Hi guys the mould design in this screen shot is one I am considering for my .375 Winchester Big Bore!

http://castboolits.gunloads.co...=105532&d=1400668413

What do you think, good and bad points?

On a side note someone told me not to use Lyman 2 in bigger calibre rifles (only softer alloys), why?

Andy, the link does not work.

I tried to edit the link but since I'm not a THR member it won't let me access the page.

Hope this helps...

I don't know that this design is different enough from the Lee plain based 38-55 mild to warrent paying for a custom mold. Of course, knowing it is from Mountain Molds you will be assured it will be a great mold and will cast to spec...something that can't always be assumed about a $20 Lee offering.

my 375 win likes 379 diameter you'll wanna spec 380 and size down.
or spec 379+.0015 with ww+ tin alloy.

A lot of casters heat treat their WW bullets to get the hardness needed without using so much tin as used in Lyman #2. They drop the bullet out of the mold into water. If the alloy needs arsenic to get the hardness required they add a tiny bit of magnum bird shot.

Have you looked at the articles on the Los Angeles Silhouette Club site? They cover about all the alloy questions there.

I use 20-1 alloy in large bore rifles because I do not shoot at very high velocities. Many of the large bore guys shoot black powder and use the soft alloys so the bullet will bump up to fit the bore.

The software calls for a 17" twist.
The .375 has a 12" twist and will handle much heavier bullets. I am not sure how well the .375 does at higher velocities with that fast twist. The typical .38-55 has an 18" twist and might work better with your bullet.

Check out the data on the gmdr web site.
For the 375 it seems that accuracy drops off quite a bit above 1000 to 1000 FPS.

Your bullet mold is like the other poster - It is very much like some of the Lyman molds.
I have a Marlin 375 and it shoots ok with jacketed but I am not so sure how it would do with cast bullets.
I like the .38-55 better because of the slower twist. A .375 with a slower twist would also be good but then I only shoot targets with those rounds.
If your rifle is a repeater it will be limited to the Lyman 250 to 270 grain types of designs.
If you shoot a single shot you can use a much heavier bullet that might shoot better in the faster twist.


GMDR lever gun data

quote:

Originally posted by andym79:
Hi guys the mould design in this screen shot is one I am considering for my .375 Winchester Big Bore!

http://castboolits.gunloads.co...=105532&d=1400668413

What do you think, good and bad points?

On a side note someone told me not to use Lyman 2 in bigger calibre rifles (only softer alloys), why?