Going Supersonic

[roundball]

It would make for nice conversation to actually chronograph a ball at the actual distance of say 50yds...in fact I think I'll run some tests like that after the first of the year when hunting seasons are over, just for the "gee whiz" value of it because that's the only value there would be for me.

Speaking only for myself, for this grand old form of shooting & hunting the bottom line really is what's happening at the target.
In my 42" x .54cal smoothbore, 90grns Goex 3F is the magic load for the tightest group at 50yds.
In my 38" x .62cal smoothbore, 110grns Goex 2F is the magic.

But regardless of what chronograph numbers might say at the muzzle or at 50yds, for my shooting as measured at the target, out of my Flintlocks, using my loading procedures, my components, even possible harmonics of those particular gns if such things actually occur in big heavy ML barrels...those loads in those guns are the best combination of velocity / power / trajectory / accuracy for my 100 yard hunting environment.

And that's the whole bottom line for me...don't care if a load falls into the sub-sonic, trans-sonic, super-sonic category as long as it eats out the bullseye at distance, and gets there quick with plenty of hunting power so the outcome is never in question.

Others mileage may vary of course...

 

[George]

And that's the whole bottom line for me...don't care if a load falls into the sub-sonic, trans-sonic, super-sonic category as long as it eats out the bullseye at distance, and gets there quick with plenty of hunting power so the outcome is never in question.

I agree, and that's the final test of any ballistics discussion, of course. Over the years, though, I've been endlessly entertained by considering both internal and external ballistics. On those days when I'm not shooting, for whatever reason, second best is to spend some time with the endlessly fascinating puzzles of what happens during the flight of the bullet. That's not required, it's not for everyone, and most don't have the inclination for it, but it as always been a great bonus, for me. Shooting wouldn't be the same without it.

Spence

 

[George]

Granted, this discussion centers on an elongated spinning projectile, but I would think the same issues of getting knocked off course would apply to a round ball without spin.

I don't think that's necessarily true. Precession or coning would have a different, probably much less, effect on a round ball because no matter how much it changes its orientation it still presents the same shape to the air. It's getting turned a bit sideways to the air that causes the problem with an elongated bullet during precession. Think of the difference in effect from tumbling with a long bullet and with a round ball.

Spence

 

[George]

So here's the question... how much powder is the minimum required to ensure that your .62 round ball starts off well above supersonic, and just as importantly, stays above supersonic as it passes the 50 yard mark?

I did chronograph loads from 70-110 gr. FFg in my 20 ga. smoothbore a long time ago, but can't seem to put my hand on the records. That was at the muzzle, not at 50 yards. I do recall that the highest velocity I recorded was 1600 fps. My regular load for that gun is 80 gr. Goex FFFg, and that gives me an average of 1475 fps. Running that velocity through my ballistics program shows that it passes back through 1100 fps at 45 yards.

It takes a lot of powder to accelerate a large round ball to a MV such that it will remain supersonic past 50 yards. Here are some results from my ballistics program, starting with a chonographed MV. In my old .55 cal. smooth rifle 100 gr. of FFg gave me 1538 fps, it would still be at 1195 at 50 yards. My .54 Hawken with 110 gr. FFFg gave me 1750 fps, dropped below 1100 at 80-85 yards. My .40 cal. shooting 65 gr. FFFg has MV of almost 2100 fps, drops to 1100 at near 90 yards. Same gun with 35 gr. FFFg gives me 1330 fps, drops to 1100 at less than 20 yards.

I don't believe passing through the speed of sound either going up or slowing down has any practical effect on my round ball guns as a hunter. For big game I always try for higher velocity, well above the speed of sound, because that lets me work with a flatter part of the trajectory, and that's a very good thing.

Spence

 

[tg]

"that's a very good thing."

Good point Bob I have opted for lighter loads and not taking shots over 50 yds i yse 80gr3f in my .58 fusil amd this has worked well but I am not comfortable with a 75 yd shot, more powder might change this...if I could see the Deer at that range :hmm: this is mainly why I closed up my range and got ride of the rifles plus I find the smoothbores more versitile and enjoyable to hunt/shoot.

 

[cgg]

Granted, this discussion centers on an elongated spinning projectile, but I would think the same issues of getting knocked off course would apply to a round ball without spin.

I don't think that's necessarily true. Precession or coning would have a different, probably much less, effect on a round ball because no matter how much it changes its orientation it still presents the same shape to the air. It's getting turned a bit sideways to the air that causes the problem with an elongated bullet during precession. Think of the difference in effect from tumbling with a long bullet and with a round ball.

Spence

I think you are on the right track Spence. I'm convinced that when I miss the target it must be because my roundball "keyholed." :rotf:

I enjoy contemplating ballistics and I always shoot my ML's over my chronograph sooner or later, just because I am curious. But it is accuracy, not velocity, that determines what load I hunt with. All of the .50 to .62 caliber rifles and smoothbores I have experience with have all shot well with loads somewhere between 70 and 90 grains of 3F and that provides plenty of power for the deer hunting I do. And the "sweet spot" always seems to be somewhere between 1200 and 1700 fps (and on the slow end of that in the smooth bore). JMO Have fun.

 

[11th corps]

You can buy a chronograph for less then $100. Its pretty interesting to see what your various loads are clocking. I have used mine on smokeless and my pre charged air gun too.

 

[Fred_Dwyer]

It basically says that the .8 to 1.2 mach velocity range is very unstable

That may be good in theory but there's too many good shooting rounds, (22 LR, + pistol rounds) that work in that velocity range to call that a rule.

 

[hunts4deer]

Roundball,

I often see your posting say that at a certain load your groups tightened up, but without specifics. I'm wondering how dramatic a difference you are seeing. Are you suddenly going from paper plate groups to 3 inch groups, or from 3 inch groups to cloverleafs, etc.? Please add a bit of detail so I can understand just how much difference you see when you hit the right load. Thanks in advance.

 

[roundball]

Are you suddenly going from paper plate groups to 3 inch groups

No, shots covering a paper plate at 50yds would be a 'pattern', not a group
:grin:
In the reference to load development for deer loads in my .62cal smoothbore Flintlock, my goal was to find a power load that kept all the shots on / in a 3" aim point sticker while shooting from a seated hunting position, no bench rest.
Around 90-100grns, the shots were hitting / touching the 3" sticker, then when I tried 110grns they closed up some...from about 3.25" to 2.50"...IMO a noticeable tightening considering a smoothbore and no solid rest.

The degree of difference is not so much the point as is the point that with PRB loads out of various .28ga and .20ga bores, the trend I've personally experienced in all of them is that the faster I push them the better the accuracy seems to...as if keeping them under a fuller head of steam for a longer duration to the target may minimize some possibe knuckle ball effect, but that's just speculation on my part.

The bottom line with muzzleloaders is that we..."you"...have to spend the range time to figure it out for your MLs, your equipment, your procedures, your skills, your weather, your eyesight, and the list goes on and on.
All you can do here at forums like these is look for trends, look for clues, ideas, etc...then plan several range trips and keep refining until you get it working the way that satisfies "you"

 

[KJGROHS]

Yea rightly spoken with sound wisdom A-Men to that .