I picked up an entry level AR for myself for Christmas, and I'd like to add a set of .223 dies to my reloading equipment. Do you guys / gals find that small base dies are necessary for ARs? My guess is that I would be fine just full length sizing with the standard die set, but thought I would run this by a few people before I spend some cash. Thanks for your advise in advance.
Dies for AR (223)?
- Thread starter Scott_N
- Start date
The beauty about reloading is that there is no sure answers. 
It depends on your gun, more specifically your chamber.
Just from your post with no technical details, I would say you may be fine with regular fl as entry mil spec ar tends to have forgiving chamber. If your chamber is tight OR you pick up some range brass shot from out of spec chambers, regular fl die won't be able to resize it. That's when you need small base die.
It depends on your gun, more specifically your chamber.
Just from your post with no technical details, I would say you may be fine with regular fl as entry mil spec ar tends to have forgiving chamber. If your chamber is tight OR you pick up some range brass shot from out of spec chambers, regular fl die won't be able to resize it. That's when you need small base die.
I have a set of lee red box dies that worked fine for my run of the mill dpms ar-15 but I ran into some rounds that wouldn't chamber in my .223 wylde match barrel so I had to get a set of small base dies. If you haven't bought dies yet I would buy the small base set and then you know they will be reliable imho.
I buy once fired military Lake City brass and size it once with a small base die. Thereafter the cases are sized with a standard .223 die.
A 5.56 AR15 chamber is larger in diameter than a SAAMI .223 chamber, so technically a standard die will size the case more in diameter.
A cartridge fired in a semi-auto should be .003 to .005 smaller in diameter after sizing than its fired diameter.
A small base die will size further down the case at the bases. A small base die will make the case diameter .002 to .003 smaller than a standard die. And a small base die will push the case shoulder back .002 to .003 more than a standard die. The small base die will return the case to minimum SAAMI dimensions, and is harder on brass and can shorten case life.
Bottom line, chambers and dies vary in diameter and headspace length. I have a Lee full length .223 die that reduces the case diameter more and will push the shoulder back further than my RCBS small base die.
Buy a standard .223 die and if you plan to buy once fired or use range pickup brass then get a small base die.
I load for three AR15 rifles and a Savage .223 bolt action and have "several" dies. My favorite dies are Forster benchrest dies because the high mounted floating expander produces less runout than any other dies. And I have equipped all my older RCBS dies with the Forster expander and spindle assembly.
My RCBS .223/5.56 AR Series small base dies do not reduce the case diameter as much as my Redding body dies or my standard .223 Lee die. And only reduce the case diameter .001 more than my standard RCBS .223 die.
A 5.56 AR15 chamber is larger in diameter than a SAAMI .223 chamber, so technically a standard die will size the case more in diameter.
A cartridge fired in a semi-auto should be .003 to .005 smaller in diameter after sizing than its fired diameter.
A small base die will size further down the case at the bases. A small base die will make the case diameter .002 to .003 smaller than a standard die. And a small base die will push the case shoulder back .002 to .003 more than a standard die. The small base die will return the case to minimum SAAMI dimensions, and is harder on brass and can shorten case life.
Bottom line, chambers and dies vary in diameter and headspace length. I have a Lee full length .223 die that reduces the case diameter more and will push the shoulder back further than my RCBS small base die.
Buy a standard .223 die and if you plan to buy once fired or use range pickup brass then get a small base die.
I load for three AR15 rifles and a Savage .223 bolt action and have "several" dies. My favorite dies are Forster benchrest dies because the high mounted floating expander produces less runout than any other dies. And I have equipped all my older RCBS dies with the Forster expander and spindle assembly.
My RCBS .223/5.56 AR Series small base dies do not reduce the case diameter as much as my Redding body dies or my standard .223 Lee die. And only reduce the case diameter .001 more than my standard RCBS .223 die.
