driftrider

This brings up the question in my mind "what about the transsonic region and it's effect on a muzzleloader bullet?" With high powered rifles, the maximum effective range of the rifle is the distance at which the bullet enters the transsonic region (about mach 1.2). As it gets close to the speed of sound in the air it's traveling through, the dynamic stability of the bullet goes wacky and the bullet usually starts to tumble by the time reaches mach 1, which completely wrecks the accuracy beyond that point. Because of the relatively high BC and high MV of rifle bullets, this range is usually well beyond 800 yards. But the much slower launch of the muzzleloader bullet, and the relatively poor BC, means that it'll enter the transsonic region within a few hundred yards.

I ran the numbers through JBM to see, and a 450 grain .458cal Barnes Banded solid, which is similar to the shape of a lead .45cal conical you'd be shooting from a ML, launched at a velocity of 1500 fps (which is pretty reasonable for BP velocity for such a heavy bullet), would cross the sound barrier at just 293 yards. It enters the transsonic region (mach 1.2) at just 100 yards. Now, I know full well that people shoot a lot farther than that, but I wonder if to do so they have to launch the bullet subsonic to avoid the transsonic stability issue.

Ponders...

Mike

BIG.PAUL

Wow thats something I never considered. I guess a person always thinks of a muzzy as a slow shooter.

lemoyne

driftrider
If you have the software for that would you figure a .269 BC at 2350 FPS?
That is my 50/40 200gr SW load with Blackhorn. Lee

Semisane

Lee, here's one chart with a zero at 500 yards (+42 inches at 300 yards). It looks like the bullet enters the transsonic zone of 1230/1340 fps at around the 400 yard mark. Notice the 2+ feet of wind drift with a 5 mph crosswind.

driftrider

I'll do you one better and give you the link to the website where you can access all the JBM calculators yourself. They are free, and the JBM program is about the best around for accurately predicting trajectory.

JBM Ballistics Calculators

Mike

driftrider

Here's the chart I generated for your load:



To keep the chart a reasonable size I cut it off at 500 yards, but as you can see, mach 1.2 is reached between 375 and 400 yards, and the bullet drops subsonic just slightly past 500 (at 500 it's at mach 1.034). This chart corresponds closely to the one posted by semisane. I know the site he's using and it's pretty good, but the calculator doesn't have the functionality of the JBM calculator. Go to the link in my post above and click on calculators to see what I mean.

Mike

BIG.PAUL

Wow where did you find those programs at guys? I'm not sure it will ever do me any good....but it is fun stuff to know.

Wouldn't ti be nice to calc it out, then go out and shoot just like the chart says?