Newby BP Question on patched round balls.
 

I have an optima magnum in-line rifle 1:24 twist. I tried for the first time
yesterday shooting patched round balls out of it, the rifle is .500 cal and the
balls were .490 I was using prelubed patches. I was all over the target at 50
yds. This rifle was giving me sub 2" groups last time I had it out with
saboted .45 bullets. I tried both Shockeys powder and Hodgdon's Pyrodex
RS, the Pyrodex was much cleaner but no more accurate, I was shooting 150
grains of powder.

TIA for any insight.

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Your rifle was not designed to shoot patched round balls. In fact CVA recommends that it should not be done with a gun with a 1 in 24 twist. If you want to shoot round ball get a rifle with a 1 in 48 or 1 in 66 twist.

1 turn in 66" rifling will do best with round ball,
1 turn in 48" round ball, ball-ets, short conical bullet and saboted pistol bullet,
1 turn in 28" conical bullet and saboted bullet.

+1 on what Walley said.
F.K.

The patched round balls were seriously "overstabilized" or spinning too fast with that rifling. You're stuck with saboted bullets or conicals with that barrel.

Like the others have said...too fast of twist for that load you're trying. If you want to try patched roundballs out of that rifle drop your powder charge way, way down to about 70 grs. and see what happens...might work, might not. I had an Optima given to me a few years back...wasn't ever gonna shoot it but thought it might make a rabbit/squirrel gun with head shots. Shoots good with 35 grs. of 2f Goex and patched roundball. Far as I ever got with it though.

Thanks for all the replies, that does explain everything I witnessed yesterday.

Follow up question, a friend gave me a Lee mold for black powder
as I cast bullets for my .357 Mag and .45 acp. Now I do know that
you should use pure lead for BP. Of which I have accumulated some
now.

Part number: 90472 Description: MOLD_500-360-M
Improved Minie, Traditional Design
Lee Precision, Inc. Reloading Tools and Equipment: Black Powder Molds

My question is will this work in my Optima Rifle.

Just be aware that you can't drive them too fast or you'll "blow the skirt" or create excessive leading.

I have a chronograph, so what would be too fast and what would you recommend for a starting charge 70 grains or 100 ish...

I would start with 60 grs. and go from there.