RCBS FL Dies

[450hunter]

Has anyone ever had a problem with RCBS FL Dies not resizing cases back to factory specs? I bought some once fired brass and down around/close to the base is about .002-.003 to big and will not chamber. I had a friend run the brass through his dies (also rcbs) and they resized and will chamber just fine. I was wondering if anyone else has had the same issue. Thanks

450

 

[bigedp51]

We live in a plus and minus manufacturing world and no two resizing dies and chambers will be the same. I have a Lee .223 full length die that sizes the cases smaller in diameter than my small base dies do.

Another problem with once fired brass fired in another chamber is brass spring back. For my AR15 rifles and once fired Lake City brass I use a RCBS small base die the first time the cases are sized. Thereafter I use a standard RCBS die on these Lake City cases.

NOTE, a small base die returns the case to SAAMI minimum dimensions, but my RCBS small base die only makes the case .0005 smaller in diameter than the standard RCBS die.

If you have once fired brass fired in a machine gun these chambers can be .004 larger in diameter. Meaning more effort when sizing the case and "MORE" brass spring back to its fired diameter after sizing. If you pause at the top of the ram stroke for a few seconds the brass will spring back much less.

Your die and your friends die shows you how dies can vary in size and it also shows you the problems you can run into using once fired brass.

Below some of my .223/5.56 dies and each one varies in how much it sizes the case.

 

[Gene]

NOTE, a small base die returns the case to SAAMI minimum dimensions, but my RCBS small base die only makes the case .0005 smaller in diameter than the standard RCBS die.

That is true. The Redding SB die works much better. I heard RCBS was coming out with a small base die that would completely squeeze the base.

 

[Laelkhunter]

What caliber? Is it a belted magnum?? If so, check out the collet dies by Larry WIllis. They solved my problem with the .340 Weatherby. If not a belted magnum, RCBS has a life-time warranty, and great customer service. Send the sizer die back to them with several brass that you are trying to resize. They will send you a new die.

 

[450hunter]

Laelkhunter,

It is 338 RUM brass. I will probably pick up another set of dies when one of the stores up here have some in stock (besides RCBS). Not many places here in Fairbanks deal with reloading supplies. Go figure...We are the Last Frontier and have the least amount of supplies. Also, I have used RCBS customer service before and they were great to deal with.

 

[Bart B]

Too Many Assumptions

Yes, it would help if we knew the cartridge involved.

What part of the resized case prevented it from being chambered?

Were there scratches on its pressure ring, the part of the case body about 1/10th inch in front of the extractor groove? If not, then the die was set too high in the press and didn't size the case enough to set the case shoulder back; instead the fired case shoulder was moved forward by the body being sized down.

I don't think any maker of standard full length sizing dies claims they size cases back to factory spec. Whose factory spec would they reference? They're all different. And they may or may not conform to SAAMI specs; it's voluntary for them to do so.

RCBS says their full length small base dies size cases below SAAMI specs. They also don't recommend such dies be used resizing cases for bolt action rifles. Over sizing cases is a sure and fast path to early case head separation by the work-hardening of the brass at its pressure ring.

 

[bigedp51]

Re: Too Many Assumptions

I don't think any maker of standard full length sizing dies claims they size cases back to factory spec. Whose factory spec would they reference? They're all different. And they may or may not conform to SAAMI specs; it's voluntary for them to do so.

RCBS says their full length small base dies size cases below SAAMI specs. They also don't recommend such dies be used resizing cases for bolt action rifles. Over sizing cases is a sure and fast path to early case head separation by the work-hardening of the brass at its pressure ring.

We live in a plus and minus manufacturing world and no two reloading dies and chambers are the same. And as I stated earlier I have a Lee standard .223 full length die that sizes the cases smaller than my RCBS small base die. And my .223 small base only makes the case .0005 smaller in diameter than my standard .223 RCBS die does.

The OP stated his die does not size his cases enough but his friends die does. Meaning we are right back to the plus and minus manufacturing world we live in and resizing dies "DO" vary in size.

A simple solution to this is to measure your fired case at several points along the body of the case. And then remeasure after full length sizing and "SEE" how much smaller the case is in diameter. In a semi-auto the case should be .003 to .005 smaller in diameter than its fired size for reliable extraction after sizing.

Intro to Full-Length Dies, Neck-Sizing Dies, and Small Base Dies
This article is part of Sinclair Int'l Step-By-Step Reloading Series. Most of the products mentioned in this article are sold through Sinclair's webstore.

Small Base Dies
A Small Base Die is just another type of full-length sizing die, but one that is typically used when reloading for semi-automatic rifles, like the AR-15, M14, or AR-style .308 rifles. (It may also work well for bolt guns that need extra sizing on the lower section of the case.) A small base die works exactly like a full-length sizing die, only it compresses the brass just a bit more, usually about .001″ more, and may even push the case shoulder back just a hair. Small base dies give that extra bit of compression to the brass to help make sure the case will properly extract from a semi-automatic firearm.

http://bulletin.accurateshooter.com...th-dies-neck-sizing-dies-and-small-base-dies/