I was talking to a bud in the gun club about his 222 Rem 700, manufacturing date 1964. He is having the thing rebarreled to 223 Rem. He claims the barrel twist is 1:14" on the 222 Rem. Both of us have shot outstanding scores, with AR's, with 1:8 barrels, and with 53 JHP bullets. Neither one of sees a reason to have a 1:14 twist barrel that won't shoot 69's, 75's, or 77's, when we can have a 1:8 twist barrel that will shoot sub MOA with 52gr, 53gr, through 80 grains bullets.
I do have Colt AR15 magazines stamped on the bottom "222 Remington" I purchased them during the first assault weapon ban, there will be another rolling around in the future, they feed 223 rounds just fine.