A friend casted a batch of 158gr SWC with gas checks for me. I have never used gas checked bullets before and wonder if I can use the same load as a jacketed bullet. My JHP/JSP pet load is 16gr of W296 using CCI-550. Is this a good start?

It is going to depend on how hard the cast bullets are.....if they are hard, then generally you can drive them as you would a comparable weight jacketed bullet.....I cast SWC's plain base bullets out of straight wheel weights and haven driven them with 15 gr. of 2400.....my normal load is 13.5 of 2400 as it does anything I ask of it. I have harvested several deer with this load from a 6" M-28....if it was me, I would throttle back a bit from a max load, see how they shoot and how your bore looks as far as leading goes....then proceed.

Thanks. The max load for jacketed is 16.6gr of W296 so I still have some margin.

Just my 2¢
I have never had success with 29 or H110 in the .357, although it is my powder of choice with the .44 Mag.
I have loaded over 100 different loads in the .357 in the last 35 years, and by different I mean the gamut.....296, H110, 2400, Unique, AA9, AA7, AA5, 7625, and more....
The winner by clear margin is 2400 in 4 different guns from a RM to a PC gun with 5" barrel.
14-14.5gr. 2400, Federal small pistol magnum primer, 124jhp up to 160gr Keith bullet with gas check. Accuracy is incredible.
Here's the thing. If you use a proper GasCheck (GC), the cast hardness is not nearly as important as would be if shot without GC. I use BN 15 for mine, and find no leading. I love the Keith bullet with 14gr. try it.
Terry

I have loaded 15.0 grains of 2400 behind a Lyman 358156 with GC for several years for use in my 27s and 28s. Excellent accuracy. I use a different load for my K frame magnums.

Ditto what 27Man said! Gary

Agreed. The 358156 in straight wheelweights is my magnum load. Use 14 grains 2400, standard primer. Shot out of three different security and service sixes, great accuracy, hardly any leading ever. Tried going a little hotter, groups opened up. Probably just my old hands and ears not liking the difference! Doubt it was the guns!

I talked to my buddy that casted the bullets and recommended 15.5grs of W296 for the gas checks. I went with that.

This is for my Ruger Blackhawk and GP100's.

One of my all time favorite loads for my .357 for target shooting is 162 gr LCSWC (straight wheel weight) with 15 gr WW296 powder. I shot with and without gas check and didn't seem to make much difference in accuracy or leading of the barrel. The 162 grain LCSWC bullet is an RCBS mold w/gas check .

I also loaded 12.5 gr of 2400 powder behind the same bullet and it is accurate, but seemed to always be dirtier.

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James

If you are going for the same velocity, you can use a bit less powder going from jacketed to gas checked lead since lead has less resistance than copper and will run faster with same powder loads. I have used 16 gr. 296/550 primer with 358156GC with no leading. 14.5 gr of 2400/500 primer does 1336fps from my 4" 686. Love that bullet.