Pressing milled BP into a necked case?

[Desertbuck]

My goal is to make a compressed BP puck INSIDE the case like the early British 303 only with out having to form the neck around a finished puck.Do any of you think if you dampened your milled BP and pressed it onto say 30/06, 7.62X54, 7.92X57 up to the case neck and some how had a small nail running the length from the primer hole to the neck then place in a hot box to dry, after drying remove nail Prime, seat Boolit and go shoot.
Would that work? What do you guys think?

[John Boy]

why not just use powder straight from the can an compress it hard?

[Chicken Thief]

why not just use powder straight from the can an compress it hard?

Compressed to hard you will get what's called a cigarette burn in a straight walled case. Ie. it will compact to a "solid" and only burn from the back. In a bottleneck that is disaster in the making.
Given an ignition cannel the charge will stay in the case and burn from the center to the case wall.
Pic of the original 8x58RD BP load
http://i295.photobucket.com/albums/mm153/Chickenthief/Skydning/M789%20Rolling%20Block/R0011245_zpsc4e2321a.jpg

[John Boy]

Thanks Chicken - never knew of such. What I have read - wet dry powder and then let it dry, the velocity will increase ~ 4 percent. Was in an 1800's book

[Chicken Thief]

The Danes prepressed the pill, incerted it into the case and then sized the neck on.

Oh and they got pressures that peaked at @ 2600bar~37700psi with a 215gr jacketed bullet.

[cal50]

What you have is construction similar to a core burning rocket motor if you are trying to expose a central core for ignition for more surface area / faster burn. For rocket motors this give a higher thrust impulse and faster peak thrust curve Vs and end burning motor. It works good for slower burning propellant to get performance similar to faster end burning charges. Shaped cores are more fragile and need to be handled more carefully.

Now you need a convergent and divergent angles added to your case......

[Seth Hawkins]

Compressed to hard you will get what's called a cigarette burn in a straight walled case. Ie. it will compact to a "solid" and only burn from the back. In a bottleneck that is disaster in the making.

Why is this a "disaster in the making" for a bottleneck cartridge? And just how hard is too hard when it comes to compressing the powder?

I've been compressing the powder in my .44-77 BN with the top of the powder a little further into the bottom of the neck than is shown in your pic and I haven't had any probs with how the powder burns. I'm fairly certain I'm compressing it enough that if it ain't becoming a solid it's pretty darned close.

Am I doing something wrong?

[Chicken Thief]

Why is this a "disaster in the making" for a bottleneck cartridge? And just how hard is too hard when it comes to compressing the powder?

I've been compressing the powder in my .44-77 BN with the top of the powder a little further into the bottom of the neck than is shown in your pic and I haven't had any probs with how the powder burns. I'm fairly certain I'm compressing it enough that if it ain't becoming a solid it's pretty darned close.

Am I doing something wrong?

Nah!
You would require a "svage" press to compact BP enough to get in trouble.
When you try to get 90grains+ into a 45-70 case and leave space for a boolit then trouble starts.
Imagine that you compress the BP in your bottleneck case so it in essense becomes a solid block of BP, then the primer will start the solid burning at the rear. The pressure will try to force the BP cake forwards but now needs to squeeze it down in diameter for the gasses to expand. That is trouble.
In a straight wall case pressure will just push the solid out the barrel and low velosity is the result.

Have you ever tried to dissassemble a compressed charge?
The top will be packed "solid, but downwards it rapidly will show that the kernals are just squeesed tighter together and readily falls out if poked with a little stick.
Compression is good because BP burns "slow" and the burn spreads quicker when the kernels are in contact.


Did this help?

[Chicken Thief]

Think of hard compressed BP as one way big kernel, that will burn from the outside.
A compressed load is permable to ignition/fire and will burn as a "sponge" from all directions.

[Seth Hawkins]

I understand now. There's compression. Then there's compression. You're correct about disassembling a charged case. As I got closer to the primer the powder was looser; it wasn't compressed the same from top to bottom. I also understand why it's dangerous in a bottlenecked case.

Thanks for the education.