Henry 45 Colt cast bullet performance question

[Bill2905]

I own a Henry Big Boy Steel 45 Colt lever gun with 20 inch barrel. It is a 16 twist barrel. I shoot two different bullets, a Laser Cast 0.452 250 gr RNFP and the Nosler 0.451 250 gr JHP. Both are usually loaded atop 8.0 grains Unique. The Nosler load consistently delivers 4” groups at 50 yards using open sights. The Laser Cast load performs much more poorly and consistently delivers 8”-10” groups. Both bullets punch clean round holes in the target.

I would like to improve cast bullet performance in this rifle to take advantage of the lower cost. I know that I need to try a different cast bullet but am not sure where to start. Is there anything about the better performance of the 0.451” Nosler JHP that would point me in a certain direction? The diameter difference is obvious but I'm not sure that means as much when comparing cast bullets vs jacketed ones.

[Fuj']

With 20 inches of barrel, I'd try a different powder first. 2400
would be on my short list. And if your asking about bullet diameters,
best to have that barrel slugged.

[Bill2905]

With 20 inches of barrel, I'd try a different powder first. 2400
would be on my short list. And if your asking about bullet diameters,
best to have that barrel slugged.

Thanks for the info Fuj. I may try slugging the barrel. What would you recommend that I use for the slug? I read all kinds of suggestions from round balls to soft bullets, to egg sinkers.

[Fuj']

I going to recommend a smith do it and while it's there have the
crown checked and touched up. That could be your problem with
the group sizes you posted up.....

[DocCoffeeKevin]

Slug with anything you have that is as close to pure lead as you have, one reason a muzzleloader round ball is often recommended. It has to be soft enough to upset to full groove diameter as you push it through the bore. Get a 7/16 HARDWOOD dowel, cut a couple short lengths to get started, think Muzzleloader "Ball Starter". I would guess you want a bullet .0005-.001 larger than groove diameter.

Actually your biggest problem may be the Laser Cast bullet. Seems to me like they are "Hard Cast" maybe as high as 20-22 BHN and that Unique load will be much happier I would guess with something in the 10-12 BHN range, certainly not more than 15, Unless your are trying to make your .45 Colt into a .44 Mag. "Hard Cast" bullets often strip in the rifling, can't get a grip.

I shoot a Henry Big Boy in .41 Mag, similar load, 6-6.5 Unique with a cast. It will hold around an inch at 50 yards.

Just my opinion/experience. Maybe worth what it cost ya.
Kevin