Long Bullets and Calipers

[Rick Teal]

The other day I was doing some experimentation with my Series II equipment.  I was wondering if it was possible to make one of my bullets longer than the 1.3" that Corbin says is the limit of this equipment.  

I took a 1.28" jacket, and made a 290 grain bullet with one of my tips that increased the length to 1.46".  Since the bullet seemed to come out OK, I decided to measure the diameter to make sure it formed properly in the die.  Instead of .358 the bullet measured at about .3572 (at least it was just over .357 according to my caliper).  I ran the caliper back down to zero, to make sure that it was still set properly, and it was.

Then I decided to check out some 220's that I made earlier in the day.  These measured the same as the 290's.  I was now really concerned.  Before calling up Dave Corbin, and bothering him with this, I decided to check out some of my store-bought .358 bullets.  To my relief, they also measured at .3572.  

So it seems my caliper lacks the accuracy I need.  I guess I'm going to have to invest in a better quality caliper - probably one of those digital jobs that measures to the 10,000ths that I seem to need.  But I've also learned that I can make heavier bullets with my equipment.

[talon]

Rick, I think the limit to Mr Corbin's dies are "about" 1.3". This is because he recomends at least one caliber of punch being into the die before pressure is brought to bare. That means, of course, a .224 bullet can  be much longer than a .454.  Too, I think all his dies are at a standard length to save costs in production, and that's another reason for the " about" 1.3".  (I'm not sure if he could or would make longer die bodies). If you try to make a long bullet, and start swaging pressure before that punch is at least 1 caliber into the die, it may work...once,   twice, even 100 times. Then you bend a punch and perhaps scar the die's interior. We all know that means another trip to the bank.  On the subject of measuring tools: you get what you pay for: a set of calipers and dials for a precision machinist costs thousands of dollars (US or Canadan, this is big money) Then, you go to school for a month to learn how to use them. Then you OJT for 10 or so years to learn the art of measurment. Is this worth being accurate to .00001"?  In making bullets?  ((grins))  

[Rick Teal]

talon:

I had assumed that it was some type of approximation.  

If I were making round nosed bullets, they wouldn't go as far into my die as my bullets do, but I'd assume that the 1.3" rule would apply to these as well.  Also, I'd think that since there is little swaging pressure applied to the last .20 of my bullets because that much is hollow or a hollow metallic tip, I could exceed the 1.3 limit by about that much.  I'll check to see how much of my punch goes into my die tomorrow.

I made some 297 grain 1.31" bullets using these jackets but without my tips.  The tips on these looked somewhat like the mag tip.  I could probably get these up to 300 grains (or a little more) if I made them with a lead tip.  I think I'll do a little experimentation with these as well.

Rick