Can someone educate / explain "small base dies" to me?

[GONRA]

GONRA agrees wth Der Gebirgsjager's list of "small base die" calibers.
In my experiece: Add 5.7x28mm FN too.

Such RCBS resizing dies are valuable for producing "free chambering reloads" for semiautos.
>>> VERY IMPORTANT to avoid Slam Fires!!!!! <<<

None of that "neck sizing stuff" for Semiautos.....
Free Chambering and CCI Military Primers are the way to go!

[toallmy]

I use a small base sizing die on range brass the first time I size it for 308 and 223 brass just to avoid a swollen round not chambering .

[lightman]

I had the same problem with a Mark X Interarms, mine was in 7 mm Rem Mag. Robert

I also had chambering problems with this caliber in a Mark X Interterms rifle. I shaved a few thousands off of the shell holder and painted it to make it easy to keep it separated from my other shell holders.

[bruce drake]

I'm dealing with this very issue with a new AR10 upper in 6.5 creedmoor. My other reloads for my Mauser 98 chambered in that same caliber has no problem loading the cartridges but the new rifle is a no-go with the older reloads while new cartridges cases and cases being fireformed from 22-250 cases are feeding and shooting perfectly fine. And the 6.5 Creedmoor's parent case is a 250 Savage necked up and blown out into an Ackley Improved case design so using 22-250 brass eliminates having to trim down 308 Win cases and the resulting neck trimming/doughnuts that the thicker brass causes.

I ordered a RCBS 6.5 Creedmoor SBD Sizing Die from Midway and it should be here by Saturday for me to reform the older cases to the new rifle's chamber (I've already rebarreled the 6.5Creed 98 Mauser to a wildcat 22-6mm rem (5.56x57mm) for another winter project I have going on.) and then allow me to have dedicated brass for this rifle again.