Hey Buzz.  Why .22LR?  Number one, they're cheap to feed.  Number two, don't sell the long-range capability of the lowly .22LR short...Several of us have these inserts (mine is the Crossno version).  I mainly compete in BPCR Silhouette, and I can tell you that the 200m chickens are boringly easy to hit with a .22, as are the 300m pigs.  The 385m turkeys are a bit more of a challenge, but on a calm evening can be hit with amazing regularity.

As for reaming one to .22 Magnum, I'd recommend checking with the respective manufacturer.  After all, they're just made from .22LR barrel liners.

Greg

Les,

Go with the Crossno, you won't be disappointed in it's accuracy.  Mine will do 1" to 1 1/2" groups at 100 yds with several brands of ammunition.  Some of the really cheap stuff shoots pretty darn well, which is nice.

>>>(E8 I presume?) <<< Guilty as charged...retired 1SG, Army type, one each.

Greg

Should make for some raised eyebrows when I haul it out to shoot crows with my friends   
Multi-use gun.  Might be I made a better (practical) purchase than I thought - I always kind of liked Sharps rifles, and just happened to be in the shop when the original owner came in with it. He got "Quiglyfied" and ordered it, then never shot it. Upgraded wood, long range sights and the works. Grabbed it on the spot for a very good price. It's going to Africa with me in September also. 
Do you find the converters are as picky when it comes to ammo as "normal" .22's?

(USMC here, med retired E-7 after 16)

Thanks Boats, will give the ely's a go, in fact, I've got some around here somewhere...

While I'm waiting for the liner, Question:  is there some sort of difficulty / problem with extracting the .22's? I seem to remember someone saying you need to pry them out with a screwdriver or something.

Buzz:  Go with the Crossno .22 liner.. They shoot great, but just be sure to shoot it enough till it takes a set in your rifle.  As you get to this point, the rifle will continually improve as to groups.  Then pick the ammo that seems to work best.  I have found the Winchester Dynapoints pretty darn good from K-Mart....

Michael,

Your Crossno liner will come with instructions.  You will need to lightly lube it, and the rotational position (think clock face) may affect the point of impact.  By experimenting with it you should be able to center the POI without much windage adjustment.  You will also find that when you insert the liner, as you push it in it will rotate with the rifling, so you need to take that into account to make it end up where you want.  It is easy to install and remove, easier than it sounds telling about it.  You don't need to worry about headspace, as the chamber end of the liner is fixed in a .45-70 case, so it just seats on the case rim.  You just push it out with a plastic rod from the muzzle.

Also, read what iowa wrote.

Paul