Have a friend with a 358 Towsley UtraMag, who wants to load his with "heavy" bullets, 275s and 300s, but no load data (at all, let alone heavy bullets) he got some data from Towsley, but for bullets only to 250 grains.

Anyone have any data, please let us know.

Try looking for load information for the 360 Imperial Magnum; its an improved 404 Jeffery case necked down to .358 caliber. The case capacity should be close to your 358 TUM cartridge.

Thanks Jim;
This was posted for me.

The beginning load I've started with was: 250gr, 90gr 7828, 15 shot avg was 2884fps. Towsley had a bit more powder and 3100fps in a 24", my rifle is 26". He feels I should easily get 3200fps with the 250's.

I haven't gotten back to it since that day. I do have loads with the same bullet up to 100gr.

That's as far as I've gotten so far mostly due to health issues.

The proper names for this is: .358UMT, or .358/300U/m

Thanks again,
George

Hi George,

Does your rifle handle 3.6" or 3.8" COAL loading data?

I checked "AmmoGuide Interactive" today for a similar cartridge to your .358 UMT and located the .358 Ultra (a .358/.300 RUM cartridge, 3.6" COAL) created by Michael458.

Listed are multiple bullet weight loadings by Michael (24" barrel CRF M70 Winchester) including loadings for the 280gr Swift and the 310gr Woodleigh.

Hopefully that information will help you in your endeavor.