I wanted to see everyone's take on a .22 conversion for the AR-15 whether it is a conversion kit or a dedicated upper.

I'd go dedicated upper myself.

The conversion kits tend to shoot VERY dirty and can cause unnecessary wear and tear on your upper.

It seems like a dedicated upper is the better choice, but what type of wear usually occurs with a conversion kit? Also, do you recommend any companies that prefer dedicated upper or conversion kit over another? I'm leaning towards the conversion; just for practicing with my AR and not having to build an upper to replicate mine. With today's ammo prices, I'm not sure how long I can go.

It's my understanding that the kits can cause excessive leading in the barrel. There are a ton of kits out there from several manufacturers. The ones I hear about most often are Ciener, DPMS, and CMMG. I'd rather have a dedicated upper, but there are a ton of folks that use the conversion kits.

First I'd check to see whether or not the kits will work with your piston system. The .22lr rounds generate much lower pressures.

I have a CMMG kit. I only use the plated bulk (Federal I think) ammo and the barrel stays fairly clean that way. I like the kit but would eventually like a dedicated upper.