Lyman 358429 and .357 mag brass

[omphacite]

Hello all,

I recently picked up a 4 cavity Lyman 358429 and would like to use this bullet in .357 mag with H110. The load data in the Lyman book shows that this bullet is to be crimped in front of the driving band to get an overall length that will chamber in all .357 revolvers. I have a GP100, which has a cylinder that will accommodate the 358429 crimped in the crimping groove.

I found a couple of loads on handloads.com for this combination, one at 15.0 grains (which happens to be the published max for deep seating) and the other at 16.5 grains which was said to have somewhat flattened primers but easy extraction.

Do any of you think it is worth it to try and take advantage of the extra ~0.09" of case space by loading the bullet long? 15.0 grains of H110 seems like it would be a reasonable place to start, without worrying about being downloaded too much. Any comments or suggestions are appreciated.

[Beerd]

Take a look at the TC Contender section of the Lyman manual. In it they load long and crimp in the crimp groove, but the Starting and Maximum powder charges are the exact same as the shorter overall length data.

I figure the bullet has a crimp groove so why not use it?
..

[omphacite]

Thanks. I didn't think to check the T/C loads.

[kevmc]

Crimping in the crimp groove will also be nicer to your forward driving band!!

[357Mag]

Omphacite -

Howdy !

I strongly recommend you try 14.5gr WW296 ( H110 same stuff ) and SP Magnum primers under LYMAN SWCs of 158 -172gr.
It's been a great load for me, in S & W "N"-frames of 4, 5, and 6". Also worked great in my Marlin 1894SC.


With regards,
357Mag

[MakeMineA10mm]

Hello all,

I recently picked up a 4 cavity Lyman 358429 and would like to use this bullet in .357 mag with H110. The load data in the Lyman book shows that this bullet is to be crimped in front of the driving band to get an overall length that will chamber in all .357 revolvers. I have a GP100, which has a cylinder that will accommodate the 358429 crimped in the crimping groove.

I found a couple of loads on handloads.com for this combination, one at 15.0 grains (which happens to be the published max for deep seating) and the other at 16.5 grains which was said to have somewhat flattened primers but easy extraction.

Do any of you think it is worth it to try and take advantage of the extra ~0.09" of case space by loading the bullet long? 15.0 grains of H110 seems like it would be a reasonable place to start, without worrying about being downloaded too much. Any comments or suggestions are appreciated.

Sounds like you understand the concepts, measurements, and pros and cons. I don't think you can avoid doing the load work-up yourself. If I were you, I'd start with the 14.5gr load that 357Man has had good experience with, and work up from there carefully and watch for pressure signs. Once you find them, you've gone too far (but not too bad), and you just have to back down a bit for your "max" load. You can also try measuring the case head expansion ring if you want to get detailed - it takes a really precise micrometer and some experience taking very small measurements though...

[omphacite]

Thanks for the help, folks. I worked up from 14.5 to 15.2 grains H110 with the bullet crimped in the crimp groove, today. At 15.2 I was getting in the high 1200s according to my chronograph. I'll probably stick with 15.0 grains for now, and then work up again when it warms up a little.