Heres the deal, there is nothing new under the sun. But I'd like to expand on several variants of the 40-82 cartridge, known as the 40-65 ron long, 40-65 long neck and the 40-82 crossno. All of these are 45-xxx parent brass necked to 40 cal to accept a .408 bullet and handle larger volumes of powder.
The idea is to make the 40 cal, with higher BC (above 400 gr) more competitive in long range.
Several folks have done their own deal with multiple dies, using a 40-65 die, running only part way down a 45-90 brass and making a pseudo two die system with a spacer at base to keep the case head fat like the parent brass.
I'd like to go a step further but I am treading in deep dookey potentially. Like a massive boom and the loss of my favorite body part, my head.
I'd like to take a 50-140 and neck all the way down to 40. Now this would be a neck, not a shoulder but the worry is, when the BP burns will the BP see a shoulder, a neck or a complete obstruction???
I have looked at an awful lot of BPCR rounds and NONE have that an extreme diameter change. I'd like to go fatter than the 45-70 case head, to some extent for efficiency (I am drawing a parallel to the 284 win, 308 win, etc where the powder column burn characteristic is “better” than say the 30-06. Same work performed in a shorter package, or very nearly). That and I can jam more BP in!
Secondly I'd like to have the ability to throat for 400+ gr bullets, not express stuff, and get the velocity upwards of 1500 where a 1-18 twist, or 1-16 twist will stabilize out to as close to 1k yards without worry of stripping rifling. Folks are saying that the 1-14.5 GM barrel will strip but it also is up to the 1000 yard task. An extra 100-150 fps is what I am trying to achieve. That and creating my own deal, for the sake of wasting money and doing it...... good or bad.
So the case head would be somewhere near 565 for about 1 inch, then reduce fairly quick to 505 (a shoulder similar to the 30-30 neck-body junction) The taper to the 40 cal neck would be following the 505 to 425 inch body of the 40-65 win.
So in other words, the case head is blown straight in fire form to the full diameter of 565, then taper as the natural 50-140. Then a 505 to 425 taper for an about 1.15, then a .75 or so neck.
The BP will only see the basic 50 cal base and a basic 40-65 cartridge, the neck wont exist as its essentially become part of the bore due to a deeply seated bullet. The neck woud be very long, as long as the 40-65 FL die allows me to press in, potentially 3/4 inch. I'd like to use the Snover bullet or longer as the basis and have all grease grooves in the neck and have the bullet ALL in the neck. This is an application specific cartridge!
Dies used to form would be 50-140 FL die mutilated to be used as a base sizer. The 40-65 die with a machined spacer would do the upper half, granted it can size and NOT crush the long neck. So far what I have read is it will go long with no issues.
Lastly I can use another carbide die, for multiple shots to just neck size. Like a pistol die.
The biq question, is there a limit to how much BP you can stack under a projectile with a severe overbore condition? and is the pressure going to peak so violently that it destroys my (Argentine) Rolling Block?
Anyway, any body????? Any thoughts (directed toward the project, not away from the project) would be appreciated.
Sharps built the 44-100 and it worked well. The 50-140 is just a fatter head version with a smaller mouth. I am nuts but not too nuts.
I think this can work, maybe kick like its been dropped form a 30 story building, not be accurate, etc..... but it will work.
Mike