If the rifle is not a salt wood gun as 2mg mentioned, and if the price is anywhere close to being good, buy the rifle, and treat it right. I have two rifles chambered for the 222 Mag. Each will deliver 5 shot, 1/2" accuracy at 100 yards. I think the 222 Mag is a tad better design then the standard 223, but there's not enough difference between the two to quibble over w/r to balistics
Brass is readily available from Huntingtons.come, RCBS. I just bought a bag of 250 pieces of 222 Mag brass from them about 3 weeks ago.
Also, Nosler makes custom loaded 222 Mag ammo for Midway. I bought a box of it before finding out that RCBS had brass available. That ammo Nosler makes is absolutely the most accurate factory ammo I ever shot. It's the ammo I shot two 1/2" five shot groups at 100 yards with each rifle I have, totaling four groups...
Martyn