Advise on which of my Rifle cartridges I should learn to cast rifle boolits.

[rogn]

I spent a lot of time in the late 50s shooting anything I could load in a 222 Rem. I had a lovering design mold that I recall a 55gr and the gas checks were frustrating to deal with. I think a lot were shed in flight and my have impaired accuracy. The best I could accomplish was 3-4" at 100. Jacketed were very good. Since I have played with 7mm, 30, 375, and 45. The 7 and thirty shoot well with minimal preps and the 375 will shoot <moa. My early experiments were limited by my $ resources and much more limited powder primer choices. I guess I have to agree, the little guys are more finicky and the bigger ones are mor forgiving.

[gloob]

I would tend to cast for 243 first, from the perspective of cost. Jacketed 243 bullets can't be purchased particularly cheap.

From an accuracy-chasing standpoint, well, I don't really go there with my cast rifle loads, so I can't really add any experience from that perspective. My 223 gas checked bullets shoot good enough for my purposes.

In theory, your 22-250 should be able to shoot cast bullets at higher velocities than your 223, if that's a concern. Slower twist rate, and all. But in either case, I would favor somewhere between 50% and 100% lino for 223, if you want to shoot paper at long range, because you will be able to get higher velocities (less drift and drop).