As listed on the S&W website (and mentioned elsewhere), the 15-22 is a 1:15" twist rate.

I've mostly been using CCI Mini-Mag 40gr round nose so far in my new-ish 15-22 (DUR-series) without any notable issues. From what I've learned about the CCI ammo, it is definitely just a copper wash/plating (not a jacket)... and there is most definitely some sort of wax or other plastic-like sealant coating on the bullets, which you will notice if you handle the bullets while loading and get the residue on your warm fingers. Anyone know exactly what they use as their sealing material?

Some groupings from my efforts to to sight-in my RDS are decent enough at 25yds with the CCI 40gr:



Once I'm happy things are going well, I will probably try to switch to Federal Champion 36gr HP rounds since they are half the cost of the CCI Mini-Mag rounds.

From everything I've seen, I have little inclination to run non-copper plated ammo through the 15-22.

People who have been running CCI Stingers in your 15-22, are you sure it's not putting undue wear/tear on your internals? Even the built-like-a-tank Ruger Mk III pistol users warn us not to run HV ammo through the pistol as a routine due to the increased stress it places on all the mechanicals as it slams the bolt and stuff around. HV rounds are more reliable when put through a revolver and such, I believe.

Happy 15-22'ing!

edit: "HV" above refers to "hyper" velocity, not high-velocity like Mini-Mag or Federal Champion