Small Based Dies

[PhillipM]

Genius! I never thought of that!

[Former Cav]

I have to use small base dies for my AR-15, it has a "match chamber / barrel".
For my M1A (.308 or 7.62 NATO more accurately) I just use full length dillon carbide dies.
I bought a Monadnodnock trimming tools years ago. I posted that info on this web site somewhere.
If you can't find it, email me on the private message with your email address (so no one else gets the address) and I'll send you JPGs and the info.
this tool cuts the overall length, chamfers the ID and OD at the same time. All you need is a bench size drill press or even a power drill and a vise to hold the power drill.
I got the info years ago from a champion (distinguished) NRA highpower shooter

[bigedp51]

The inside of the small base die is smaller in diameter and designed to size further down the case. The small base die is designed to reduce the case to SAAMI minimum dimensions, meaning the die is cut differently than a standard die. Below are two small base dies, the RCBS AR series die and a Redding small base body die and "BOTH" of them size further down the case.




Below is the Redding competition shell holder I use to size my .223/5.56 cases for my AR15 rifles and .003 shoulder bump. As you can see it is a +.004 shell holder and pushes the case into the die .004 "LESS" than the standard shell holder on the right. (.125 vs .129 deck height)



The AR Series RCBS dies or any small base die are not shorter or have the base of the die ground down. If the base was ground down you would be pushing the shoulder of the case back too far. I use the same +.004 competition shell holder with both the RCBS small base die and the standard RCBS full length die pictured above. Meaning you do not know what you are talking about fguffey or have even measured the dies you are claiming to be a expert on.

I have a standard Lee .223 full length die and it sizes the base of the case a smaller diameter than my RCBS small base die. And it will push the shoulder back .009 shorter than my GO gauge so we do live in a plus and minus manufacturing world.

Below are the chamber dimensions for .223/5.56 and .308/7.62 chambers, and a look at line "C" at the top of the list will show you the base diameter of the chamber reamers.
So we also live in chamber plus and minus world and dies also vary in size.

[fguffey]

I have a standard Lee .223 full length die and it sizes the base of the case a smaller diameter than my RCBS small base die. And it will push the shoulder back .009 shorter than my GO gauge so we do live in a plus and minus manufacturing world.
]

If any of that is true you have a die that is designed to size a case for a short chamber. Again; I turn my dies into dies that form/size cases for short chambers. No one ever ask ‘WHY?’ and worst they do not understand how. I cut chambers, before I start I want to know the length of the chamber from the shoulder to the bolt face. For me that has always been easy, I have three different ways of measuring the length of the chamber from the shoulder to the bolt face. I have started on barrels that were advertised as ‘short chambers’’ how short? When I found the chamber on one barrel was .225” shorter than a minimum length chamber I wanted my money back.

F. Guffey

[bigedp51]

F. Guffey

What wasn't true was what you said about the "RCBS dies in the black box are the equivalent of dies that have had the base ground off". What is true is that small base dies are the same length as a standard die and are cut smaller in inside diameter.

What is even more true is that dies do vary in size, meaning distance to the shoulder and in diameter. What is true is I have seven different type and brand .223 dies and they all vary in size.

Below a Colt 5.56 Field gauge at 1.4736



Below my adjusted Hornady cartridge case headspace gauge reading the Colt Field gauge.



Below a Lake City 5.56 case fired in my AR15 carbine.



Below the same case after full length resizing and .003 shoulder bump using the +.004 competition shell holder. If I had used the standard RCBS shell holder the case would have been .007 shorter than the chamber.



Below is a new unfired Federal 5.56 M193 cartridge in my gauge and if the standard RCBS shell holder had been used the resized case would have been .002 shorter than a factory loaded round. The cartridge below is .002 shorter than the GO gauge and if I use the Lee die making hard contact with the shell holder the resized case would be .007 shorter than the factory cartridge below.




There is a reason why I bought the Redding Competition Shell Holders and a reason why Redding made the biggest shell holder a +.010, meaning a deck height of .135

[fguffey]

F. Guffey

There is a reason why I bought the Redding Competition Shell Holders and a reason why Redding made the biggest shell holder a +.010, meaning a deck height of .135

I have the #6 Redding Competition shell holder set. i purchased it because the dealer had a price tag of $5.00 on it. That was 5 shell holders for $1.00 each. Not a problem but three of the shell holders were off by .001" each. I have never used them but I have them just in case. Then there was that part of reloading you missed; that was the time before skip's shims and Redding competition shell holders. I have an Eddystone M1917 with a long chamber. The chamber is .016" longer than a minimum length/full length sized over the counter new ammo. I know, most can not keep up with that but what it means the chamber is .002" longer than a field reject length gage; or .011" longer than a go-gage length chamber. For most that would be a problem but for me it is a matter for sizing cases that are the length of a field reject length gage. Again, for most that is a problem but for me it is a matter of finding a case that is long from the shoulder to the case head.

I use 280 Remington cases when forming cases for the long chamber. The 280 Remington chamber is longer than the 30/06 chamber from the shoulder of the chamber to the bolt face by .051". I would say "How can a reloader miss? When sizing cases for the long chamber I adjust the die off the shell holder .014" with the companion tool the feeler gage. After sizing the case I have .002" clearance. I could say "the magic .002" but reloaders believe the case has head space and no clue about the difference between head space and clearance.

Back to the .010" and the Redding competition shell holder, my Eddystone has an additional .006", even if I used the Competition shell holder I would have to adjust the die an additional .004" off the shell holder. I use the length of the case from the shoulder to the case head to off set the length of the chamber.

I suggest you get your money back on the Lee die, again, if it exist. I have dies that were made with mistakes. Your claim of the wonders of the small base die, I have small base dies that will keep every case pushed into them. Being one of the few that can measure a die for length and diameter I have had reloaders send me dies with a case stuck in them. I have suggested reloaders learn to measure the inside diameter of the die, so far all I have had are failures because no one has ever found a die that with a reduce diameter.

F. Guffey

[bigedp51]

Our plus and minus manufacturing world below showing resizing die differences.

Are Your Sizing Dies Overworking Your Rifle Brass?

http://www.massreloading.com/dies_overworking_brass.html

Table 2 - Inside Diameter Measurements for 5 different sizing dies