RCBS dies..."small base" or regular ?


December 31, 2007, 05:49 PM
I need a set of dies for .30-06 Springfield so I can load for my M1 Garand. I was looking at the X-dies from RCBS. What is the difference between the "small base" and the other set?

I've reloaded for thirty years but I'll never claim to know all there is about it. Most of my loading has been pistol. I've only loaded rifle in .30-30. So I'm just not sure how this "small base" or "regular?" applies to me and loading for the M1.

Thanks for your help.


If you enjoyed reading about "RCBS dies..."small base" or regular ?" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!
December 31, 2007, 06:09 PM
According to this link (http://www.10ring.com/Categories/reloading/Other/RCBS_Dies.htm)

Small Base Sizer Dies are usually required for reloading ammunition to be used in automatic, semi-automatic, pump, slide and some lever-action rifles. These dies size the body of cases somewhat smaller in diameter and also set the shoulder back slightly more than a full length sizer die to ensure proper functioning in the actions of these rifles. Not recommended for ammunition used in bolt-action rifles.

December 31, 2007, 06:28 PM
You need to use small base dies if the cases have previously been fired in a machine gun. They have looser chambers, so you get more expansion of case. So if you buy military surplus cases, it is a good idea to use a small base die the first time you resize your brass.

After you resize once with a small base die, you can go back to using your regular sizing die on future reloadings. It doesn't matter if you are shooting out of a bolt action or semi auto. If you size with a small base die everytime, you work your brass to much and shorten life.

December 31, 2007, 10:15 PM
Thanks for the responses! This is a part of reloading I've never touched on. Even though I've had a .30 carbine for years, I've never reloaded for it. The .30-30 is a Win '94, all the other center fire rifles are mil-surp bolt guns. I'm glad I asked.

Thanks, again. Cool to be associated with knowledgeable folks.


December 31, 2007, 10:39 PM
In all likelihood, you don't need Small Base dies.

All they do is squeeze the case body smaller then regular dies, down to the part covered by the shell-holder.
Any die cannot re-size that part of the case anyway, no matter what you do.
That part is inside the shell-holder, and outside the chamber.

I have reloaded all manner of mil-spec brass out of Browning machineguns, M-60's, M-1's, M-14's, M-16's and everything else for going on 50 years.

I don't own a small-base die.
Nor have I ever found a need for one.

Properly adjusted, a regular sizing die will do the work necessary, 99.99% of the time.

IMO: All SB dies do is over-work your cases, and shorten the life of the brass, for no apparent good reason that I can find so far!


January 1, 2008, 01:23 AM

You came through for me again. I have only been reloading for 16 years learned from dad what a gift of knowledge to pass down. Well in all this time I have never used a small base die and for me I believe it is a marketing term. I will admit that I had just about given in because here lately hearing so much about them I started to believe maybe I do need them LOL :) But I have been reloading military brass (11years 4months Active Marine Corps) and have always just used the Full Length Hornady sizing die.

It is good to see someone else doing the same and giving me a sanity check to keep me grounded :)

January 1, 2008, 03:38 PM
I had a Ruger M77 in 30-06, shot it a lot, and used full-length resizing for all its reloading, everything worked well. I sold the Ruger and bought a Remington 7400, also in 30-06. Still had some left over reloads, they didn't work well in the 7400, several kinds of FTE, failure to chamber, etc. I attributed it to a new gun that needed to be broken in. Old reloads never did stop having problems, so I bought a SB sizer die. End of chamber and ejection problems. Shot some of the old reloads today, still having chambering problems. All brass has been trimmed to proper length so that is not a factor. I have maybe 1000 rounds of brass, all at least 30 years old, don't shoot that much, not worried about excessive use. I anneal after a few reloads, can't remember last split case. I still have both full-length and SB sizer dies, but it's the SB die for my 7400. Still looking for a good load for 150 gr Speer Grand Slams, have about 800 of them left. Can't find anything to beat 56.0 gr of H414, CCI 250 primers, and 165 gr spire points. This experience may or may not apply to M1s.
Darryl in AR

January 1, 2008, 03:57 PM
If by chance you do run into a tight chambered rifle like the Rem 7400 above, first try this.

Resize a case normally in a regular die.
Then smoke the case with a candle flame and carefull chamber it.

When it comes out, you can clearly see if you have case body interferance, which a small base die would address,
or shoulder interference, which adjusting the regular die correctly would address.

My shooting buddy of almost 50 years has an aversion to adjusting his sizing dies so he can feel a hard bump when the press linkage toggles over.
He has reloaded as long as I have, and still has problems with hard to chamber loads every time he gets a different caliber rifle.

So, he calls me up to see if I think he needs a small base die.
I tell him to screw the dang sizing die in another 1/4 - 1/2 turn so he can feel it bump over at full stroke.

That always cures his "perceved" small base die need!

And this has been going on for 40+ years now! :banghead:


January 1, 2008, 04:10 PM
That's funny!

For some reason it boggles peoples minds when you tell them that if they aren't caming their press over against the die they're not FL resizing.

When people have chambering issues they can be cured with rcmodels advice 9 times out of 10

January 1, 2008, 04:50 PM
Hornady and RCBS 30-06 full length dies (not small base) work just fine in 3 Garands, Rem 742 Woodmaster semi, and Rem 700 bolt action rifles. Don't have a need for small base dies with my rifles. I do recommend a case gage such as the RCBS Precision Mic to help adjust your dies for only pushing the shoulder back to certain dimensions. Make sure on your Garand that primers are seated below flush, and cases trimmed for o.a.l. You are aware that Garands need certain speed powder such as IMR 4895 or 4064 powder?

January 2, 2008, 08:58 AM
I use a sb die on my innitial resizing for my ar's. they have worked well for me. In my ar10, I did not do this for the first resizing and had plenty of problems for the first few rounds. when getting back to the bench, I used the sb dies for the next loading and the loads worked perfectly. I have been loading for at least 15yrs and this method has worked well for me. I do use alot of lc and other military cases. RG

January 2, 2008, 09:16 AM
I have been reloading .223 for my Mini-14 for years, and an AR for a while, and I only use a standard RCBS sizer. No problems. I have a new AR now and do not expect any problems there either.

Don't Tread On Me
March 4, 2008, 04:52 AM

I can't stand all this small-base or regular nonsense of RCBS.

Just use a Lee resizer. It automatically works perfect with autoloaders. No small base or regular base nonsense. One die. Simple. Works. Just as accurate.

I have never had a stuck case or a failure to chamber with a Lee sizer EVER. In my bolt actions, I've produced total tack driving accuracy with those same dies.

Any case I've sized with Lee has always dropped right into the chambers of my firearms and right into the case gauges I have. No issues.

I've heard of people with AR-15's "needing" small base RCBS to achieve reliability because nothing else would work. If that's the case, get rid of that lousy barrel because there's something wrong with the chamber. It's the gun, not the dies (assuming they aren't defective). My loads have no problems chambering and extracting from tight match grade chambers in AR-15s.

Get the Lee. Very simple. Extend the ram to the highest position. Screw in the die till it touches the shell holder. Drop the ram, add a 1/4 turn. Lock it down. Every case will now work in any non-defective firearm.

March 4, 2008, 11:20 AM
Well, there certainly seems to be a division of opinion here.

I'm in the same boat, of having to make a decision between the SB & reg full length sizer die. And of course it is a Garand.

I've been reloading for close to 45 years, and in that course of time litterly loaded hundreds of thousands of rounds, yet here I am, uncertain as to which die to buy!!

So, how many Garand owners do we have using SB dies, and how many are using the regular full length sizers.



March 4, 2008, 12:51 PM
I have yet to use a SB die on either my AR OR my Garand. My Garand eats my reloads like candy and begs for more. Same for my AR and those of a shooting buddy. I use standard FL Hornady new dimension dies for both.

March 4, 2008, 04:51 PM
Ref S.B. dies; "All they do is squeeze the case body smaller then regular dies, down to the part covered by the shell-holder."

Actually, all S.B. dies do is restore the body of a case to factory tolerance. "Normal" size dies allow a couple or three thousants of unsized brass to help compensate for sloppy factory chambers. It works too.

Many commercial lever/pump/autoloaders have little camming power so tight ammo can cause difficulty in chamering but even that's not really common. Dies for lever gun cartridges take that into consideration so they are usually made to S.B. type tolerances.

Garands seem to have plenty of cartridge insertion/camming power so it's rarely a problem!

March 4, 2008, 05:46 PM
Actually, all S.B. dies do is restore the body of a case to factory tolerance. "Normal" size dies allow a couple or three thousants of unsized brass to help compensate for sloppy factory chambers.

ranger335v has got it right. The part of the case that the SB restores to unfired factory specs is the web portion, which is slightly above the shellholder. This is normally only needed when you are dealing with machinegun fired brass, or brass from someone else's rifle that has a generous chamber. A SB die does not "set the shoulder back slightly more". The degree to which the shoulder is bumped back is purely a function of how far the sizing die is screwed into the press.


March 5, 2008, 02:42 AM
I use regular RCBS '06 dies in my '06 M-1's (I do have one in 308) and I use GI brass. Cases sized with the plain 'ole RCBS '06 dies has won me money and matches. Yeah I have to trim once in awhile but I can get about 10 reloads out of the brass before the rim from the extraction groove get too beat up.

March 6, 2008, 12:40 AM
I've had a bunch of M1's. I've never seen one with a USGI barrel that needed SB dies.

You'll have to scour the earth to find 30-06 that's been fired through an MG, so that's not going to be an issue like it is with surplus 308 brass.

If you enjoyed reading about "RCBS dies..."small base" or regular ?" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!