I'm loading for a new-to-me cartridge, those of you that
know me will know it but thought it would generate
more unbiased speculation to leave it un-named at first -

Anyway, case capacity is around 84 gr of H20,
100 years plus old origins, no belt, no magnum in it's name -
looong, skinny case with almost no neck, big bullet 250 gr
and up. Traditionally uses LR primers, but I'm shooting it
in a modern rifle and exploring the limits of what it can do.
I'm lighting off as much as 73 gr of Reloder 17, 70 gr of
IMR 4007SSC with one bullet. No pressure problems, but
at near full case charges, I'm getting a little vertical
stringing of the shots. Not terrible, from round 1.5" groups
to 1" x 3", vertically stringing. Doesn't surprise me,
could just be the rifle (I shimmed the barrel up off the
factory pressure point at tip of forend but haven't got
to try it yet) But I'm wondering what some Federal 215's
would do for it, and if anybody else had done similar?
Not slow powders, but a fair amount, and some of it is a
long way from the primer - the long, skinny case.
Probably going to try it anyway, but thought I'd ask.

The traditional rule of thumb is use mag primers over 60 grains. Sometimes that's best, sometimes it isn't, you should experiment with your gun to see which produces the most consistent velocity.

Ok, thank you. I didn't know that. I'll try them, least
soon as I can get my hands on some. Figure to back off
10 percent and ease back up, watching groups (and pressure)

Some LR primers are hotter than others. IIRC I read somewhere a few years back that Winchester was the hottest LR. I would experiment with Winchester LR and Fed 215. I have used WLR's in full-power .375 H&H loads (79 gr H4350/300 gr. RN) and couldn't tell much difference in performance as compared to Fed 215. YMMV.

KInda sounds like you're loading for a 9.3x74R, or something similar? I generally use F215's in mine, particularly if I'm burning ball powder. Which I use a lot.

Jeff

Edit-
We have a winner, ha. Ak I was posting this at the
same time as you I guess. Thanks, def gonna try the 215's-

Thank you. My cartridge is as I understand it, a
slightly less powerful contemporary
of the big H&H, from other side of the channel - 9.3x74R
No, I'm not abusing a fine double or drilling with these
loads

I load for it, in both a modern gun(Ruger No.1) as well as a drilling. In the drilling, I keep my 286gr loads in the 2250fps range. In the No.1, I'm focusing on a 250gr TSX, and ballistics on par with the 9.3x62 and x64.

Jeff

Ruger for me, want a double someday but it'll have to wait.
Have you done anything far as shimming,tinkering with the
forend, or has yours been too good to mess with? I've shot
real decent groups, but just can't help tinkering long as it's
stuff I can un-do later...

I don't think it matters that much. Some brands LRs are hotter than the LR mags of other brands. Just work up loads for whatever primers you are using.

Haven't touched the forend, as it has shot well as is. The only change I made, was putting in a Kepplinger trigger, which I'm very pleased with.

Jeff

Got somebody bringing me a brick of Fed 215's
from gun shop in next town up the road -
All they had was Gold Medal "match" more $ but
I'm doing this hoping for more accuracy anyway, so
In today's situation just thankful I can get any kind of
primers really.