Ever since suppressors became legal here in Iowa, I've been doing alot of research on them. And when I saw that SilencerCo came out with the Hybrid (rated for 16" barrels with .45-70), it got the gears to turning.

So what's bouncing around in my head are the possibilities of using subsonic .45-70 loads with one of these suppressors. I've also been wondering what kind of twist it would take to stabilize really heavy bullets. I've even considered going as far as trimming the brass back to be able to load some sort of custom 600+ grain bullet that is basically a spitzer with a blunt nose to accommodate being in a tubular magazine. Of course, these would have to be coated bullets (something similar to what Alexander Arms is doing with the .300 BLK), solid gliding metal, or some sort of JSP.

Basically, a whisper version of the .45-70. A really heavy bullet (the heavier the better, to a point) that is subsonic.

Thoughts?

Are lead bullets not compatable with cans? I would think a  45/70 subsonic would be mild and running cool and clean
At those speeds lead is what you want , Why do you want a spitzer? and coated ? At the trapdoor level of loading the standard 405 grain bullet is subsonic with most powders at starting loads and this is with a 24" or greater barrel. You would likely bump those starting loads in your shorter barrel.
Is your use hunting? 45/70 won't expand but .459 is a lot like what a .30 caliber hunting bullet hopes to expand to . The issue with hunting with any subsonic bullet is the rainbow trajectory , a good hunter needs to estimate or measure range well and know the trajectory to get his hits . The thing about a 45/70 405gr (or larger !) is that it more or less defines penetration unless you are hunting something larger than a Bison .
Lyman has a "Cast Bullet Handbook" that gives lots of loads and the cowboy guys have rehashed that again.. My older lyman book shows a 1:22 twist for the original springfield and 1:18 for their 24" test barrel .

Most of the cast bullet outfits offer a 405 gr 45/70 bullet which was the original government "light" load for carbines with the "normal" load being 500 I believe.

I know old school cast bullets but cans are out of my range of normal operation

Most suppressor manufacturers recommend not using cast bullets due to fouling, even with subsonic loads, and most rifle cans can't be taken apart to clean. So I don't want to take the chance.

And I'm not looking to hunt with it. What I'm envisioning is short to medium range barrier penetration, ect, hence the idea of using heavier bullets. Like I said, I'm thinking more along the lines of the whisper wildcats, or .300 BLK. But something bigger and much heavier that can run in a levergun.

I realize that this is outside the box for what most folks think of in regards to leverguns. But sitting behind of the wheel of a truck all day, a guy can come up with some weird ideas.

And the reasoning behind the spitzer shape is to reduce the bearing surface of the bullet.

This page might be of interest to you...LINK

And this one for custom molds, play with the gadget and design your own...LINK

You ain't the only one with this thought.

ETA: The use of powder-coated bullets will prevent almost all of the fouling associated with cast lead bullets.

Thanks for the links. I'll have to read up and do some tinkering when I get some more time.

Limited cast bullets are not going to be an issue in a suppressor. A gas check should help leading . . Depending on the suppressor you may be limited by other issues . I think Bowers says 45-70 but only at 1,000 fps or less .I think pressure is a issue there . How much of a barrier are you going to shoot that the 100 grain difference between 4 and 500 makes a difference . I shoot a lot of hard cast 400's from my 45-70 with great results at 1600 fps . They can be loaded hotter . The 400 will knock a big hole in things as it sits . I still want to load some 500's

Do your self a favor and pony up the $150 to get a copy of Quickload. It's an amazing software package.  It'll allow you to test various bullet powder combinations not found in reloading manuals.  It's particularly helpful in developing subsonic loads.

A HiTek coated boolit shouldn't lead < 1600fps, and a PC boolit will handle faster speeds.  This assumes that both coatings are properly cured.  I've tried both coatings on a 535gr Postell in my repro Sharps, but it prefers that boolit with lube.   I would not run lubed boolits through a can.  Coated should be fine though.

If your willing to get it dirty , a 405 gr 1-30 tin to lead bullet , a .45 cal wonder wad and 55gr of black powder will keep it subsonic

No, I'm wanting to push the most weight I can while staying within SAAMI pressure limits.

My one load book shows 500 jacketed bullets at a starting load that is 1150 fps . It would seem possible to get that down a little