I have an OEM Colt conversion kit that I've only tried out one time.  Does anyone happen to know which .22LR ammo brand/type shoot closest to the normal POI of the Colt Sporter HBAR upper?  (Not that I'll be likely to find a specific brand/type of .22LR very easily!)

Thanks for any suggestions,
Bob

For close range at 25 yards or less the 22 LR will still strike low just like centerfire 223/5.56.  When I used the 22 conversion the point of impact was close enough out to 50 yards for shooting steel plates.   I used a 100 yard zero for my 223/5.56 but for my dedicated 22 LR AR-15's I use a 50 yard zero.  A Friend used to shoot a lot of 22's in his Colt H-Bar with 1:9 twist.  He'd just raise his rear sight to hit at point of aim at 25 yards with 22 rimfire and just dialed it back to 3/6 setting for his 223/5.56 ammo.

I have had good luck with High Velocity 36-40 grain ammo, Federal 36 grain bulk, Aguilla 40 grain plated SE and CCI Mini Mags.  I don't use my Colt conversion much these days because I have several dedicated 22 AR-15's.   As with most 22 rimfires reliability may vary between brands of ammo or even a particulr lot/batch.  It is best to try a what is available and see how they shoot.  I usually prefer plated 22 LR with 22 conversions to help limit lead build up on flash hiders or in the gas system.