Small base dies

A

ADIDAS69

New member
Has/does anyone use small base dies? Do/did you like them? Does/did it make a practical difference. RCBS specifically suggests not using them for bolt guns seems like an odd guideline.
 
SB dies aren't needed (as often) when loading for bolt action rifles as the chambering of a round is manual with the amount of force depending on the operator. SB dies are often needed when loading for semi-auto rifles as the chambering force is limited to what is delivered by the action spring.
Small base dies reduce cases a wee bit more than standard dies(possibly in several dimensions other than just the base) allowing easier chambering in tighter chambers.
We have 2 Savage bolt actions that require SB sizing for proper function and segregate cases for those specific rifles. Some of my AR platform rifles will handle most anything while others demand factory spec ammo. It is an individual rifle thing and less of a universal requirement.
 
Down through the years almost no one had heard of 'Small Base' dies until auto loaders became so popular, particularly the more accurate versions of the AR platform.

They REALLY took off when the ammo/brass shortage happened,
Mostly because people were using a lot more military brass, which is often fired through machine guns with excessively sloppy chambers.
(No, your civilian AR doesn't have a military chamber most times)

The advent of factory 'Varmint' rifles with tighter chambers also helped the 'Small Base' die sales.

What a 'Small Base' die does isn't much, some of the taper INSIDE of the die,
The taper that guides the brass into the body of the die,
Is reduced, so the die reaches down further on the case, most times just 0.002"-0.005"

Right above the extraction groove the case bloats or bulges,
The 'Small Base' dies simply push that bloat back in where it belongs just a tiny bit further down the case so it fits your chamber.

Now, the 'Correct' way to completely eliminate that bloat and get a flat case side again is a case roller (Case Pro 100 or comparable machine).
These are NOT cheap at about $1,000 each, but they will produce resized cases all the way to the bottom.

The 'Cheapest' way is 'Small Base' dies just bumping the bloat down the case a little farther...

You can lay a straight edge on the main body of a fired case and see the bloat pretty easily,
An accurate measuring tool and a SAAMI specification graphic will show up the bloat,
And you can measure length of a NEW case, fire that case, then measure it again, it will get shorter, indicating the case is swollen somewhere to prove this to yourself.

Most people won't have a tight enough chamber (WAY over SAAMI specification) to find this issue, other than some semi-auto shooters finding 'Mystery' rounds that won't chamber easily.

(The exception being Ruger 'American' bolt rifles having VERY tight chambers from the factory, the first American rifle I know of that doesn't need chamber work from the factory, but they are particular about case sizing)

Generally speaking, when using 'Once Fired' brass, you only have to knock the bloat back ONCE, since after being fired in YOUR chamber, the brass is 'Fire Formed' to your specific chamber.
Your chamber limits case expansion, so you don't have to go through it again.

Every round of Milbrass I condition gets run through a case roller since I have no idea what the end user is going to do with it,
Case Rolled, annealed, double sized & trimmed to length.
My customers get a CONSISTANT sized and annealed batch of brass, as close to SAAMI specification as I can make them in volume.
I don't have a clue if they are going to stuff that brass in a bench rifle, varmint rifle, AR or use it for cabinet door handles, so it's sized correctly & consistant when they get it.
Once fire formed to their particular chamber, they *Shouldn't* have any issues with it (I've not had any returned, and I have a 100% money back guarintee).

It's up to you, how much work & money do you want to invest?
 
Thanks guys for the info. What makes me wanna cry is that I assumed something called a Full Length Resizing Die apparently isn't. I just ordered up a Giroud annealer with the induction coil system so the case roller will have to wait a few months. I have the most problem with .308 Win so we'll start there.
 
I have a Remington 700 bdl in 3006 Where even new brass is tight in the chamber. It is the case body, checked with sharpie. Not so tight that I can't chamber a round but the bolt is harder to close and open on some brass. I just bought RCBS small base 3006 dies. I hope it helps my issues
 
Your chamber was probably cut with a reamer that was worn or had been improperly resharpened. If you know somebody with a sharp .30-06 reamer, you can take a T-handle and flood the reamer with cutting oil and gently turn it until it just moves fully to the neck.
 
I'm with Mobuck on this. My oldest son has a Browning A-bolt Medallion 7mm RM that does indeed require a SB die. RCBS, when I called, asked me to send them four spent cases from that rifle. Two weeks later, I get the cases back with a new SB sizer die. No charge! Loads like it should now. Some rifles are like that. Great CS from RCBS.
 
Down through the years almost no one had heard of 'Small Base' dies until auto loaders became so popular, particularly the more accurate versions of the AR platform.
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Not really; I have small base dies, I have small base dies that no one knew they were small base dies, I can turn my full length sizing dies into small base dies. And then there are glossary of terms; RCBS list small base dies as being a good fitting full length sizing dies. And then there are those; 'and then' moments. Just how small does the base of the die have to be to be called 'small base'? The M1 Garand uses the same ammo as the 03 Springfield and M1917:eek: no need to panic, the M1 Garand chamber did not require a case with a small base because the chamber in the M1 Garand had a large base; the diameter of the chamber in the M1 Garand was .00025" larger in diameter that the standard 30/06 chamber.

And then there was Browning and the automatic rifle; dies were made for the BAR.

F. Guffey
 
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The SBD's are most often needed for once-fired from someone else's gun. In that instance, if their gun let it enlarge a lot, after resizing in a standard die, the brass can spring back enough to fail to fit a tighter chamber. The small base die compensates for this by, essentially, over-resizing the case. This is why Dillon professional carbide dies for rifle are small. They figure the small commercial reloader is have to make brass from any gun fit any other gun, and know a standard dimension die cannot be counted on to do that in all instances. But once a cartridge has been fired in your gun, as long as the fired case doesn't slip too easily into a standard die, the standard die will make it smaller than it came out of the chamber. For a bolt gun, that should be all you need. Some self-loaders with tight match chambers can require making it a little smaller.

Occasionally, a worn chamber reamer will trip up the above by holding the shoulder back too far for a standard die to connect well enough in that area. I suspect that's what has happened when you get a gun that insists you use a small base die. On Savage rifles that seem to need a small base die, I would get a headspace gauge and and check that they weren't set it overly tight, and loosen the barrel nut and correct that if they did. Turning the barrel out a couple of thousandths may well take a gun that needs a small base die and turn it into one that does not.
 
I have a Remington 700 bdl in 3006 Where even new brass is tight in the chamber. It is the case body, checked with sharpie. Not so tight that I can't chamber a round but the bolt is harder to close and open on some brass. I just bought RCBS small base 3006 dies. I hope it helps my issues.
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Tight with new factory brass leads me to believe a SB die may not be a solution. You can take some base diameter measurements on tight brass and compare your numbers to SAAMI chamber numbers.

Also, along the lines of Uncle Nick's suggestion of reaming I would consider a pull through reamer, popular in 30-06 Springfield and 308 Winchester. They are easy to use, a headspace gauge is not required and they can be rented reasonably. All said and done you should have less than $60 invested and you will know you have a good chamber in specification.

Ron
 
"The M1 Garand uses the same ammo as the 03 Springfield and M1917 no need to panic, the M1 Garand chamber did not require a case with a small base because the chamber in the M1 Garand had a large base; the diameter of the chamber in the M1 Garand was .00025" larger in diameter that the standard 30/06 chamber. "

The Garand and most other military battle rifles are under no requirement to "meet commercial standards". Using any of those as a reference in a discussion of reloading is simply wasting space as the design and intended purpose had no relation to "reloaded ammo".
 
I first heard of small base dies in the early 70's. Everyone said you needed them for auto loader's and lever actions. Never felt the need for them It sounds like what is happening is the the die is actually re-sizing part of the head?
 
The Garand and most other military battle rifles are under no requirement to "meet commercial standards". Using any of those as a reference in a discussion of reloading is simply wasting space as the design and intended purpose had no relation to "reloaded ammo".
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"The M1 Garand uses the same ammo as the 03 Springfield and M1917 no need to panic, the M1 Garand chamber did not require a case with a small base because the chamber in the M1 Garand had a large base; the diameter of the chamber in the M1 Garand was .00025" larger in diameter that the standard 30/06 chamber. "
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One of the dumbest responses I have received when discussing the M1 Garand chamber was :"They could not hold tolerance's that close in the old days". And then I make a mistake when I assume; I assume most reloaders know there were at least three different 30/06 military chambers. And then there is that other thing; reminds me of the day the electricity went off in Boston. They gave up on fixing and decided to call one of the old retired electricians. He agreed to help but made it clear he would sent a bill. By that time the city was desperate.

It was not long before the electricity was back on but the city had a did not like the bill. The city complained, they claimed all he did was tap on a relay with a small hammer; they did not believe that small amount of effort was worth $10,000 dollars. He justified the bill by saying he charged them $100.00 for tapping and $9,900 for knowing where to tap.

F. Guffey
 
I've loaded for the M1, M1 Carbine, a cpl of AR's, and all of my auto loading pistols but have never needed small base dies of any sort. Too, I do not pick up range brass shot in a gun that I don't own. (Unknown handling to include hot loads, # of times reloaded etc.) That makes a difference, since the brass has formed to a limited number of chambers. I did load for 6 M1's at one point, and had no trouble with chambering problems. YMMV...Rod
 
Bought a sb rcbs die at the gun show for 12 $

The reason i bought it was because i load for 3 win mod 88's and one has a tighter chamber . Keeping brass seperated gun spacific is very problematic. So all brass get put through the sb die.

Works for me. No difference in accuracy. All shoot moa at 100yrds.

Seems to stretch the cases a bit more.
 
Seems to stretch the cases a bit more.
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Stretch cases? Reloaders measure before and then again after, after? That would be after the case is fired and that requires another 'before and again after' as in measuring before sizing and after sizing. If measuring before and again after was a habit reloaders would know/understand the effect the chamber has on a case when fired.

I can size a case with a common, ordinary everyday full length sizing die and get 25 different lengths when measured from the shoulder of the case to the case head. The 25 different case length would include cases for short chambers to cases for long chambers. Again, I have small base dies, I do not use them but I have them 'JIC', just in case.

Winchester and I had words, they built a rifle with the ugliest chamber I have ever seen. They said they were going to hone the chamber, or ream the chamber or they were going to polish the chamber and I asked: "How will that make the chamber smaller? Anyhow that had to be 17 years ago and I have not taken the rifle to the range. I did load 100 rounds for the rifle a year ago, the bolt would not close on any of them and I had a new box of Federal GMM 300 Win Mag, same thing' the bolt would not close. I ask Winchester for a rifle with a chamber that would match my dies or I wanted Winchester dies that would match their chamber.

F. Guffey
 
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