Ok, it is me again.
That was a typo. My reloads are running .375 to .378" at the web. All were FL sized in a Lee carbide die, with a light lube of Lee lube. This die has sized about 200,000 rounds, so it may have worn a bit. I am borrowing a die from a friend and will see if it makes the cases any smaller.
The brass is all range pick up brass, so some will be more springy than others - resulting in variations in web diameter.
This range of cases diameters is still within spec and I would expect it to work well. In the past my ammo has chambered without incident in a SGW AR-15 and several different bolt guns. Bullets are 55 gr Lake City, seated deep enough to fit the mags.
I sprayed the DD chamber with brake cleaner and spun a chamber brush in it with an electric drill. It is CLEAN.
I have used a 223bolt rifle chambered with a JGS 223 Wylde reamer. It accept all the ammo, without a problem. I believe the Wylde chamber is based on a SAAMI minimum chamber.
The same ammo will not chamber all the way to the shoulder in the DD. None of it goes all the way, but most will chamber when the bolts hits the case. A few will not chamber at all.
A new IVI round will chamber in the DD without issue, but has very little wiggle. From all this I have concluded that the DD is tight. It will accept factory ammo, but not all reloads, because reloads are not sized back down to original cases sizes. The DD chamber is definitely tighter than my target rifle chamber and much tighter than the Norinco, which probably has some kind of generous NATO chamber.
The tight chamber might make the DD more accurate. I have not yet tested it that way. The owner's choice will be to use only factory ammo or to touch the chamber with a reamer. Or maybe we will discover another die does a better job of sizing the brass. I don't know if only 200,000 will wear out a carbide die.
I did not make the post to compare a Norinco to a DD. I was hoping others would respond by saying that yes, the DD has a tight chamber an needs small base dies or that theirs digests all manner of handloads just fine.
I will see if another sizing die has the same problem with the DD.
Anyone know if a Lee factory Crimp die would size an over-sized case, the way it does on a straight walled pistol case?