450Bushmaster.net

Well it sounds like shooting TrailBoss is like using gold dust for powder.....I have 2-2 lbs and about 1/2 of a 2 lb it should keep me in powder for a little while.....don't do Cowboy Shooting any more so should last me a little while....
Several week ago I saw several 8 oz. containers of TrailBoss it was $34.95 so all I did was look....

It's a great powder for Cowboy shooting don't know what those guys are using to take its place....other than some of the shotgun trap=skeet powders and I haven't see much of those around....

I posted this as a question a couple days ago but have reached my own answer.  

First caveat!  Take this information and use it at YOUR OWN RISK!.  I have been called a moron by a lot of people dumber than anyone here.  Your Mileage may vary.  Taxes, license plates and dealer prep are extra.  Should you develop an erection lasting longer than four hours seek immediate medical attention.

First off my calculations.
https://i.imgur.com/UZotIxm.jpg

I started by looking at the 454 Casull which I think somewhat close to the 450 BM as far as a pistol length barrel goes.  From the top, determining gain in feet per second per grain of powder in this cartridges range.  Change in velocity versus change in charge weight.
54.8 feet per second per grain of powder in THIS CARTRIDGES RANGE.  I would have to lessen the load by 4.98 grains to go subsonic with the other things remaining the same.

Next I interpolate the relative energy between VV 3N37 (and not shown) VV3n38.  3n37 has about about 1.47 times the energy estimated IN THIS CARTRIDGE, IN THIS RANGE OF LOADING!   So I need to scale down my load to 67.8% of the H4227 and Lil Gun.  The last step is calculating how much VV 3N37 I need and I come up with.  13.9 Grains. I'm going to start with 13.3.


Second, Here's the setup.
https://i.imgur.com/HI8C2aq.jpg

10.5 inch 450 BM on an AR platform.  Magnetospeed Chrono on a Caldwell Sled.  50 yard target.
Chrono results;  3N37;  1010, 1071, ERROR.  AVE = 1040.5.  We're in the ball park.
3N38;  1000, ERROR,ERROR.  AVE = 1000.
I have a screw loose.   ...in my Magnetospeed!

Third, Results.
50 yards.  Three feet of snow.  Took half a dozen trips with the snow shoes on to pank down the snow so I could see the target burm.
https://i.imgur.com/NYIgugK.jpg

https://i.imgur.com/HMXxhHz.jpg

So there you have it.  I went from 13.3 3N37 up to 13.8 3N38.  Placed some white paper tablecloth stuff in front of the bench and saw no detectable un burnt powder.   The action did not cycle and had to hand eject each case.  I think (hope) the suppressor will add a little more back pressure.  Running the lightest buffer I could find now.  May try trimming some coils of the buffer spring or lighten the bolt carrier.  Stay tuned for further revolting developments.

It’s just my personal opinion that if I was going to seek out those types of velocity’s, I was just build an A.R. 15 chambered for 45 ACP.

What would you use for magazines?

With a lot of powders you no going to get it to function a semi-auto shooting sub-sonic....

Myself when shooting sub-sonic I use a bolt action or single shot....first it going to be quieter firing a bullet in a bolt or single shot....second the action will alway work no playing around trying to get the right load.....I want it sub-sonic and also quiet...not all powders are the same amount of quiet when burnt....
I have shot several bucks under 50 yards that just stood there looking around after being shot with a bolt action 450 BM then fall over kicking....all shot with a Cutting Edge Bullet 240 gr handgun Raptor with a tip added and TrailBoss pushing the bullet...
I've shot numerous crows, squirrels and varmints around the house and the wife doesn't even hear a shot....a couple of times has asked what that funny smell when I shoot out the back window....