a revolver. Owning a chronograph would show them that they are
spending twice as money on powder as they need to because velocity
is less than what can be attained with 6.0-7.0 grs of several faster
powders.

Truth be told I mostly shoot low power 38 special loads in my model 27 but the hot 296 loads have been accurate but way to much muzzle flash and noise for day to day shooting at the range.

My 296/110 357 loads are full house magnums. I never reduce loads with this powder. If I want anything less I go to 231 or Blue Dot. I also shoot only 158 grain jacketed or close to it cast bullets.
I got started using Blue Dot when I belonged to a gun club that had informal silhouette shooting matches. all the old hands used 357s and 158 grain bullets using Blue Dot. It did a good job of knocking the steel down and I have sort of stuck with it ever since. I have shot a few deer and hogs using it and they expired fast and all the bullets passed through. That seemed an adequate magnum load to me.