Mile a minute ballistics

[Deleted member 46119]

Re: Mile a second ballistics

I'm sure it could be done.
Would need a turned monolithic bullet, front heavy enough that rifling would not be needed for stability(smooth bore). And friction reduced with tungsten disulphide.
Would need some of that magic surplus powder(extremely slow).
Would need to employ short/fat sharp shoulder angle case design to cause more powder burn -in the chamber, instead of adding to mass of the bullet.
Would need a 50cal diameter action to get enough barrel steel around the chamber.
Long barrel, like ~40".

Some of what you provide is very useful, some I don't understand.

• You are very right on rifling. Not really needed if the only goal is only to make the 5280fps.
• Mono-metal bullet. Yes, there will be an acceleration curve that will slump most projectiles. High lubricity brass vs copper or a copper alloy that is "stiffer".
• Additional lubricant such as WS2 or hBn.
• Short fat sharp angle case. Yeah, I get that.
• Long barrel. Longer is better until the point of friction heat or drag.

The ones I don't understand are slow powder and 50 cal action. I got really close in calculations with a .505 Gibbs (408 CheyTac) sized case. Powder is relative. We have so many available.

 

[Mikecr]

Surplus powders are difficult to get info on, but with research into huge overbore wildcats, you'll end up with enough info. Stuff like WC-860/WC-872.
They seem to produce chamber pressures common to matched reloading powders but burn more progressively, holding pressure longer. I've read they're very dirty, and less than consistent from batch to batch. But when reaching for incredible velocity numbers, you can't overlook them.

You need a larger tenon to get enough barrel steel around the chamber while using large diameter cases(short/fat). Otherwise this won't be viable as cases won't last long enough.