In case you don't follow the wildcat section, there's a nice ongoing salon wondering about a suitable donor for a possible 5.45x39 to take advantage of the cheap commie ammo. The initial speculation was that a .22 Hornet would work.
There was some confusion on the bullet size, so I bought a paper pack out of a spam can at the gunshow today. A quick caliper check showed .219-.220 against some reference Prvi .223 I had on hand that ran .222-.223. We were wondering if the .22RF barrels were slightly smaller and would work as a donor, as many of the custom barrel makers show their .22RF as slightly smaller than the .223 offerings.
Any help is greatly appreciated.