I have seen them on ebay for $200.
Do they work, is there a good place to purchase?
Is there a better brand to buy or a brand to avoid?

Thanks
(I thought I could take the ar to the pistol range)

$200 is too much.  don't buy gun stuff on ebay unless it's a really good deal, i've seen things on there go for double what their worth.  i have never tried a conversion but there are a couple kinds, the ceiner (sp?) which you can get 30rd mags for, and the army kit which the mag fits inside a usgi 20 or 30rd mag, they only hold 10 rounds though, no hi caps available with the army kit.  look on gunbroker.com or bushmaster has the ceiner kits on their site i believe.

www.bushmaster.com has the for abou $135 with 10rnd mag and $195 with 30rnd mag,  They work very, very well and are a hell of alot of fun!!  I have fired a friend's .22 conversion and never had any real problems.  Ocassionally a round wouldn't fire and the bolt doesn't stay open on last round fired, but that is minor.  

I plan to build one for myself soon.  When I do I will do what my friend did.  He used an old SP1 upper with the gas tube removed, on the other .22 rifle he had a dedicated AR upper built just for .22LR.  This way he doesn't have lead "blow back" and has the benifit of slower rifle twist (1/12).

In short...buy one...you'll love it.

Sgtar15

Thanks all,
That's what I needed to hear.
I didn't even think about lead foul.

I do not have one, but am in the process or purchasing the GI model.  I understand reliability is pretty good, and I like the fact that you use standard mags.  The mag inserts are cheap if you look around.

While some people have had problems with the Ceiner, it sounds like most people have good reliability.  Both the 10 and 30 rd mags are expensive.  KKF can make the mags look "normal" by welding a steel USA mag on the Ceiner mag.  As Ceiner itself apparently has bad customer service and you might be one of the few who gets a lemon, I'd buy one from Cabelas ($140) or someone else who guarantees product satisfaction.  

You can get 3 30 round mags for $150 direct from Ceiner, which is quite a bit better than anywhere else.

Most people who have conversions seem to wish they had bought one sooner.

Quoted: www.bushmaster.com has the for abou $135 with 10rnd mag and $195 with 30rnd mag Sgtar15

Check Shotgun News, They usually advertise the Ceiner kits witha 30 round mag for $179. Extra 30 round mags for $50-$60 I think. They are a lot of fun and a great way to use your AR at an indoor "Pistol Only" range.

The J. A. Ceiner 22LR conversion kits have always worked well for me too.

One thing (that's very important to me) Ceiner seems to pay particular attention to is getting the short sleeve on the insert just right.
I've used two from other manufacturers that didn't have the filler sleeve at all, the insert just ended at the front of the chamber shoulder.
That leaves a small gap (where the 223 cartridge neck would normally be), & a 22 has to jump a tiny space from the insert to,,, well all the way to the riffling.
It works OK.
BUT, when you try to switch back to 5.56 the shells won't fit because there's a ring of lead buildup.
Then you've got solid ½ hour of scrubbing to do!  





I've only bought them from Quality (so far):
www.bushmaster.com/shopping/accessories/jac-008.asp