Can you Bump size with small base dies?

[InfoLoader]

Hi, I have some rcbs ar series small base dies and i have a mostly used it for standard ar15 with 16" barrels, But i have a one precision gun that i wanted to get a more precise shoulder bump on the cases. I was wondering if these smwll base dies can be used for just bumping the shoulder back for this particular precision guns loads.or do i actually need regular full length dies?
Thanks for any responses..

 

[Blue68f100]

Any FL sizing die can be used to push the shoulder back. The SB die only reduces the area above the base a few more thousandths. I have yet to find a gun chamber that can not be sized properly with a good set of Std sizing dies. Not all mfg make their dies the same size. Some have more tolerance than others.

 

[InfoLoader]

So are you saying that small base dies are full length dies that also size full length plus a little more. Or are they not full length dies.

 

[InfoLoader]

I still wasn't completely sure of your answer to if small base ar dies can bump or not?

 

[Slamfire]

Hi, I have some rcbs ar series small base dies and i have a mostly used it for standard ar15 with 16" barrels, But i have a one precision gun that i wanted to get a more precise shoulder bump on the cases. I was wondering if these smwll base dies can be used for just bumping the shoulder back for this particular precision guns loads.or do i actually need regular full length dies?
Thanks for any responses..

I am an advocate of full length resizing, and for sizing the case less than the chamber. This is particularly important for gas guns, or failures to eject or failures to feed will occur. Even with bolt rifles you will have failures to extract if you are trying to create a case that crush fits or is exactly the length of the chamber. The basic problem with exact length is that fired cases react a little differently.

However, I have no reason to assume that a small based die will not partial neck size, which is what you are looking for. Tell us if you ever have failures to extract ..

 

[243winxb]

small base dies are full length dies that also size full length plus a little more.

Yes, ok to use.

From RCBS

Q: I see a Small Base Die Set listed for my caliber. Do I need these or should I buy a Full Length Die Set or Neck Die Set? How does each set differ?
A: The Small Base Die set is intended for use for ammunition to be used in auto, semi-auto, and lever action rifles so that the loaded round chambers and extracts easily. The Small Base Sizer Die sizes the case from the shoulder to the head of the case a couple of thousandths smaller than a Full Length Sizer Die. In certain calibers it also sets the shoulder of the case back a thousandth or two more than the Full Length Sizer Die. The Full Length Die Set or Neck Die Set is not normally recommended for ammo to be used in auto, semi-auto, or lever action rifles. The Full Length Die set is recommended for ammunition used in bolt action rifles, particularly for ammunition to be used for hunting. The Neck Die Set can also be used to produce ammunition for use in bolt action rifles. The Neck Sizer Die sizes only the neck of the case so it will hold the bullet firmly. It does not size the body of the case nor does it set the shoulder back. Neck sized cases will usually chamber for three or more firings, depending on the powder charge and chamber dimensions. However, over a period of time, a slight drag will be noticed when the bolt is locked. At this point, cases will need to be full length sized and the shoulder set back so they will chamber and extract easily.

 

[Walkalong]

Small base dies are full length dies that are little tighter near the base, thus "small base" dies. They are used just like any other full length dies.

 

[Bart B.]

Partial full length sizing pushes shoulders forward. The neck is not sized all the way to the shoulder, just "part" of it. They're often hard to chamber. Use a case headspace gauge to see how much.