375 Win cast bullets
 

Question: The specs for my mold I got for the 375 Win (and 38-55) throws a .379" bullet. I'm going to be using an alloy with a BHN about 18. Specs on the 375 list a .376" bullet while the 38-55 list a bullet diameter of .377". Will I need to size them down to .377"or .376" prior to loading. Bullets will be powder coated and not lubed.
I think I just answered my own question. I went down and slugged my bore and it measures .376" I believe I will need to size them down some. I'm thinking .377"! What say you?

obviously you should start testing your reloads with a slightly reduced powder charge,
Id start 3-4 grains lower than you think the manual shows just to be safe and test,
and load 5, cartridges, and check before stepping up one grain at a time, for the next 5 test cartridges,
but its been my experience the marginally larger cast bullet provides no problem
with pressure or accuracy,
but ID point out I use a moly/bees wax , bullet lube and gas check design not powder coated projectiles
the difference should be minor/marginal but test
most cast bullet loads are operating at far lower pressure than similar jacketed bullet loads produce.

http://garage.grumpysperformance.com...35/#post-84993

HC I did some searching and after slugging my barrel I decided to buy a Lee push thru sizing die @ .377". As far as loading I rarely ever produce "hot" loads no matter what I shoot. I always get much better accuracy with less than maximum charges.
With my bore diameter of .376" and using a bullet of .377" I should get pretty darn good accuracy. Probably as well if not better than jacketed bullets.
Lee has designed a neat new set up for sizing bullets. Instead of buying a Classic Sizer Kit for something like $30 you can now buy a Breech Lock Bullet Sizer which is basically the unit that screws into your press for $16 then you can buy different size punches that you put into it at $15 a piece. Man I wish they would have done this a long time ago. It would have saved me a bunch of money.

youll certainly get a small bit more consistency in the bullet size vs using as cast diam. and thats never a bad idea.
as an example ,in my 458 win, Remington bolt action, Id tested as cast .460 diameter bullets lubed vs ..459 sized and lubed 405 grain bullets

over 55 grains of IMR 3031, I got no measurable difference in 100 yard bench rest accuracy, everything shot into about a consistent 2" 3 shot group.
my friends ruger #1 had the same results, he used that ammo for local hog and deer hunts with good results

Well the 375 bullets came out really nice. I cast almost 100 last night and measured a sample of them and they are right at .3785" - .379". After sorting them for flaws I powder coated them with Eastwood's Ford blue powder. I also weighted a pretty good sample of them and every one I weighted on my digital scale was between 247.3 - 248.4 grains. That's as consistent as some jacketed bullets I sample weighed. There now all set an ready for sizing once I get the .377" sizing die I have on order. Then to the loading bench where I have 50 cases ready to go.

well it looks like your well on the way toward having a decent cast bullet...
now what powders?
keep in mind some twist rates rifling depths etc.
seem to prefer slower burn rates or some faster burn rates and higher pressure levels
a bit of testing should help you decide, generally mid range to moderately fast burn rates like RL7, RL12, IMR 3031, IMR 4064 work ok

I only have one manual that list cast bullet loads for the 375 win and thats the Lyman manual. From what I'm seeing I'm going to yry some with IMR3031 and some with H4198. I can get better velocity withthe 4198 but I prefer accuracy over velocity.

let us know what you see as results and the loads used please

They look great. Can't wait to try them out.

well? what results?? any issues??

Initial shooting shows promise. With the short barreled 94 Big Bore and open sight just throwing a load together I shot a 5 shot group about 2" or a bit less @ 50 yards. Problem is that they group about 6" below the factory loads and I don't have enough sight adjustment. I got a lower front bead sight to install and will do that once my supply of factory jacketed ammo is exhausted. Or I just might sell the factory stuff and shoot these. I'm happy with them.

a different powder charge and a change of powder/propellent and that change in pressure curve,
is very likely to change the bullet impact point in relation to the rifle sights,
and frequently group tightness.
don't be afraid to experiment,
powders like
imr 4064.
imr 3031,
RL7, RL12
IMR 4198,
WW748,
imr 4895
can be used

Yep. I've been at this reloading game for over 55 years. Even different powders with the same MV can give different results just because of their burn rates. Next batch is going to be IMR3031.
In fact, this afternoon I may just cast some more .375s and some .458s for my 45-70s

RE#7 or IMR 3031 is all you'll need. I run IMR 3031/32gr under a 268gr GC in a re-bore Marlin 336 /now 38-55 and am getting 1 1/4" at 100 yards with a 4 X Leupold mounted.