Anyone Swage 20 caliber bullets? Have a question.

[Sledge*]

I am getting ready to swage some 20 caliber bullets in my new dies from Corbin and want to make some 40 grain. I had been waiting for 3 months for J4 to make up their mind if they were going to sell 20 caliber jackets to the public but just got an email that they are not. I have a jacket reducing die to reduce 224 jackets to 204 and wanting to know if anybody can give me a correct answer on what length 224 jackets to order for 40 grain RBT open tip 20 caliber.  I'm thinking .640 but thought I'd see if anyone knows for sure.  I also have plenty of 224 jackets in .705 and .740 but I think these would be to long. I have a jacket trim die for my 22 jackets but they don't leave a good square edge when trimmed and I don't like the looks of the finished product.   Thanks in advance if anyone can help.

[talon]

Sledge*, the short answer is "no... sorry, I've never worked with .20 cal." I do know that one HAS TO work on the jacket length/core in a trial to develope that first prototype bullet you wanted to make. You can come close with just calculations, but a trial effort is required in the end. So much depends upon the ogive shape and the real (not nominal) jacket thickness in it's heal and walls. Too, what do you want as far as just how far down into the jacket you want your core to be in an open tip design? I am real lucky to have found an outfit that will give me jackets to the EXACT length I need, but for now that company only works with jackets above 32 cal. Below .32 I've always had to accept a jacket coming close to what I need and work around that restriction. Do you have a supplier that will cut jackets to specified length? I'd certainly like to know the address as I could use some help myself in the .257-30cal range. Otherwise, I've been thinking about and looking for a tool to cut off or grind down and then true up  jackets to a length I'm after. I do make tube jackets this way, but only for the larger cals and only when I absolutely have to. The folks on this board had a thread going about a year ago on this subject and you might want to review it. Finally, the Corbin jacket reducing/cutoff die set I use for 30 cal gives a nice sharp even edge and I've no problem with it, but I can see where a 20cal set would be a more delicate situation. A die maker I know said that making the cut off punches for his jacket making toolings was one of his most trying jobs: it's shape and OD had to be just right to give even a satisfactory product.  

[Rick Teal]

Like talon, I mainly develop my bullets through trial and error.

When I got my dies from Corbin, they sent me some sample bullets and components they made on mt equipment.  I measured everything, and made some to their specs.  I then cut these in half to see if they had come together the way I wanted.  I then made some adjustments to get the bullet I wanted.

Later, when I was trying another jacket, I would start with a core that sat the exact same distance below the lip of the jacket as my "ideal" earlier bullet.  This would allow me to save several steps in the development process.  

Whenever I make a new bullet weight, I save samples of jackets, cores, tips and partially manufactured jackets, cores and bullets for such comparison.

[Clint Starke]

Slege:

The only way to find out is to make reduce a few jackets, 50 or so, fill them full of enough lead to make a 40 grainer, and go shoot them.  The core should come past the datum line of the jacket into the point a little. Heck, you can make the lead come up to the point, they'll still shoot.

If the .705 jackets are to long, get some .600 and .640 J4's and try again. And don't worry to much if the jacket mouth isn't square. It doesn't mean anything. Contray to popular belief, the point of a bullet is far less important than the base, which must be square and true. An ugly pointed bullet will outshoot a bullet with a bad base everytime.

Remember, "Function before Form". The only looks that count are on the target. Some of the best bullets I ever made started out as mistakes. Like 78.8 gr. 6mm's on a .825" J4. I was told by some wannabe experts the heaviest bullet you could make on that jacket was a 68.  Those mistakes shoot 2/10" groups.

Have fun.

Clint Starke, retired bulletmaker.