40-70 SS bullet choice

[cat1870]

Hello:
I have an 1874 40-70 SS with a 30", 1:18 twist barrel. Using BP what would your choice of cast bullet mold be?
I'm currently using a BACO 409420M4 mold (length of bullet 1.442")with fair success. One day it will shoot 1-2 MOA ay 265 yds and the next day all over the paper using the same load.
I'm wondering if a shorter bullet might be in order.
Suggestions?

Thanks

Cat

[gunlaker]

That bullet would be better in a 1:14 twist rifle. would have a look at the Saeco #740. Buffalo Arms seems to be selling Saeco molds at a discount at the moment. I ordered a backup saeco #740 just the other day

I should add that I shoot a couple of Shiloh 40-65's, but the chamber front end is the same so should like the same bullets.

Chris.

[J.B.]

At that length it's 'getting up there' for length in 40 cal designs. I've been running a reduce band bullet @ 1.3" in our 40/ 70 straight and it seems to be a happy marriage..though we have a 1/16" twist. I'd be guessing that when conditions are forgiving the 1.442" is working o.k. but over an extended distance or when the winds play up ( and dont they always ) all bets are off. With a 1/18" I'd be looking under 1.3 and probably closer to 1.25" or so. Depending on your load now, if you pick a design that allows seating out a tad, you may pick up some powder volume and hence velocity increase. This 'can' help ( not always ) but its an aid, rather than a solution. hth.
J.B.

[steveu834]

Cat, I had a 40-50sbn and have a 40-90sbn both have 18” twists. The best bullet I have shot in them is the Saeco 640. It is about 1.2” in length which is close to the max for that twist. I have in the past tried other longer bullets and had the same result you are getting. There are lots of posts in the forums about bullet length and barrel twist. Distant Thunder has a good one on this subject.
Cheers,
Steve

[desert deuce]

Ditto the Saeco #640 in an original Hepburn in 40-70

[desert deuce]

What seemed odd at the time was the Hepburn in 40-70 seemed finnicky yet the Ballard Pacific in 40-63 did not.