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Small base dies

muleman69

USMC -1st marine Div. RVN
Do small base dies set head space or just the FL small base dies? Need to size base on my .280 A.I. and can't find an SB die for it that won't set shoulder back
 
Couldn't you set the die a few thousandths above the shell holder (With the ram fully up) to reduce body diameters and keep the shoulders at their desired place?
 
look at the case family and see if there is a longer case in the family..buy a small base there..or cut the top off of yours.

think using a 308 win sb on a 6br.30 br/dasher.

Do small base dies set head space or just the FL small base dies? Need to size base on my .280 A.I. and can't find an SB die for it that won't set shoulder back
 
I'd send 3 fired cases to Whidden and have a custom FL die made for your chamber. And I would trash the brass that's causing problems.
 
Do small base dies set head space or just the FL small base dies? Need to size base on my .280 A.I. and can't find an SB die for it that won't set shoulder back

You have a problem that a die any die won't correct. Either the brass has been shot without FL sizing and has work hardened in an expanded state or your brass doesn't fit your chamber. That means your chamber is too tight or your brass is to large and there isn't enough clearance to allow expansion and contraction during firing.
Start over with new brass and FL size every time.
 
Couldn't you set the die a few thousandths above the shell holder (With the ram fully up) to reduce body diameters and keep the shoulders at their desired place?
I'm having to set die with quite a cam over to get them to chamber easy. This is working but I don't really want any excessive head space. I'm thinking chamber polished will do it.
 
You have a problem that a die any die won't correct. Either the brass has been shot without FL sizing and has work hardened in an expanded state or your brass doesn't fit your chamber. That means your chamber is too tight or your brass is to large and there isn't enough clearance to allow expansion and contraction during firing.
Start over with new brass and FL size every time.
Brass is only once fired and we have been FL sizing. Thinking chamber polished will do it
 
look at the case family and see if there is a longer case in the family..buy a small base there..or cut the top off of yours.

think using a 308 win sb on a 6br.30 br/dasher.
I have never cut a top off, were do you make the cut? Just below the shoulder bump area?
 
Do small base dies set head space or just the FL small base dies? Need to size base on my .280 A.I. and can't find an SB die for it that won't set shoulder back

Muleman69, The case does not have head space. And then there is only one reloader that understand the other part of your question. Most reloaders believe the small base die sizes the base of the case, I find that impossible because of the deck height of my shell holders meaning nothing on the base of the case gets sized below .125" + the radius.

If I was concerned about shortening the case from the datum to the case head I would adjust the die off of the shell holder with a feeler gage. I have one (EK) chamber that is .016" longer than a minimum length/full length sized case from the datum to the case head, When sizing cases for that chamber I shim the die off the shell holder .014" for the magic .002" clearance and I use 280 Remington cases.

If you want to size the case near the web without changing the length of the case from the shoulder to the case head use a 30 Gibbs die or find a through the die sizer; meaning shove the case through a hole that is smaller in diameter than the case head diameter. And remember, the case head protrudes from the chamber and is not supported.

Or you can purchases a small base die and cut off the portion of the die you do not find necessary. It would make more sense if the reloader had someone make a die that only sized the case above the rim, that would stop the reloader from worrying about something the case does not have and that would be head space. And then it does not get simpler when the case comes with a belt.


F. Guffey
 
First let's try and identify your problem before removing metal. What does your brass measure .200" in front of the rim? Before and after firing? Tell us about the rifle, as in barrel and chamber, in detail.
factory Kimber MT. Accent ,Have to get back to you on measurements
 
I would still like to no how much of the base a SB die sizes ? I would guess the FL small base would size the base the same .Just like to now when asked .
 
If the brass is being fired in the same chamber I've never had any issue getting it sized back with ordinary FL or FL bushing dies. You can certainly get to much head space if you are not careful, and that will lead to case head separations in short order. (I've always set my dies up to be cammed over on my press)

The only time I've run into chambering issues is with brass that has been fired several times in a one chamber that is larger than another. That brass will never size down to reliably chamber in the smaller of the two. It may size so that some will chamber, but the rest will stick just forward of the web.

A full length SB die just has a slightly smaller dimension at the base. Any FL die can be set up to bump back the shoulder.
 
I would still like to no how much of the base a SB die sizes ?

The shell holder prevents the die from sizing the base of the case so it is the base of the die that is small. After that reloaders should determine the thickness of the case head from the top of the cup above the web top the case head, most would rather talk about it than to take their hands off of the key board. Most of my 30/06 cases have a thickness of .200" I have other cases that are .260" thick. It is not easy to size the base of the case and for the most part it is not necessary. I have suggested reloaders turn the case around and stick the case head into the die first; problem, I can not type slow enough for most reloaders to understand why.

I have dies that are 'really' small base dies. They keep ever case I shove into them and I do not have a case that has a small enough case head that will allow me to reverse a case and stick the case head into the die. I also have BAR dies, Bar dies are small base dies; when measuring I finds the BAR dies are good fitting full length sizing dies.

The sizing of the case head is limited by the shell holder. If the reloaders goes to grinding and decreasing the deck height all bets are off. For the few reloaders that measure case head diameter before and after firing .00025" is a good number for factory ammo.

F. Guffey
 

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