sizing question

[Don Fischer]

I have always heard about using small base dies for auto loading, pump and lever rifles. Guess that the head can probably be sized down too? If that's it, wouldn't you think a small base die might tighten up a primer pocket on older case's? I've never use a small base die! But I have about 50 pices of 6.5x55 win case's that the pockets are getting loose in, just wondering if a small base die could tighten them up?

 

[F. Guffey]

If that's it, wouldn't you think a small base die might tighten up a primer pocket on older case's?

Not me; I am the one with shell holders that have a deck height of .125", meaning nothing on the case head gets sized below the .125" + the radius of the die opening. I have die boxes that go back to the 1960s, on the bottom of the box the instructions read: These dies are designed to be used with a shell holder with a height of .125". I added the 'word 'deck'.

F. Guffey

 

[F. Guffey]

But I have about 50 pices of 6.5x55 win case's that the pockets are getting loose in, just wondering if a small base die could tighten them up?

I could say it is more complicated than that but I won't.

In the beginning reloaders did not have the Internet, back then it was suggested the reloader measure before and again after. Back then reloaders did not want to exceede the maximum powder charge with powder and are a bullet that was too heavy. The area they were supposed to measure was the case head in front of the extractor groove and behind the case body. It was claimed the case head expansion for the case head was .00025". The reloader was supposed to use once fire/factory/over the counter cases.

And then came the Internet; it was about this time reloaders started making this stuff. I do not recommend reducing the primer pocket hole by swaging. If you insist on swaging the case head drill a hold in a plate to the diameter you desire, after drilling the hole force your cases through the hole to reduce the diameter of the primer pocket.

Back to "not that simple". When the case head is upset/expands the case head gets shorter from the cup above the web to the case head. And then at the same die the flash hole increases in diameter and the primer pocket hole also increases in diameter 'AND!' the case head increases in diameter. One more time; they say normal case head expansion over standard factory loads is .00025", there is a reloader that claims he has 45 firings on one case with no serious after effects, he could not tell me what the case weighed before he started and he did not measure the case head diameter before and again after all of those firings.

Working the case hardens the brass, I an not entertained by cases with worked hardened case heads, there is something about suddenly and without warning the case head failed, that would not be the same as case head separation.

F. Guffey

 

[hdwhit]

In general, the resizing die does not reach to or below the web of the case and so the primer pocket, which is at the center, bottom of the web would not be affected by either regular or small base dies.

 

[T. O'Heir]

"...a small base die could tighten them up..." Nope. Case heads are far too thick for that. The sizer die comes nowhere near the case head either.
An SB die only sizes the case body about 5 thou or so more than a regular FL die anyway. They're not necessary unless they are. As daft as that sounds. Usually only needed with some AR-15's too.

 

[F. Guffey]

An SB die only sizes the case body about 5 thou or so more than a regular FL die anyway.

I have small base dies, I have RCBS BAR dies, if the small base die reduces the diameter of the base of the case body .005" I want my money back. One more time, I have dies that are mistakes my mistake dies are .005" smaller in diameter than minimum length/full length sizing dies, the mistake dies keep every case I shove into them.

To decreases the small base sizing dies' ability to reduce the diameter of the case I shim the die off of the shell holder with a feeler gage. Again: There is something about the taper of a case the reloader does not understand. There is an advantage to owning mistake dies, to take advantage of the mistake the reloader must be able to determine the length of the chamber from the shoulder to the bolt face.

F. Guffey