Winchester M-22 Subsonic Ammo is rated as 45 gr at 1090 fps.
http://www.winchester.com/library/news/Pages/new-winchester-m-22-subsonic.aspx
The M-22 is designed specifically to function in semi-automatic firearms, while remaining subsonic from both pistol and rifle length barrels. The new M-22 Subsonic features a 45-grain black-plated lead round nose bullet that has the equivalent energy of full velocity 36-grain rimfire products. In addition, the M-22 Subsonic utilizes non-corrosive priming and clean burning powder for reduced muzzle flash.
The M-22 Subsonic was also created with suppressed firearms in mind, but performs just as well in unsuppressed rifles and handguns. During Winchester testing, M-22 Subsonic rounds measured 129 dB from an unsuppressed rifle. That is significantly quieter than a full velocity .22 LR fired from a suppressed rifle, which typically measures around 138 db. With the addition of a suppressor, M-22 Subsonic achieves a remarkably quiet 116 db.