Bullet design
- Thread starter Thamaz
- Start date
Help Support Muzzleloading Forum:
You will have a short bullet with a slow twist. I can give you the Lowe formula that I use for slug bullets. It is as follows: [(caliber x 3}squared] divided by twist x .07 = bullet length.
I can't get my computer to print it out the way I want it to. I hope that you understand what I am saying. You can use the Green Hill Formula but instead of using 150 as the constant use 130. :imo:
I can't get my computer to print it out the way I want it to. I hope that you understand what I am saying. You can use the Green Hill Formula but instead of using 150 as the constant use 130. :imo:
Let's see, .606 X 3 = 1.818
1.818 X 1.818 =3.3051
48 X .07 = 3.360
3.3051/3.360 = .984
That might be a maximum bullet length?
I know the longer the bullet is for a given caliber, the faster it has to spin to stabilize.
Of course, the velocity of the bullet has a lot to do with how long the bullet can be too but I assume the formula is set up for guns which shoot in the 900-1300 FPS range?
1.818 X 1.818 =3.3051
48 X .07 = 3.360
3.3051/3.360 = .984
That might be a maximum bullet length?
I know the longer the bullet is for a given caliber, the faster it has to spin to stabilize.
Of course, the velocity of the bullet has a lot to do with how long the bullet can be too but I assume the formula is set up for guns which shoot in the 900-1300 FPS range?
were they using the original molds for these minies they tryed? three things could be happening
1)Bullet not expanding to take rifling
2)Bullet striping the rifling from excessive vellocity
3)wrong weight bullet for amount of twist
I suggest a weak load and a minie with a thin skirt. Difficult mold to make, but maybe you can start with a commercial one and just increase the size?
Zonie; I get a little longer bullet than you did. The rifle twist was 47 and not 48. The length of the bullet I get is 1.005.
If you use the Green Hill formula, you will get a little longer bullet. The Green hill formula is: Bore X bore X 130 (constant not 150)divided by the twist = bullet length. .606 X .606= .367236 X 130 = 47.74068 divided by 47 = 1.0158 inches long.
Olie
If you use the Green Hill formula, you will get a little longer bullet. The Green hill formula is: Bore X bore X 130 (constant not 150)divided by the twist = bullet length. .606 X .606= .367236 X 130 = 47.74068 divided by 47 = 1.0158 inches long.
Olie
The length that I gave is the overall length. I am not sure just how to make the nose, if it should be round or come to some kind of a point. I also think that the nose should be short. You can draw it's shape out on a piece of paper to see what it will look like. Hope that this helps.
Olie
Olie
Cal.61: Are you using a cardboard wad between the powder and bullet. I use wads cut from cereal boxes. This may help. You can also use a paper patched bullet, Chase style (One wrap around the bullet).You need a wad over the powder for paper patched bullets. You need a good grade of paper. A lot of the slug gun shooters are using plastic coated freezer paper. I have some strong, .003 thick paper that I am trying.
Olie
Olie
cal.61: in some of the older guns, instead of using a bullet with grease grooves, they used a bullet that was solid. If you use a solid bullet in a barrel, with no protection you will lead the bore, so you put a paper patch around the bullet. Have you heard some thing this before?
Black powder and bullets work on up-set. When you set black powder off, the pressure goes up as high as it can hitting the back of the bullet like a sledge hammer, making the bullet fill the grooves. There is a split mila-second when the powder goes off before the bullet expands and some of the gasses go around the bullet. If you use a cardboard wad, this seals the barrel off.
I was on another muzzle loading hide and some people were taking high speed pictures at the muzzle of a smooth bore gun to see if the round ball spun (it didn't spin). Every time they shot the smooth bore gun they got a puff of smoke before the ball. They put a wad over the powder and it quit.
I have only give you part of the picture as I don't know how to exp;ain it any further. I hope this helps.
If you can get Ned Robert's book on Cap Lock Rifler as there is a lot of information in it.
Olie :m2c:
Black powder and bullets work on up-set. When you set black powder off, the pressure goes up as high as it can hitting the back of the bullet like a sledge hammer, making the bullet fill the grooves. There is a split mila-second when the powder goes off before the bullet expands and some of the gasses go around the bullet. If you use a cardboard wad, this seals the barrel off.
I was on another muzzle loading hide and some people were taking high speed pictures at the muzzle of a smooth bore gun to see if the round ball spun (it didn't spin). Every time they shot the smooth bore gun they got a puff of smoke before the ball. They put a wad over the powder and it quit.
I have only give you part of the picture as I don't know how to exp;ain it any further. I hope this helps.
If you can get Ned Robert's book on Cap Lock Rifler as there is a lot of information in it.
Olie :m2c:
Olie,
See if Igot You right, The "Wad" is a circular cardboard disc, with the same (or slightly bigger) diameter as the barrel- Right?
This Wad will act as a gasket between powder gases and the bullet, almost like a piston ring in an engine - Right?
If this is the case, we did somewhat like that with the revolvers. after pouring powder down the drum, we pressed a felt disc just big enough to demand force to be put in, then the bullet and finally the lube.
The paper wrapping is just for substitute of lube or protection of the rifling from beeing leaded. Well i sure see Your point! my dilemma is that i don
See if Igot You right, The "Wad" is a circular cardboard disc, with the same (or slightly bigger) diameter as the barrel- Right?
This Wad will act as a gasket between powder gases and the bullet, almost like a piston ring in an engine - Right?
If this is the case, we did somewhat like that with the revolvers. after pouring powder down the drum, we pressed a felt disc just big enough to demand force to be put in, then the bullet and finally the lube.
The paper wrapping is just for substitute of lube or protection of the rifling from beeing leaded. Well i sure see Your point! my dilemma is that i don
Cal.61: The wad is groove diameter plus a few thousands (.606 plus .004-.006 = .610-.612). Yes the wad will go into the base cavity, which is no good. This will hurt accuracy. What you need is a flat based bullet.
I don't know what machinery you have to do machining. I have a pretty good amount of machines. I make what are called half reamers, I take a piece of o-1 tool steel and turn it in a lathe to the bullet shape I want, then I harden it and grind half of it away plus maybe .002-.003. Then I hone the cutting edge a little. You have to drill a small hole in your work piece for the half reamer to follow. If you are making a mold, you don't drill the hole all the way through,just so deep. This will make a base pour bullet mold.
Olie :results:
I don't know what machinery you have to do machining. I have a pretty good amount of machines. I make what are called half reamers, I take a piece of o-1 tool steel and turn it in a lathe to the bullet shape I want, then I harden it and grind half of it away plus maybe .002-.003. Then I hone the cutting edge a little. You have to drill a small hole in your work piece for the half reamer to follow. If you are making a mold, you don't drill the hole all the way through,just so deep. This will make a base pour bullet mold.
Olie :results:
Cal.61
Glad to hear from you as you were gone for a few days.
First you get two blocks of metal the same size for the mold.You have to smooth the sides that go together and put alignment pins in the blocks,so the blocks will go together the same every time. With the two blocks put together, you put a center punch mark in the center of the seam of the two blocks. You now put the two blocks in the 4 jaw chuck and center the center punch mark with the center line of the lathe.
Now you take a small drill and drill a small hole (not to deep) in the mold blocks, then take your half reamer and make the cavity you want. you are working from the bullet base side of the mold. This will make a solid bullet for a paper patch.
For a bore size paper patched bullet I take the bore diameter minus one thickness of paper. this bullet can have a straight side. You can also make a tapered bullet which is groove diameter minus one or two thickness of paper at the base to bore diameter minus one or two thickness at the ogive (where the nose begins).
I wish that I could send pictures but I'm not that smart. I know just enough about computers to get into trouble. I wish that I had taken typing in High School but didn't, just hunt and peck.
I hope that you can understand what I am trying to tell you.
Good luck!
Olie :results:
Glad to hear from you as you were gone for a few days.
First you get two blocks of metal the same size for the mold.You have to smooth the sides that go together and put alignment pins in the blocks,so the blocks will go together the same every time. With the two blocks put together, you put a center punch mark in the center of the seam of the two blocks. You now put the two blocks in the 4 jaw chuck and center the center punch mark with the center line of the lathe.
Now you take a small drill and drill a small hole (not to deep) in the mold blocks, then take your half reamer and make the cavity you want. you are working from the bullet base side of the mold. This will make a solid bullet for a paper patch.
For a bore size paper patched bullet I take the bore diameter minus one thickness of paper. this bullet can have a straight side. You can also make a tapered bullet which is groove diameter minus one or two thickness of paper at the base to bore diameter minus one or two thickness at the ogive (where the nose begins).
I wish that I could send pictures but I'm not that smart. I know just enough about computers to get into trouble. I wish that I had taken typing in High School but didn't, just hunt and peck.
I hope that you can understand what I am trying to tell you.
Good luck!
Olie :results:
Olie,
Ohh. I'm here allright. I just had to survive the weekend.
Here in Sweden we have an old tradition having a Crayfish party at this time of the year. BBQ + a pile of crayfish some friends and the mandatory Swedish Vodka. Saturday was party and Sunday was recovering :redface:.
Your explanations is good indeed, my problem is the new questions popping up for every one answered ::
The tapered bullet design seemes interresting! But if You make solids, How do they expand to grip the rifles?
And the reamer, i guess You ram it in axially like a drill. But is it possible for You to move it radially to increase the diameter of the hole when in full depth? I mean if the reamer is shaped with lube grooves this has to be done, or the groves would not appear in the mold. I guess there will be servere squeeking and bad surface in the mold due to high cutting load of the reamers edge.
I guess You don't make lube grooves in this configuration.
:thanks:
C.U:
cal .61
Ohh. I'm here allright. I just had to survive the weekend.
Here in Sweden we have an old tradition having a Crayfish party at this time of the year. BBQ + a pile of crayfish some friends and the mandatory Swedish Vodka. Saturday was party and Sunday was recovering :redface:.
Your explanations is good indeed, my problem is the new questions popping up for every one answered ::
The tapered bullet design seemes interresting! But if You make solids, How do they expand to grip the rifles?
And the reamer, i guess You ram it in axially like a drill. But is it possible for You to move it radially to increase the diameter of the hole when in full depth? I mean if the reamer is shaped with lube grooves this has to be done, or the groves would not appear in the mold. I guess there will be servere squeeking and bad surface in the mold due to high cutting load of the reamers edge.
I guess You don't make lube grooves in this configuration.
:thanks:
C.U:
cal .61
Cal.61
I see where I said the wrong thing. I said to make your wads groove size and I said .606 (bore diameter).This is wrong as I don't know what the groove diameter is, you never told me.
I make my mold blocks halves just like Lyman molds, then I use lyman mold handles.
Olie
I see where I said the wrong thing. I said to make your wads groove size and I said .606 (bore diameter).This is wrong as I don't know what the groove diameter is, you never told me.
I make my mold blocks halves just like Lyman molds, then I use lyman mold handles.
Olie
Similar threads
