Barrel length and velocity of patched balls

[hanshi]

While I can't give much ballistic info nor answer some of these questions posted I do have a bit of practical experience with rifles and chronographs. Consider for a moment that barrels are like teenagers and are just as different from one another as are the kids. They can be as recalcitrant, faithful, irritating, pleasing and rewarding as any teens can be.

In general the longer the barrel the higher the velocity in muzzleloaders, but only in general. Barrel condition, micro dimensional differences in bore size and consistency also have a lot to do with such comparisons. Consider this: (1.) A rifle I chronographed steadily gave speed increases of 40 + or - fps. Then at one point at 35 grains of 3F - adding 5 grains at a time - gave a velocity increase of well over 200 fps! It happened again at 55 grains although not nearly as dramatically.
(2.) Velocities can go up or down depending on patch thickness, lube and possibly your Zodiac sign. In one such session going from a .015" patch to a .018" patch bumped up speeds of 100 fps or so. And don't even get me started on weather conditions.
(3.) One last oddity. Another flint shooter that had the bench next to me on the club's firing line had a .40 rifle, just as I did, but his barrel was either 42' or 44" (forgot which) and my .40 had a 38" tube. We both fired over my chronograph comparing velocities and discussing results. His rifle was ahead of mine by a significant margin, but, that was before I switched patches and left his 42"/44" (?) in the dust.

I've always liked to work up a load, or two, that's the best I can come up with and then chronograph the results. I never use the chrono first. I'm with you all who say "find the most accurate load for your rifle". Only just make sure that load is powered to match your intended targets whether paper or animate.

 

[tenngun]

Well, I'm not so sure that is actually accurate information because when the powder (fuel) is burned up say in 28-30 inches , have a gas leak at the rear (flash hole) and still have 14 inches of barrel to traverse, what would make the ball go faster?

If a gun goes bank it means there is still an over pressure inside the barrel. A .50 say is still a mite less then .25 square inch. Air pressure is about fourteen pounds, or about three pounds in front of the ball. Even if internal pressure dropped to fifty pounds per square inch there is still a pressure differential that’s blowing that ball up the barrel. Even over compression of the air infront due to velocity
This is why a low pressure co2 discharges can blow a ball out

 

[longcruise]

I'm with you all who say "find the most accurate load for your rifle". Only just make sure that load is powered to match your intended targets whether paper or animate.

After having, over the years, shot many times over chronograph with many different rifles and load combinations I'm going to say that the above statement is the most realistic suggestion that can be made.

Not saying don't chronograph your guns. It's fun and educational but in the end what hanshi suggests will always serve well.

 

[Psycho Mike]

IF the only variables were muzzle length (or ignition system), then it would be likely that longer barrels would give higher speeds than shorter (or percussion would give slightly higher speed than flint)... BUT... the work that would go in to actually collecting the data to prove that would be substantial. At a fundamental base it breaks down to physics: In the former case, you continue to get propelling force acting upon the projectile for a (little) longer time, in the latter, you have less pressure loss (so slightly higher force) due to the nipple and cap vs. the open touch hole.

In terms actual, real-world measurements and results, there are simply too many variables and sources of variation to give anything approaching meaningful data: a couple grains of powder, a slightly off ball diameter or patch thickness, variations in lube, etc., etc., etc.... just too many factors to control to cut through the "noise" of the data without doing a significant number of shots (thousands, I would suspect).

It's nice to chrono to get an idea of how your particular firearm performs, but after that you're pretty much splitting hairs as a target or game animal have far more definite results with consistency and shot placement vs. being +/- a few fps here or there.

 

[westrayer]

The fly in the ointment is toting that long barrel gun around in the woods. However the long barrel does lend itself to easier off-hand shooting.

 

[Stevan]

Go to the doctor who tells you what you don't want to hear. So you go to another and another until you find one whom you like and believe. Listen to that one and take your chances. Muzzleloader Forum, same same. Now, did you find the info you like and believe? Cool! Let's go shoot !! Thanks, Steve

 

[Gordoncourtney]

IMO, for practical ML hunting distances it matters not on barrel length, as long as accuracy is there. One thing is most surely true. The maximum velocity should be where projectile leaves the barrel at the time the gasses are completely burned up. If the gasses are burned up only half way down the barrel, then from then on the projectile will be under more drag and reduce the velocity of the projectile due to that added drag.

Again, I do not think it will make much difference either way on game at normal ML hunting distances.

Not sure I totally agree with you. The ball is stationary in the breach. And the explosion excelerates it down the barrel, and it’s possible it will continue to excelerate for some more feet be it 5 or 20ft after it leaves a short barrel. But in a long barrel the bullet may start to slow due to friction before it’s only 3 ft up a 4 ft barrel , I am
Not trying to get into an arguments but thinking of applied maths from my college days 65 years ago. I’ll try to do some crono tests with my pcp air guns and write back. Mm yes an interesting subject on barrel length. I have a .45 old heavy barrel 24” long good bore but I ponder if it’s too short for BP and over 1600 ft / sec Recall BP has a max explosion of around 2100 ft sec I guess one could calculate the velocity at the breach explosion and velocity at end of barrel. But let’s face it it does not matter a hoot , barrel length is what suites you at the range of hunting.Mmmm for me never liked carbines , my latest ml
cape rifle has 32” barrels a big game ml 36”
Shortest 28” a Westley richards .5 double ml BP rifle but that would be for short range big game hunting

Just rambling along Nice to chat

Ps big game 577 rifle with 36” barrel





Nice to chat. N

 

[Eric Krewson]

I used to wonder how fast my selfbows shot, I thought they were lightning fast, every arrow that I shot through a chronograph was a disappointment, just middle of the road in performance, so I quit doing it.

I like the black powder velocity calculator above, fun to play with but alas, my .54 with a 38" barrel shooting a .530 ball pushed by 85 gr of 2F (a super accurate load) is very middle of the road in velocity (subtract 100fps for goex instead of swiss) and according to the calculator is only burning 98% of the powder.

Both my selfbows and my flintlocks have caused a bunch of deer to take a dirt nap in short order, that is my main focus.

I still think that calculator is pretty neat so I bookmarked it for future use.

 

[Gordoncourtney]

The most accurate muzzleloaders ever made had barrels under 30".

Think Gibbs of Bristol uk.

 

[longcruise]

and according to the calculator is only burning 98% of the powder.

That's one of the calculations that bother me. What were the parameters or data that were input into the model. Was it reams and reams of concrete data Or was it a collection of assumptions. If assumptions then the output simply confirms unconfirmed assumptions.

It's a very popular assumption that adding more powder simply results in more unburned powder being blown out the Muzzle. Offered as proof is the old shooting over snow test. And the photographic evidence of a huge bright flash of flames coming out the Muzzle. And maybe those are valid proofs. Personally, I think not but that's just my untested conclusion.

I'm in the near instantaneous complete ignition camp 🏕 Of course it may be a camp of one! I'm convinced, based on my own completely swagged assumptions, that all of the powder burns by the time the projectile has barely gotten started.

 

[Compressorguy]

Here is another link from the P-Max site that may give more insight regarding its intended purpose and the data it outputs. See their reference material below the simulator.

https://www.p-max.uk/black_powder.htm
I have no affiliation with the site, just something I found online and thought interesting, entertaining and informative.

 

[M. De Land]

That's one of the calculations that bother me. What were the parameters or data that were input into the model. Was it reams and reams of concrete data Or was it a collection of assumptions. If assumptions then the output simply confirms unconfirmed assumptions.

It's a very popular assumption that adding more powder simply results in more unburned powder being blown out the Muzzle. Offered as proof is the old shooting over snow test. And the photographic evidence of a huge bright flash of flames coming out the Muzzle. And maybe those are valid proofs. Personally, I think not but that's just my untested conclusion.

I'm in the near instantaneous complete ignition camp 🏕 Of course it may be a camp of one! I'm convinced, based on my own completely swagged assumptions, that all of the powder burns by the time the projectile has barely gotten started.

I believe it is Dr. Mann who did extensive testing of velocity and powder burn in various lengths of barrel would agree with you ! I think he was testing black powder and early smokeless duplex loading with both muzzle loaders and brass cased cartridges. I would need to consult his famous book (which I don't have a copy of) to verify this though.

 

[longcruise]

@M. De Land I haven't heard of his book. Maybe the library has it. Suppose I could check it out and get myself on some watch list.

 

[The Crisco Kid]

That looks like an English sporting rifle in the photos. It's a beauty. I like the style. A friend had one built in flintlock with a really nice piece of thin shell walnut.

 

[SDSmlf]

I believe it is Dr. Mann who did extensive testing of velocity and powder burn in various lengths of barrel would agree with you ! I think he was testing black powder and early smokeless duplex loading with both muzzle loaders and brass cased cartridges. I would need to consult his famous book (which I don't have a copy of) to verify this though.

You can get a ‘reprint’ of Mann’s book from a number of sources for about $35. Here is a link to a pdf of the book.
http://castpics.net/subsite2/ClassicWorks/The_bullet_s_flight_from_powder_to_targe.pdf

 

[Sparkitoff]

My .54 caliber flintlock had a 41" barrel. It was front heavy and hard to manage in a blind or walking in thick woods. I had it cut to 34". I used the same load as when it was 7" longer, and it was still accurate. Curious, I shot over the chronograph. I actually gained an average of 100 FPS velocity. I would have thought the opposite, but I am certain my before and after chronographing was accurate.

 

[tenngun]

That's one of the calculations that bother me. What were the parameters or data that were input into the model. Was it reams and reams of concrete data Or was it a collection of assumptions. If assumptions then the output simply confirms unconfirmed assumptions.

It's a very popular assumption that adding more powder simply results in more unburned powder being blown out the Muzzle. Offered as proof is the old shooting over snow test. And the photographic evidence of a huge bright flash of flames coming out the Muzzle. And maybe those are valid proofs. Personally, I think not but that's just my untested conclusion.

I'm in the near instantaneous complete ignition camp 🏕 Of course it may be a camp of one! I'm convinced, based on my own completely swagged assumptions, that all of the powder burns by the time the projectile has barely gotten started.

The powder seems to be all burned before the ball moves more then a few inches, but it’s still producing an over pressure. As long as pressure is greater on one side then the other there will be acceleration until a point is reached that friction with the barrel offsets the pressure to accelerate the projectile
A falling body can be used as an example. Gravity will add 32 fps to a falling body per second 32-64-96-….
But air resistance will slow that. A falcon can get up to about 300 mph, a human about 100. Gravities attraction is offset by air resistance
Dixie Gunworks got a .40 ball up to 2500 fps in a 42” barrel.

 

[longcruise]

@SDSmlf Thanks for the link. Downloaded all 416 Pages.

 

[longcruise]

The powder seems to be all burned before the ball moves more then a few inches, but it’s still producing an over pressure. As long as pressure is greater on one side then the other there will be acceleration until a point is reached that friction with the barrel offsets the pressure to accelerate the projectile
A falling body can be used as an example. Gravity will add 32 fps to a falling body per second 32-64-96-….
But air resistance will slow that. A falcon can get up to about 300 mph, a human about 100. Gravities attraction is offset by air resistance
Dixie Gunworks got a .40 ball up to 2500 fps in a 42” barrel.

Exactly how I think about it. The elusive factor is the friction or resistance and identifying all of the elements and then somehow quantifying them.

Maybe we need to get a 20 foot long barrel and and start shooting and cutting it down.

 

[tenngun]

Exactly how I think about it. The elusive factor is the friction or resistance and identifying all of the elements and then somehow quantifying them.

Maybe we need to get a 20 foot long barrel and and start shooting and cutting it down.

One thing I see in Lyman’s handbook is small vs big charges. In short barrels you get diminished returns from larger charges that continue to work well in longer barrels.
Conversely shooting moderate and small charges work better in shorter barrels.
I shoot a hunting charge at the range, but paper doesn’t need that. If your target is gongs or paper you can shoot cheaper with a low charge, and get all the fun you want.
A seventy grain charge is plenty for much eastren deer hunting. It might be a bit light for mule deer or elk.
A short barrel isn’t going to have much effect on most hunting and none on paper