What Dies for AR 15 5.56 Nato

Full length small base dies are recommended. There's no need to crimp.

Small base dies are generally not required unless you're trying to resize brass from something with excessive headspace, such as machine gun brass, or have a rifle with a very tight chamber.

I started with small base dies, but have since switched over to standard full length dies in an effort to help prolong brass life. I have no issues with them feeding in an autoloader, as they are still SAAMI spec.

A small base die simply sizes the base a little more and will help if your brass was fired in a fairly loose chamber and needs to fit into a tighter chamber. The disadvantage is you work your brass harder and may get a shorter life from it.

My first choice is the Dillon carbide set followed by the dillon steel die set both of which are small base 3 die sets with seperate crimping dies. If you choose to load mixed range brass that hasn't been trimmed to length I would get a Lee factory crimp die. OTOH if you are running a single stage press and all your brass is matching length you may prefer an RCBS die set which crimps as you seat and your round is done.

A case gauge is a must have item for properly adjusting your sizing die and checking for problems after sizing and crimping. There is no reason you should ever be at the range beating your buttstock on the bench trying to force the bolt open because of a bad reload.


PP

From Sierra.

Despite the oft-repeated advice that autoloaders, pumpguns and lever-actions require small base dies, the Service Rifles may be the exception that proves the rule. While it’s true that all of these action types lack the powerful camming forces of a bolt-action, the more generous chamber dimensions common to most Service Rifles are normally compatible with standard dies. Please understand that this is a general statement, and that there are exceptions to this. The point is, you don’t need to automatically go to a small base die set. Most of the standard reloading dies produced by reputable firms, such as RCBS, will resize fired brass properly to work in these rifles.

Link.

http://www.exteriorballistics.com/reloadbasics/gasgunreload.cfm

I load for a several semi-autos and I do not own a single SB die. Reg FL dies work perfect in my AR's, Rugers and Brownings.

+1 on what Steve said above. Run of the mill Lee, RCBS or Hornady dies will work just fine. I ended up with a set from Hornady which have been trouble-free. A previous set from RCBS kept bending the decapping stem due to failure to stay centered correctly, but that seemed to be specific to my particular set.

Learning the lube and correct application of lube which your die set needs seems to be the harder part of reloading for the 223.

The Dillon carbide set is totally unwarranted. Those seem to be needed only for professional, automated reloading.

If you do not have a set of 223 Remington dies and are reloading for an AR and plan to use cases from an unknown origin (aka not shot in your AR), I recommend getting a small base sizer die. With the variability of 223 Remington/5.56 NATO chambers the small base die won't hurt anything and will avoid some potential chambering problems.

If you already have a standard 223 Remington resizer die, there is no need to replace it until you absolutely know it is needed.

I use a small base sizing die for all my 223 Rem/5.56 NATO ARs so that I do not have to segregate brass between rifles. I do have a couple rifles with tight chambers that do not like cases fired in the other rifles unless the cases have been small base sized. It is an accumulation of tolerances thing.

I bought a small base sizer to use on brass that I've never used before but I doubt that it would be necessary since my reloads function well in about a dozen semi, pump and bolt rifles. I did have an AR that needed the chamber reamed but given the number of functioning guns I attributed the problem to a bad chamber rather than bad dies and sizing.
I don't think I'll use the small base beyond the first sizing of used range brass and will just stick with the Redding dies I have always used beyond that. I just use the small base die in a single stage FWIW.

The Dillon carbide set is totally unwarranted. Those seem to be needed only for professional, automated reloading.

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Dillon carbides last much longer than steel under normal (not perfect) conditions and create less friction sizing the base and expanding the neck while leaving a better finish behind.

Mind you at $153 a set they aren't for everyone but if you are a serious reloader and want the best .223 dies available they are the cat's pajamas.

I agree with you 100% on lubing, if you can't get your brass lubed properly you will never get consistent sizing results (headspace) or trim lengths if you are using a dillon trimmer. I use a lanolin oil and alcohol mixture sprayed on about 500 casings then I mix them by hand to get an even coat. It is very important that lubed brass be processed quickly or put in a sealed container where it won't collect grit.


PP

I've been using a standard Lee FL sizing die for years and never had a problem chambering a round.

The idea that small base dies shorten life has been around a long time and I believe the idea was created by people who did not set up their dies with cartridge headspace gages. If you push the shoulder back too far, which is possible with some small base dies, you will surely have case head separations.

Regardless of what die you use, get a case gage, I use these Wilson, and size the case to gage minimum, the lower step on the second picture.





For my gas guns I size everything with a small base die. I wish I could find small base dies for all calibers as it makes ammunition interchangeable across different rifles. You can get by with standard sizing dies, but be aware, your ammunition will be fatter than factory dimensions and occasionally your AR15 will jam. It takes almost no effort to find threads where the reloader used standard dies and his AR15 jammed.

Most of the bad sizing advice given on gas guns is offered by bolt gunners. As long as these guys can beat their bolt handle down by hand, and beat it open with a block of wood, they consider their ammunition good to go. They do things such as neck size, partial neck size, and many consider full length resizing something that someone else does. To function, semiautomatic mechanisms require much more attention to reloading details than bolt actions.

The small base die will only work your brass if the fired case came from a larger chamber. Most military brass should be re-sized with a small bass die. I have been using a small base die for 30 years and haven't had any issues. I also don't reload the brass past 6 reloads. If you are shooting from a tight chambered semi auto target rifle I would recommend a small base die. At least you are covering your bases that way.
The case lube you use is very important. Use a good lube and the small base die won't hurt anything.

I went with the RCBS small base X sizing die. I trim to 1.74 and with the mandrel on the RCBS small base X sizing die screwed down, it keeps the brass from growing. No more trimming!

I've been using a standard Lee FL sizing die for years and never had a problem chambering a round.

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I have the same experience and all of my brass is range brass that have been shot in many different guns unknown to me.

Small base dies are just another gimmick to sell to reloaders. Normal full length dies are made to size to SAAMI specs. Military chambers are usually reamed to the upper end of SAAMI specs so they will feed dirty nasty rounds. If anything a small base die might be beneficial to the guy that has a custom rifle that was built to minimum SAAMI specs and has a tight chamber. As for brass shot out of a machine gun or anything else its going to get sized to SAAMI specs in a full length die as well as a small base die. The brass might start out bigger due to the larger reamed out chamber of a machine gun but once its run through the full length die it will be SAAMI spec.

I would forgo the Wilson or similar case gauge and get the Hornady case gauge tool. All the Wilson tells you is the case will fit. With the Hornady you can measure how far the shoulder gets pushed out during firing and then measure how much the die is pushing it back during sizing and adjust your die to get the amount of shoulder resizing you want. I went through my 3 AR's and measured cases from each one after they had been fired. I then set the sizing die up to fit the tightest chamber and load all my 223 rounds to fit this one. All 3 rifles have sent a lot of rounds down range with no problems and my rounds feed it other AR's as well.

Plain RCBS FL two die set. No crimp. No problems. And I use One Shot spray lube.

Seems that only RCBS offers small base dies (to my knowledge). I wonder what dimensions all the other die manufacturers make their dies?

I only had one barrel that needed small base dies and that was a custom barrel for a .223 Contender. Factory ammo wouldn't even fit. I'm guessing the 'smith used a match chamber reamer by mistake. My 2 AR's and my T/C brand .223 barrel all use ammo sized with standard dies without any problems.

marchboom said:

Seems that only RCBS offers small base dies (to my knowledge). I wonder what dimensions all the other die manufacturers make their dies?

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RCBS sells a line of dies called "AR" dies, they come with a small base sizing die. RCBS also sells small base dies al-a-carte.

Redding makes small base dies.

Dillon dies are made "to minimum tolerances, sizing cases down to function in semi- and full-automatic firearms." (per Dillon's website).

I have seen comments that Dillon dies are small base.

I have a old set of Lee dies that I paid $5.00 for at the swap meet. I have made a few thousand rounds with them, not small base and they work just great.

"Seems that only RCBS offers small base dies (to my knowledge). I wonder what dimensions all the other die manufacturers make their dies? "

They all make their standard dies to standard SAAMI specs. There is no standard spec for small base dies. Most factory ammo is typically made a tad smaller than SAAMI minimums simply to insure it will chamber. Small base sizers are typically a couple thou smaller than SAAMI at the base, which makes the cases about like most facrory ammo.

The "conventional wisdom" of using SB sizers on factory autoloaders with standard chambers is "common BS". Size properly and keep your rifle clean, you should have no need for a SB sizer. Anyone thinking autos have little chambering power hasn't yet stuck his finger inside the ejection port when the bolt goes home.

Carbide sizers for bottle necked cartridges are horribly costly and have zero benefit for anyone but a commercial reloader who expects to run maybe 800,000 cases through his dies before replacement. Common steel dies are typically good for 'only' a tenth of that many.

plmitch said:

I have a old set of Lee dies that I paid $5.00 for at the swap meet. I have made a few thousand rounds with them, not small base and they work just great.

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I also just use LEE dies for 223 and/or 5.56. Have no idea if it is small, large or medium base, They all work, bolt or semi auto and fit in a Wilson case gauge.

I have a set of "normal" RCBS full length .223 dies and I have never needed anything else. If you buy quality dies and adjust them correctly you won't need gimmick, ummm, I mean small base dies. (IMO of course)

Dillon carbide! If you are going for match ammo, I would look at bushing dies.

"Dillon carbide! If you are going for match ammo, I would look at bushing dies. "

Why? I mean, what would they do that common dies can't do just as well? (For both statements.)