From what I've read the Atchisson (later sold to Ciener) and CMMG Atchisson pattern M16 .22 conversions were developed using Federal 36 gr., copper coated .22LR ammo. IIRC, the Vector conversion for the Uzi may have been as well.
I have a 2007 vintage Vector Uzi .22 conversion, several CMMG M16 .22 conversions and dedicated 4.5 in. and 9 in. uppers dating from as far back as 2010 and as recent as 2018, and a Fleming M11-380 .22 conversion that I bought used last year. All work well (unsuppressed as I don't have a full auto rated .22 silencer) with Federal 36, 38 and 40 gr., copper coated, CCI MiniMag, 40 gr., CCI ARTactical, 40 gr., and CCI SV, 40 gr. ammo, as well as others with projectiles in the 36-40 gr. range that are not sub sonic.
MHO, YMMV, etc.