Velocity Estimation

[newton]

The talk on the REAL bullet velocity got me to thinking. Is there a way that we can estimate velocity of muzzle loading projectiles?

What I mean is that with a given powder, say Goex or Pyrodex RS, and a given projectile weight, can there be a pretty close approximation or grains to grains ratio?

I know that the bearing surface of the projectile can play a big part in it, but could an +- 500fps estimation be made?

Main reason I ask is because I am wanting to work up a load for the .45 ML I am getting and cannot find much information on it except for round balls. I am wanting to shoot the REAL's out of it and wanting to know the estimated velocity. I thought that if I took what a round ball velocity is then I can estimate a REAL velocity off that.

I know this is a far stretch here, but cant hurt to ask.

[Jim]

..... Is there a way that we can estimate velocity of muzzle loading projectiles? .....

The closest thing I can get to is Lymans "Blackpowder Handbook & Loading Manual". I don't know that you could find everything you want, but it seems there's a lot of data in the book, incuding expected velocities from various calibers, barrel lengths, powder choices, load values and projectiles.

[Nobade]

Quickload can do this quite well. List your parameters - bullet, powder, barrel length - and I can give you a decent guesstimate.

[newton]

Quickload can do this quite well. List your parameters - bullet, powder, barrel length - and I can give you a decent guesstimate.

Ok. Thanks. The gun has not arrived yet so I'll have to wait on length. But I will be using up the pound of Pyrodex RS I have and it will be a 192 grain boolit.

If I was guessing on the length it would be around 30"? But that is a big guess.

[newton]

The closest thing I can get to is Lymans "Blackpowder Handbook & Loading Manual". I don't know that you could find everything you want, but it seems there's a lot of data in the book, incuding expected velocities from various calibers, barrel lengths, powder choices, load values and projectiles.

Ok. That is probably the best thing to look up. I will break down and quit buying guns one day and buy a chronograph instead, but I just had to wonder if there is not a "estimation" formula out there for a given caliber.

But I guess there really is so much more too it, barrel length being a major consideration, that there really is not a very 'quick and easy' formula to it.

[newton]

One added reason I am thinking this is wondering just how slow I could shoot the REAL's. They have about 3/4 more mass to them versus a RB in a given caliber, so I would assume that you could push them a little slower but still retain the terminal ballistics of the RB.

That is not to say your going to keep anywhere near the same trajectory, but trajectory can be compensated for once known. But if a .45 cal RB is able to "effectively" take an animal at 75 yards with "X" amount of energy, then why couldn't a boolit do the same? But because the boolit has more mass to it, it could be driven slower.

The reason to all of this is the transition from sonic to subsonic of the boolit. I have to wonder if the 'design' of the REAL is one that this transition is very hard on. And may be why they can shoot so well at 50 yards, and horrible at 100. So the only way around this is to either keep them way above super sonic the whole way, or to start and keep them right around sub sonic.

So I want to try both ways. But if I do find that the low charge flies really well, I want some 'confidence' that terminally they will be comparable to a proven boolit. I know this can be somewhat determined by velocity and mass. I did get to thinking though, a 45 colt handgun only pokes most loads out at around 900 fps. And I know people hunt with them out to 50 yards or so. And I am guessing that in a rifle they run around 1200 fps. And that is plenty out at 100 yards.

I know that a lot has to do with shot placement and such. I am just trying to compare things in my head though. If that makes sense.

[KCSO]

Make a ballistic pendulum from scrap, that was my first chronograaph and it worked for years. I don't thinkk velocity was off by more than 10 fps as compared to my chrony.

[newton]

Make a ballistic pendulum from scrap, that was my first chronograaph and it worked for years. I don't thinkk velocity was off by more than 10 fps as compared to my chrony.

I'll have to look that up. Never hear of one.

[newton]

Well, I looked it up. I get the jist of it, and personally love physics. However, if I could just find something that would break it down into very simple terms that would be great. Like, h=height and m=mass and v=velocity.

But it seems like everything I find has to complicate it to the highest degree. But that would be a pretty neat experiment to do with the kids. I'll just have to study it some more. Thanks for the idea.

[colonelhogan44]

I had a thread on here a almost 2 years back where I built one and calculated bullet velocities for a senior engineering class. Click my username and find browse my old threads, and you should see it.

I think that one broke it down into simple(ish) terms.

[newton]

I had a thread on here a almost 2 years back where I built one and calculated bullet velocities for a senior engineering class. Click my username and find browse my old threads, and you should see it.

I think that one broke it down into simple(ish) terms.

Great. I did some more looking and I guess the thing that was hanging me up was "g" when multiplied by "h". I guess "g" is a standard of 10m/s(9.8 actual)? I understand its the gravitational velocity. I assume that it always stays the same. And then if thats the case, then you can convert it to f/s.

Ill look up your thread though. It helps to hear these things from someone who is describing it in a specific way.

[newton]

Found your thread. Nice!

Ok, so I did not choose my user name based upon 'intelligence'. I have the nickname of newt, but that was taken already. So in reality, I have the brain capacity of a newt, not Sir Isaac Newton.

So, in theory, is there a easy formula to plug in the mass of the pendulum and the height it swings? I'll look over it again and see if I am trying to make it more complicated than it is.

Thanks again, that would be a neat thing to set up and do with kids. I always loved hands on experiments.

[colonelhogan44]

Well, I dug through my old school documents, If you really want to do something with it, and don't want to wade through the math, I have a document that outlines the math and spreadsheet that calculates it all for you based on pendulum mass, arm length and horizontal travel when hit.

It's one of the products of my very expensive engineering degree.

PM me your email, and I'll send it to you for the low, low price of some pure lead ingots to feed my hawken :kidding:

It's cheaper than going to university!
:drinks:

[newton]

Well I suppose every action requires an equal and opposite reaction.

This is not where I thought this thread was going, but that is a good thing. I would most assuredly love to have the info. My kids will get a kick out of it, much less the idea of using the most advanced computer known to man(even though it will be receiving some help from a lesser computer) to figure the velocity of different guns I have.

[Boerrancher]

Well my methods are not very scientific, but I start light and load up until I hear the projectile crack as it is breaking the speed of sound, then I keep increasing the charge until the soot ring that forms in the barrel is gone, and I have my minimum and maximum load for the gun with that projectile. I know the weight of my powder charge and I know the velocity of the speed of sound, so I know for my minimum charge my velocity is around 1126 fps. Then from there with the increased powder charge I solve for x. Is it as accurate as a crono, or ballistics pendulum, no it isn't but it will at least give you a good guess.

Best wishes,

Joe

[nanuk]

remember, if you build a pendulum, the boolit has to stay inside it.

if it comes back at you, the reading will be far too high.


Boerrancher: what do you mean by the soot ring? I'm not familiar with that term.

[Boerrancher]

Boerrancher: what do you mean by the soot ring? I'm not familiar with that term.


If you shoot your ML a few times with a light load you start to notice a tight spot begin to develop in the bore as you are pushing the projectile down. This tight spot is a ring of soot or fouling. It is caused by incomplete combustion of the powder due to low pressure. As you increase your powder charge, you will notice that this tight spot will move further up the bore, because you are changing the pressure curve and interior ballistics. As you continue to increase the load you will continue to move this area of soot or fouling further up the bore. Once this spot has reached the end of the muzzle and can no longer be felt when loading you have reached your maximum powder charge for maximum efficiency. Any more powder and you are just creating a larger fire ball at the muzzle.

This method works for both smooth bores and rifles. In some of the older books on Muzzle loading, like the Lyman manual, it speaks of a "Hot Spot" moving up the barrel. and when the hot spot reaches the muzzle you have found your max powder charge. it is the same thing as the ring of soot or fouling. It is caused by incomplete, slow combustion. It takes more shots to find the max charge using the "hot spot" method, but if you insist on swabbing between shots then neither method will work to find your max powder charge. Also remember that if you change the projectile you will need to go through the process again because the weight of the projectile will have a drastic effect on the pressure and combustion of the powder. Also keep in mind that this max powder charge does not mean that it is the charge that will shoot the best, it is just the charge that will give you the most velocity and burn the most efficiency. Also it is to let you know that any more powder and you are wasting it.

Best wishes,

Joe

[nanuk]

Hey Joe

thanks for that info

I do swab... so never noticed, but I may just try without one day and see the effect.

great explaination.