Bullet Velocity

[Jeff Murray]

Somewhere over the past few weeks the subject of slippery lubes and dry lubes on bullet velocity was discussed.  There have also been many discussions about long barrels vs. short barrels and powder granulation.  I tried to find the specific posts but muscle memory was no help this time.  If you are interested in interior ballistics, there was a good discussion in the "Bevel Brothers" column in the November issue of Muzzle Blasts.  Friction, burn rate, time/pressure curves, gas/air volume effects - very interesting information.  Or you could just go shoot.  They also listed research done by Robert Miner at UNM Mechanical Engineering Department.  You can download the entire paper for free.  So if you like really strong coffee, get caught in a winter storm, or the temperature drops below 70 degrees for the warm weather boys, it might give you something to do - or help you sleep.  The site is: http//digitalrepository.unm.edu/me.etds/68.  It deals with modern rifles but the principles are the same.  Enjoy.

[Daryl]

Interesting, but I only got to the bottom of page 5. The math is a little more than I am comfortable with
as well.
Thanks - what I read was interesting but technical to the extreme.  My chronograph & the accuracy I
obtain, tells me all I need to know & more.
I will likely read more at a later date.

[D. Taylor Sapergia]

I just let Daryl digest the science, listen to what he says and try not to let my eyes glaze over.  Then I apply his wisdom and shoot for centre.

[WadePatton]

Thanks Jeff, but it took me too long to dismiss all the nitro-powders information in my head when I came to black.  They are similar but also quite different-and what I've learned is best for me is to leave those notions where they are and rely on the simplicity of the sphere and simple powders we use.

Daryl's observation that a slick lube takes more powder to achieve similar MV and accuracy is straightforward enough to grasp, just the same as clean barrel tends to produce a low shot-slightly out of any subsequent grouping with a dirty or warmed barrel. Less friction = less time in barrel.

One of the other things I had to throw away was the notion of any special caliber or loading that was equivalent to pet load or an "inherently accurate" cartridge form/caliber combo.  Such has long been well-known in pill guns, but as far as I've been able to surmise here (because I don't shoot bench competition, nor do I hang with the bench guys) there is no special caliber, but only a constant set of trade-offs between caliber and velocity, and bbl precision (in all parameters, especially ROT) and cost, plus the ball/patch components consistency that determines the accuracy of a rig.

Note: I don't mean this as a discussion of prohibited arms, but that to differentiate once again our internal ballistics from theirs. Should the moderators cut or edit the post I am not offended in the least. I tried to make it generic and referential without "dropping numbers" that sets everyone off into favorite old pill recitations.

Personally I don't even fool with the chronograph anymore.  What Daryl's observation shows is that guns work at a particular range of velocities better than another range of velocities, and that matching that speed is how to maintain consistency between loadings with different components. Seems to me to be a function of the bbl harmonics given the final shape of the bbl and how it's mounted. 

I like to shoot for group, adjust components for better groups, and shoot more for better shooting-bench test the loads, offhand test the shooter.

Thanks for the information all the same-I'm sure some might enjoy it. Bill Knight might have some information on how our powder behaves internal-ballistics-wise as it is somewhat different from the others. I do find it fascinating that we have been offered nitro-powder based subs in the past. Bill has already explained how one of those was constructed to produce appropriate performance in our guns. That particular powder wasn't produced long.

[Daryl]

I find it quite interesting that the calibre .69 is used in muzzleloading bench rest  competitions today.  Used, of course, with false muzzles (generally) and with extremely heavy
guns, in the 40 to 40 pound bracket, I was not at all surprised to see powder charges over 200gr. being listed.
In fact, some have stated they used charges to 180gr. in a .50 cal rifle.
I am not suggesting the guys here use these charges, just what seem to work under some circumstances at longer ranges of 100 to 200yards with round ball guns.

[Daryl]

Further point about bullets, vs. round balls. Within normal muzzleloading hunting ranges, no bullet from a muzzleloader will be seen to give as flat a trajectory
as a hunting round ball load.
This was as true back in the middle 1800's as it is true today.

[Mad Monk]

I find it quite interesting that the calibre .69 is used in muzzleloading bench rest  competitions today.  Used, of course, with false muzzles (generally) and with extremely heavy
guns, in the 40 to 40 pound bracket, I was not at all surprised to see powder charges over 200gr. being listed.
In fact, some have stated they used charges to 180gr. in a .50 cal rifle.
I am not suggesting the guys here use these charges, just what seem to work under some circumstances at longer ranges of 100 to 200yards with round ball guns.

Daryl,
Sometime look up Blue Mountain Muzzle Loading Rifle Association, Inc. on the internet.  That club is located near Shartlesville in Northern Berks County PA.  An old club that specialized in bench gun shooting.  About 30 years ago I was in touch with an elderly bench gun shooter who shot at Fiendship and Canal Fulton.  Once a year he came in here to this local club to shoot a big bench gun match.  There is a band of land across Northern Lebanon, Berks and Lehigh Counties that never really gave up black powder shooting.  They were still producing new percussion rifles in the 1920s up there. So when he came in to Blue Mountain I would go up to talk to him during the shoot.  He was one of those 200 grain charge shooters.  What surprised me was his main match rifle had a twist rate of 1 turn in 99 inches of barrel length.  He was pushing around 2,000 fps out of the muzzle of his favorite gun. 

[Daryl]

Daryl,
Sometime look up Blue Mountain Muzzle Loading Rifle Association, Inc. on the internet.  That club is located near Shartlesville in Northern Berks County PA.  An old club that specialized in bench gun shooting.  About 30 years ago I was in touch with an elderly bench gun shooter who shot at Friendship and Canal Fulton.  Once a year he came in here to this local club to shoot a big bench gun match.  There is a band of land across Northern Lebanon, Berks and Lehigh Counties that never really gave up black powder shooting.  They were still producing new percussion rifles in the 1920s up there. So when he came in to Blue Mountain I would go up to talk to him during the shoot.  He was one of those 200 grain charge shooters.  What surprised me was his main match rifle had a twist rate of 1 turn in 99 inches of barrel length.  He was pushing around 2,000 fps out of the muzzle of his favorite gun.

That's really interesting, Bill.  Also, using a slippery lube, I found in my .40 (48" twist) as well as the .45 (60" twist) than both of these guns needed just over 2,200fps to "show" their best accuracy at 50yards. That accuracy was on the order of 1/2" centre to centre for 5 shot groups. Ya know, I sold both of those rifles to guys who needed/wanted an accurate rifle & now I have to shoot against them. The only saving grace there, is they use their own idea of powder charges, patches and balls, not what those guns like.

[Mad Monk]

Daryl,
Sometime look up Blue Mountain Muzzle Loading Rifle Association, Inc. on the internet.  That club is located near Shartlesville in Northern Berks County PA.  An old club that specialized in bench gun shooting.  About 30 years ago I was in touch with an elderly bench gun shooter who shot at Friendship and Canal Fulton.  Once a year he came in here to this local club to shoot a big bench gun match.  There is a band of land across Northern Lebanon, Berks and Lehigh Counties that never really gave up black powder shooting.  They were still producing new percussion rifles in the 1920s up there. So when he came in to Blue Mountain I would go up to talk to him during the shoot.  He was one of those 200 grain charge shooters.  What surprised me was his main match rifle had a twist rate of 1 turn in 99 inches of barrel length.  He was pushing around 2,000 fps out of the muzzle of his favorite gun.

That's really interesting, Bill.  Also, using a slippery lube, I found in my .40 (48" twist) as well as the .45 (60" twist) than both of these guns needed just over 2,200fps to "show" their best accuracy at 50yards. That accuracy was on the order of 1/2" centre to centre for 5 shot groups. Ya know, I sold both of those rifles to guys who needed/wanted an accurate rifle & now I have to shoot against them. The only saving grace there, is they use their own idea of powder charges, patches and balls, not what those guns like.

Daryl,
When you mention getting just over 2200 fps out f the guns you touch on a point I would have liked to look deeper into when I was doing all of my chrono work.  There is a max velocity with black powder that is determined how fast the charge burns in the bore.  The old du Pont blasters' handbook had some comments in that got my interest.  They mentioned how slow black powder burns in the open as with trains of powder in dirt versus how fast it can burn in closed tubes.  They used to use lead tube burn rates in black powder QC testing.  Filling a lead tube with black powder.  Then flattening the tube a bit.  Then time how long it took for the powder to burn down through the tube.  Slow burning large grain powders took a longer time to burn down through the length of the powder column in the tube compared to fine grain powders.  This rate of flame spreading down through the tube is a major factor in what you will see as muzzle velocity.  The velocity limits with black powder was one of the driving forces behind the military switch to smokeless powders.  So there is a point where you simply cannot get higher velocities no matter what sort of charge you use and how long the barrel is.  In the old writings I saw hints at this but nothing definitive.

[Daryl]

Well, years ago, when Taylor first built me the .69, I was chronographing loads at the jail's gun range.
I got to 165gr., which had proved to give me excellent accuracy at 100yards and 1,550fps. I was interested
in seeing where the 'plateau' was with this 31" bl., so kept going. When I got to 200gr. 2F GOEX, I recorded
1,700fps.  When attempting to duplicate the 165gr. charges velocity, the person I was shooting with, asked me
a question, which interrupted my train of thought and I dumped in 2 of those 165gr. charges, then seated
the ball. It was obvious I had double charged the rifle as the ball was over an inch short of being seated.
I sat down and fired it anyway, over the chronograph screens. I was sitting in a 'chunk"- a 'round' of aspen
some 2' high, used as chairs on the range. At the shot, I was lifted to the standing position & the recording
on the chronograph was 1,770fps. Thus, for an extra 130gr. of powder over the 200gr. charge, I achieved a
mere 70fps increase in velocity.
The increase from 165gr. to 200gr., a 35gr. increase, increased the velocity 220fps, however a further increase
of 130gr. only increased the velocity an additional 70fps. Thus, there most definitely is a point of little or no return.
From this and my previous and post chronographing of muzzle loading rifles, it is obvious that in small bores,
much higher velocities are achievable than with large bores, however, if the ratio of the barrel length to bore size
was the same, it is quite likely that the higher velocities would also be achievable. Roughly speaking, a 42", .40 cal.
barrel is 105 calibres long and was capable of achieving over 2,200fps.  For the .69 to have an equivalent barrel
barrel length, it would have to be 72 1/2" long.
So, 2,200fps with a 482gr. ball - exciting.

[Jeff Murray]

I have a 32 caliber rifle with a 40 inch barrel, 1/66 twist.  With the slow twist it will shoot ball weight loads at 2000+ fps muzzle velocities with deadly accuracy.  i was surprised when testing the impact of the load on silhouettes that it would take down the ram at 100 yards.  The load also left a small crater where the 50 would leave a splatter on the metal.  I had to laugh when reading about being "stood up" by the double charge in a large caliber rifle.  Had a friend with a different sense of humor who loved to talk folks into trying his sharps.  He would shoot light loads and then slide in a full charge 50/140/710 for any  takers.  One kid had his glasses knocked off and nose cut by the tang sight and almost dropped the rifle.  The 32 is much easier on old bodies.

[Hungry Horse]

 My great grandfather lived to be a hundred and three years old. He was still living when I was born in 1949. He also served in South Carolina infantry at age fourteen during the Civil War. He told my Grandmother that nothing terrifying the Yankees they fought more than the young snipers in their outfit that shot their backwoods squirrel guns. He said a double charged squirrel gun was incredibly devastating because of the velocity. He said the little pea sized ball would deform on impact with the victims uniform leaving a ghastly wound for its small size. Those squirrel guns also cracked when double charged like a modern rifle, something most soldiers of the time were not used to. The little pea sized balls imparted a lot of fear in those facing them as they buzzed around them like mad bees.

  Hungry Horse

[Daryl]

Not hard to think of a visual with that descriptive, Hungry Horse.