Difficulty with Swaging Accurate .308 bullets

[jumper]

I am swaging .308 and .264 VLD bullets with rebated boattails.  30 caliber Sierra jackets reduced in diameter make beautifully accurate .264's.
Same jackets make lousy 155 gr. .308's though they look good in every way.
There is some indication that some boattails are shed from the .308's.
Suggestions appreciated.      
Jumper[/list]

[Donna]

Jumper-

The shedding of boattails could be caused by too much lubrication still left on the cores after washing and/or too much pressure. Make sure the lubrication is washed off completely and that just enough pressure is used to seat and form the rebated boattail and no more.

If too much pressure is used the lead cannot compress any more so the only avenue the lead has is to squeeze the jacket out of the die. The lead will make a ring, around the jacket, at the weakest point of ever thinning copper until the jacket cannot hold the pressure and at that point you will usually hear a pop as the jacket separates and the lead comes squirting out. When making a rebated boattail bullet the step of the jacket is the thinnest part and any residual lubrication left on the core will magnify this effect.

Donna :wink:

[talon]

Are the bullets shedding jackets or just the boattail portion? If so,what is the velocity of your VLDs? And, how long is the 155 grain bullets jacket, before the ogive its waged? What I'm thinking ( a lot of 'what-ifs' here) is that if there is an open or lead tip, with the lead 1/4" or so down into the jacket, and if the jacket wall is about .014" and if the velocity around 3100fps, the bullet may be exploding in flight from simple atmospheric resistance. Donna is much more knowledgeable in this area as it goes beyond stage 1  swaging.

[pjh421]

Very interesting comments.  I have had separations at the juncture of the shank and rebated boat tail too.  This happened while attempting to achieve a sharp, uniform edge around the circumference at the base of the shank.  I was also trying to get the jackets to “grow” the exact same amount by recompressing the core and jacket in the core seat die with the B2 punch.  It wasn’t worth the effort.  Donna is right.  A little jacket compression goes a long way.  So far I have only used J4 jackets so can’t comment on what others might be using.

Jumper, from reading your description, I don’t know for sure if you mean that your jackets are shredding in flight, as Talon guessed.  Anyway, you have to maintain a balance between tail, shank and ogive with regard to core weight.  If your bullet nose is too light, that is, the core is excessively short then the flight path will be erratic because the basic design of the bullet is unstable.

Try adding more core material or if you’d prefer, shortening the jackets slightly and see if things smooth out.  I would be interested to know if this fixes the problem.

Sincerely,

Paul