Using jacketed bullets with cast data in .375 Ruger?

Since this is a handloading question I've it moved it here to Handloading and Reloading.

In general, NO. Lead bullets have much lower engraving pressures and are slipperier (lower coefficient of friction). Pressures WILL build to higher levels when you substitute a jacketed bullet

Now that the PC answer is out of the way... With fast RIFLE powders, you shouldn't have a problem. If the data was developed for cast by a reputable lab, then they should have stopped at a level that will be far below 60,000 psi due to cast not working well above about 2500fps. This number is flexible, and someone surely has used an alloy/heat treat or the perfect lube for the situation and gone above 2500 fps without leading. Also, high pressures with cast will blow the base and cause gas cutting which results in leading. So again, the LAB data for cast use will normally stop at a mild pressure level and should tell you if it was taken about this just to explore how the powder behaves. I'd respect the max limit regardless unless you have some strain gauges or internal ballistic software to aid you.

Pistol and shotgun powders demand much more respect. The slowest are faster than the quickest rifle powders. I've found Aliant 2400 to behave similarly to IMR 4759 in '06 and 308 cases .24 to .35 bore. I had older published cast data with some .30-06 M2 FMJ's and 130gn .270's (jacketed) included that ran up to 50,000 CUP. From this info, I took 85% of the 35,000 CUP cast loads and called it good for similar weight jacketed.

See how we're going? Research Lyman say for some cast 375 Rugar data with Rel #7. Due to reasons other than outright MAX allowable strain on your rifle, there should be enough safety margin for a switch from cast to jacketed for that 235gn Speer Hotcore.

Doing what you are thinking about doing is not a good idea IMO. Most powders do not react well to being downloaded. You need more powder to push a jacketed bullet than a lead bullet so there is the possibility of sticking a bullet in the barrel. That is not a big problem but if you don't realize it happened the next trigger pull will get very interesting very quickly.

I know you said you don't yet have a mold but why not buy a few lead bullets to hold you over?

Another option is to use H4895 for reduced loads. Hodgdon has tested this powder and supplied data for us. I know you want to use up your RL-7 but using H4895 is safe when used as tested. Looking at the Hodgdon 375 Ruger data shows they do list H4895 data with a 235gr bullet and it looks like the Hodgdon 60% formula will get you right where you want to be.
http://www.hodgdon.com/PDF/H4895 Reduced Rifle Loads.pdf

Ruger44mag said:

Thanks Artee and Archangel. That's some good info. I probably wont use that powder for that and I will just save those Hotcores for another time. Any recommendations for good cast .375 bullets?

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I think these are for the 38-55 WCF @.379" but they are probably just fine for the .375 Ruger too. I might be wrong so check before you decide.
http://www.missouribullet.com/details.php?prodId=113&category=6&secondary=&keywords=
The people at Missouri Bullets are good people to deal with and it's a stand-up company.

Ruger44mag said:

Thanks Arch!

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You're welcome, glad I could help...

I shoot ALOT of reduced load 375 H&H using 225 gr jacketed projectiles and SR-4759 powder.

I load them to 375 Win specs.