It's all determined by case-head size. That's why a 308 winchester isn't safe in a Contender. The 444 and 45-70 are much larger heads but pressure is much less, even with hot handloads. 222 and 223 have been factory offerings forever. The Encore is safe with the belted mags of 375 Origination. No larger. Please read that this means the new larger Ultra mags, among others are unsafe. If JD Jones won't chamber one and shoot it, I won't either. Some 'custom' shops of nefarious nature are chambering the larger stuff. Rumor has it that the are stretching Encore frames. No small feat in itself. Load safe and have fun!
