I found nice Sig 226R this weekend for a good price and bought it. Is the lower frame for the 226R the same as for the standard 226 in 9mm? In other words, can I put a standard 226 9mm upper on it and have the equivalent of a standard 226 9mm?

Thanks for the imput!!!!

Yes. Sig offered conversion kits for this.

Sig makes caliber exchange kits or you can pick up a used upper. The 22lr frame is SA/DA, and a per Sig they won't convert it to DAK. I ended up getting a 226 DAK in 40 and everything intermixes.