I'll 2nd steelslaver's suggestion but add one caution. Fire samples of the cartridges before buying 5,000. Ideally sample the inexpensive .22 cartridges available in local stores then go back to the store that sold you the cartridges that shot best in your gun. I once made the mistake of buying 10,000 or 15,000 of the same cartridges that my guns had been shooting well only to discover that they did not like the newer lot. Fortunately I was able to recover my money reselling them at the range. Many times big variety stores and sporting goods stores have had bricks of .22s that were about as inexpensive as I could get anywhere.

18s are excellent revolvers. If I did not have one I'd pay whatever I had to to get a good shooter.