Subsonic .451 boolit questions

[chinaski]

Hopefully I'm in the correct forum for this question if not I apologize.

I work with a local gunsmith making smokeless muzzleloaders built mostly off Rem 700 actions, we use custom barrels (mostly Brux) and run jacketed aluminium tipped bullets from 275-325g at speeds from 2800-3100 depending on barrel length and kind of powder used. Accuracy and range has been amazing to say the least with these.

A project that I'm trying to work on now for a friend and owner of one of these rifles is a subsonic load. We've run suppressors on the rifles with good results with full power loads but I've only once messed with running our regular jacketed bullets subsonic and didn't have good results. The man that owns the rifle punctured his eardrum years back and can't take any kind of loud noise. Even the sonic crack of a suppressed full power load causes him nausea dizziness, the suppressed subsonic loads I tried didn't bother him at all.

The twist on these barrels are 1-18 or 1-20, I forget which one his rifle is. With our regular jacketed bullets we do swage them to fit the bore, we don't engrave any rifling groves, just swage them where they can be rammed down with reasonable effort. I was hoping to find something in the 350-475g weight range that would work well as a hunting bullet out to say 150yds, most of what the man will be shooting is around 100yds. I've been thinking maybe Trailboss as a powder just to give it some mass under the barrel, last loads I used were 15ish grains of IMR4198 but figured Traillboss might do better, it works well in the suppressed centerfire rifles we've used.

I guess my questions are, does this sound like it would work, if so could I just swage the cast bullets as we do with the jacketed ones or would I need to engrave rifling, is the barrel twist that much of an issue or is that enough to stabilize some of the heavier cast projectiles?

I ran across a man on this forum once before that had a good reputation for selling bullets and a website but I can't seem to find him now. I was hoping to be able to order from him and if someone could point me in his direction I would appreciate it.

Thanks in advance for any help or suggestions.

[JonB_in_Glencoe]

chinaski,
Welcome to the forum.

What an interesting project. While I don't powder coat boolits, that is what I'd recommend using on a lead bullet (cast or swaged) in a gun with a suppressor. You will likely want a heeled boolit design with lube grooves, where the front and middle driving bands are sized to groove diameter.

Trailboss's bulkiness is designed to take up extra space in a cartridge, and I can't imagine it being of any special value in a ML, it's likely a detriment, because if it gets crushed during boolit seating, that'll change it's burn characteristics. As for powder, I would use Pyrodex. But, if you feel the need to use something that isn't BP or a BP substitute, then you could investigate Unique...maybe send an email to Alliant to confirm that it would be safe for your application.

[mehavey]

This is a muzzleloader, correct?
I assume a ramrod is used?

If so, I would suggest that TrailBoss not be used as it doesn't take kindly to any kind of compression.
And with the kind of bullet/barrel/loading technique I envision, you can't control that factor real well.

I was also going to suggest Unique, But since you are seating the bullet directly on the powder instead of in a case w/ controlled airspace, that's going to take some work-up trial & error with a good chronograph until you find the right combo.

I might take a look at QuickLoad later for a starting point with a classic Gould 330gr HP, seating for zero airspace in a Schofield case.
But any bullet you find/use will have to be cast SOFT (BN8-ish/30-1) or so at those pressures/velocities.

BREAK BREAK... just to give you a QL calibration on what seating the bullet on the powder does...

330 Gould sized to 451.
6gr Unique
Seated to hit powder in Schofield Case
34,000psi/1,000fps out of a 20" barrel (and at those pressures, go Lyman #2)

You really do need to carefully work this up w/ QL and a chronograph.

[RU shooter]

For this kind of application I'd be looking at using reduced loads of real black powder or PB substitute powders

[chinaski]

Good call on the Trailboss, I wasn't thinking about the compression, the only low powder loads we've ever messed with has been with IMR 4198. We may take a look at using a BP substitute though one of the nice things about the smokless has been well, no smoke, coupled with the cleaning ease of smokeless we'd like to stay with that.

Seems the most overwhelming part of all this is bullet selection and sourcing, we aren't set up to do any casting and don't have any experience other than reading the old Pope articles and the Mann book, both of those served to let me know I really don't know squat about making cast bullets.

[truckjohn]

Welcome!

Nearly 100% of 45acp bullet designs are subsonic. Most of these are used regularly for target shooting.

I would recommend starting with any one of the standard 45acp cast bullets as they are all designed around subsonic performance.

Second is a minnie ball design. The designs are worked out and generally well behaved.