small base dies

[tc tom]

what is the difference between full length dies and small base dies and which is beter for loading for ARs thanks tom

[dahermit]

Some auto loading rifles will not function correctly with cartridges loaded with dies that do not remove the slight ridge (ring) found on fired casings. If there is such a problem with a rifle, the fix is to use small base dies (dies that will remove the expansion ring completely. However, removing that ring over works the brass inviting case-head separation after a few re-loadings.
My AR-15 does not have a problem functioning with just neck sizing. Therefore, I do not even full length size to get reliable functioning.
In short, if you do not need to use small base dies, do not use them. If you do not need to full length size, only neck size. Accuracy and case life will be better.

[steve4102]

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.


I load for several semi-auto rifles and have not yet found the need for a SB die. I do however always FL size by brass. Neck sizing for an auto-loader is just asking for trouble. Get a good set of FL dies for your AR and you will be fine.

Here are some good articles on the AR and other good stuff. You can also purchase his book on loading for the AR. He will tell you that never neck size for your auto-loader.

http://www.zediker.com/articles/articles.html



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[Alleykat]

Steve, I'm using the X die for f.l. sizing for my AR reloading. However, I'm considering using a Lee Collet Die with an undersized mandrel in station 2 of my 650, in order to increase neck tension. The decapping pin will be removed from the mandrel, of course.

[Sam06]

I think the SB die was made for the Remington 740 and 760 rifles. Some can be picky about what you put in them. I don't use a SB die set anymore now that I got rid of a 742 years ago.

I reload for several SA rifles: M1, M1A, Ar-15, Win 100 and have never need to use them either. I have a set in 308 and the only time I used it was when I had a Rem 742. It needed the SB resize to function 100%.

When reloading for a Autoloader you need to FL size the brass as stated above. You also need to watch length too. Trim often and keep the brass to Factory length. Most are picky about OAL of the cartridge too. Not just the OAL dictated by the magazine.

I would not go out and get a SB die set unless my rifle was not functioning with rounds I had FL sized. Even then I would look around for other problems before I went to the SB Die. Hope this helps.......Sam

[rn22723]

Here is some from the horses mouth so to speak info.

Direct from the RCBS Web Site
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.

[rn22723]

The use of SB die may be used for 308 LC brass that was fired in a sloppy MG chamber to ensure reliable chambering. Just one pass prior to the initial loading of the brass once acquired. Of course as listed in the post with the information from RCBS site there are guns that need SB as a matter of course.

But, from experience with auto loader to include the Mini 14, AR, M1 Garand, and M1A FL dies work just fine!


Using Neck Sized Brass is an invite to major malf. And, to advocate such is sort of a bad banana considering the # of new reloaders that are coming on board.

The best way to look at things when reloading for the AR or SA platforms is that you need need to have reliable chambering and extraction. If you are loading for on gun and it is not intended for self defense then messing with variables may well work for some. But, when loading for multiple guns and such that they may be employed for SD, the last darn thing I would want is to have a reload problem ie from neck sized pc of brass.

Now, with that said you can tune your brass to one chamber, and if you take the time and effort with the right tools to set up your FL die to only set back the shoulder enough to allow reliable chambering for one specific gun. This can be accomplished with a RCBS Precision Mic.

[F. Guffey]

Tc Tom, before you invest in small base dies try this, slide a shell into a shell holder, no press/die-nothing but a shell holder and case, and, a feeler gage, machinist type (those that use them know there is a difference between an automotive feeler gage and a machinist feeler gage, about $5.00 dollars and the machinist feeler gage blades start at .001), start placing the blades of the gage between the shell holder and head of the case to find the amount of clearance, RCBS is about .011 (30/06), Lee can go to .016, the amount the case can be raised with the feeler gage represents the amount the distance between the head of the case and shoulder can be reduced when sized in a good press.

The deck height of the shell holder is .125, to reduce the deck height some grind the shell holder, this is not necessary, a feeler gage placed between the shell holder and bottom of the case will raise the shell an amount equal to the thickness of the blade, with a good press, this will reduce the distance between the head of the case and shoulder when using this method, and everything being relative, reduce the dimensions of the body of the case, remember, the head of the case is in the shell holder and the first .125 is not sized, and the die has a radius resulting in .125 plus the radius, unless. someone has ground the bottom of the die, then we are back to "Before you invest in a small base die---", try this. Grinding a die and or shell holder or purchasing Redding shell holders at $11.00 each is not necessary, a $11.00 feeler gage is more than 'nice to have' and the gage can preserve the integrity of the equipment, it turns the press into a variable adjustable tool, in .000 thousands.

I have BAR sets, cases sized with these dies require tools that go beyond what most have available for measuring and comparing to detect a difference, the M1 Garand used the same ammo as the M1917 and 03 without small base dies because the M1 chamber was reamed with clearance at the mouth of the chamber, less than .0002 thousands.

You can use a feeler gage with a full length sizer die and reduce the distance between the head of the case and shoulder .011, that is .016 below a go-gage chamber or size cases that are as long as a field-gage length chamber with a feeler gage, or spend hundred, of dollars.

F. Guffey

[tc tom]

Thanks for the info I'm new to the AR game and didn't know if small base dies were needed

[C Bass]

Yeah - I wish I would have done a little more research before I bought my SB dies for my AR but I was just going off of the RCBS site.
Have people truly had issues with "overworked" brass with case/head separation and such from SB dies or is it mostly theory and myth?
I'm debating if I should replace my SB sizer with an standard or "X" die.

[amamnn]

You can find a nice quote on the Redding website that contradicts the RCBS sales pitch. It would be very unusual to NEED small base dies for any factory off the shelf gun.

[rn22723]

You can find a nice quote on the Redding website that contradicts the RCBS sales pitch. It would be very unusual to NEED small base dies for any factory off the shelf gun.

Well, try loading Magnum rounds for a Browning BAR without Small Base dies!

[steve4102]

Well, try loading Magnum rounds for a Browning BAR without Small Base dies!

OK, I will, I mean I do. I have a Browning BAR in 300WSM that cycles perfectly with Handloads. I size my brass with a Lee Collet Die followed by a Redding Body Die. I also load for a BAR in 30-06 with the same combination of sizing dies. cycles flawlessly.

[CrustyFN]

Thanks for the info I'm new to the AR game and didn't know if small base dies were needed

Not needed in my opinion. I have never needed a SB die for my AR. In fact everybody I know that loads for a AR hasn't needed one. I would go with a regular die set and see how that goes.
Rusty

[sig2009]

I have read countless articles about the RCBS X Dies and they are all favorable. I intend to get these for my AR.

[Tim R]

I shoot AR's for High Power competition and I shoot them a lot. I do not use a small base die for my "Wylde" chambers. What is important is to set your die up properly from the start.

[73-Captain]

Tim, glad you finally jumped in on this!!!

Hate all the BS that people claim about Small Base dies.

I've never used them. Figure if I need a Small Base die I'm doing something wrong. Instead of covering up the problem with Small Base dies and maybe making things worse, it is better to fix the real problem and use regular dies.

C.

[rn22723]

OK, I will, I mean I do. I have a Browning BAR in 300WSM that cycles perfectly with Handloads. I size my brass with a Lee Collet Die followed by a Redding Body Die. I also load for a BAR in 30-06 with the same combination of sizing dies. cycles flawlessly.

Well, geez in loading for a 300 Win Mag and 7mm Rem Mag they were needed, and regular dies did no allow for chambering. This could have been due to the belted nature of the cartridges versus the non belt nature of the WSM or 06...........

[wncchester]

"I'm considering using a Lee Collet Die with an undersized mandrel in station 2 of my 650, in order to increase neck tension..."

I love the Lee Collet dies but, for your desire, I'd try just polishing down the standard expander ball a thou or so.

That said, I wonder why you think you would benefit from a tighter neck.

[Tim R]

I use a Hornaday match bushing die for both 308 and 223. You measure your bullet and then go to .002 or .003 under the bullet size on the bushing. Has worked good for me.