What do you guys think of loading Rainier .357 plated FP over 6.0 grains of 231 in magnum cases for a midrange load? I loaded some samples and they seemed fine. No chronograph. My table shows a max charge of 6.7 grains with a 158 gr. lead bullet gives 1275 fps. I'm using a standard primer with taper crimp. OAL 1.580. Getting ready to start cranking 'em out and wanted some opinions before I commit. I've always loaded jacketed and I'm trying to save a little money. Already have plenty of 231 on hand, that's why I want to use it. Thanks in advance.

I would only load a few of them at first. That's at levels you may shear plating off the bullet.

That makes me a little nervous and I likely wouldn't load my plated Xtreme 158's (w/cannelure) with that charge, but I'm also very new to reloading. I've been using lead load data and have shot a handful of the plated 158's with 5.0gr of W231. I was also using CCI small magnum primers and a fairly mild crimp to not damage the plating. They are a mild load and shot fine.

Howdy:
Don't know about Rainier plated bullets; I use plenty of Berry's plated 125 gr flat points in .38 special cases with 231, with a moderate crimp over the ogive ( bullet seated a BIT deep) . I find that 4.5 gr is REALLY snappy , though safe in MY .357s, while giving more accuracy than I am accustomed to. Remember, your experience may differ, safe in mine may not be safe in yours ( heck, we may not even use the same brand or model of powder scale! ), so it is up to you to determine safety and suitability.

My experience with Rainier, Berrys and Xtreme has been that they are best kept below 1100 fps. (That this is very close to the speed of sound may be a coincidence) Your load may exceed that. Try firing a few at a piece of cardboard. If you see a hole you're probably in good shape. If you see gray flecks that look like lead or extra ragged holes, the plating has failed.

I have pushed 158 gr Xtreme SWC as high 1700 fps but I don't recommend it as a regular practice.

Here's how you can tell you're gone too hot with plated bullets.
Load a few and carefully fire off a rest for groups at 15 to 25 yards.
If the groups are nice and tight, as good as any you normally shoot, the plating is holding up. If your groups are turning to patterns, that's a sign the plating is giving way in thin spots.
I've found that it varies from gun to gun (and powder to powder) how far you can push it.

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Science plus Art

I've never used plated bullets before . In .38 or .357 how do you not get bullet jump without a cannelure to crimp into ?

I don't crimp plated bullets very much, more like you do a .45ACP, just past straight.
The sized case provides most of the grip, and the plated bullets are not made for magnum loads anyway. I've shot many tens of thousands of them in .38 for IDPA with no bullet problems. Overcrimp or overload them, and you get troubles plenty.

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Science plus Art

What was that .38 load you used for IDPA ?

Was using .38 Federal plated cases holding 158gr Berry over 4.5 HP38 until IDPA dropped SSR PF to 105. Now I load 4.3 HP38 for ICORE ( min PF 120) and also shoot them for IDPA. If I were going to IDPA Nationals I suppose I'd drop it a bit more--or not. It's a very comfortable load in the model 66 I'm running now.

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Science plus Art

I'll try parabarbarian and okfc05's advice. Thanks guys. I also loaded some at 5.0 and 5.5 grains, but they seemed like .22's out of my 4" L frames. Think I'll go back and revisit those levels and do these tests on them as well. Guess I should just spring for a chronograph.