My first 223 Rem (actually 5.56 Nato) rifle is a Colt Match Target. I bought an RCBS standard die set for it and all was well with cases shot in my rifle.
At a Service Rifle Match, a fellow competitor was short of ammunition so I offered some. The fellow accepted and then his gun jammed, not chambering my ammunition.
We discussed a bit on match chambers and various rifles.
Shortly there after, I bought a CMP Compass Lake Match AR-15. Shooting reloads previously fired in the Colt would not chamber in the Compass Lake. Hmmmm.
Besides the RCBS sizer, I bought a Redding standard sizing die and the issues caused by the RCBS sizer went away.
After some investigation I found that lots of folks don’t have issues with chambering but have not experienced problems. But problems are there.
In my opinion, my problems with the RCBS sizer are due to tolerance error. The die is probably cut on the large size while the chambers are cut on the small size.
With measuring equipment I have (calipers and micrometers) I can’t see a measurable difference in cases that chamber and cases that do not.
With better measuring tools, the difference may be noticeable but the cost of the measuring equipment may be more than an average reloader is willing to spend.
In my opinion, particularly with 223 Rem/5.56 Nato rifles, the tolerance allowance is more variable between chambers, ammunition and sizing dies. This along with the large number of rifles chambered in the cartridge can lead to insufficient sizing and the associated chambering problems.
What one does with the knowledge and knows what to do with the knowledge is key to making things work.
Bottom line, reloading for gas guns is not as cut and dried as reloading for most other popular cartridges.
So I’m back to “small base for every new barrel”.
