I don't understand the idea that buying a .22 upper for an AR is a good idea. If you do buy another centerfire upper for the lower later on you will essentially be stuck without a lower for the rimfire. If you just buy a .22 to start with you'll always have that .22 and you won't be sharing parts between two rifles. What is most likely going to happen is that the rimfire upper will be tossed in a corner or in a box and you won't use it again because swapping back and forth will be a lot more hassle than you think.
If actually owned one you'd understand that swapping uppers requires about ten seconds to push out two pins, switch the uppers, and push the two pins back in.
I don't believe you can learn to shoot better using a rimfire upper either. From what I've heard the accuracy of those Frankenstein guns is not all that great compared to a regular .22.
So you have no actual experience .22 LR AR uppers. You're confused between a .22 LR conversion kit for a .223/5.56 upper, and a dedicated .22 LR upper. Conversion kits are simply a bolt carrier group with a chamber adapter that lets you send the .221 diameter .22 LR bullets down the .224 diameter .223/5.56 bore. In contrast, a dedicated .22 LR upper has a .22 LR chamber, and .221 diameter bore. A dedicated .22 LR AR-15 upper is just as accurate as any regular .22 LR rifle with equal quality barrels.
You can get a very good .22 for not a lot of money and you can have one that will always be complete. There's just no way I would try to share a lower for two different rifles. The price of an upper will be much higher than the price of a good semi-auto rimfire bought as a whole rifle. It just makes zero sense to me.
You probably don't get people buying rimfire barrels for T/C Contenders & Encores either. Those barrels cost more than a $160 base model Marlin rimfire too. Just like swapping uppers on an AR-15, T/C owners swap barrels on a receiver. It's not a new concept.
I do not see the point at all. If you just want a .22 that looks like an AR then yeah, go for it. But to actually learn to shoot you'll be MUCH better off buying a whole .22 rifle.
If you want to train with the same rifle you plan to use for defense it makes quite a bit of sense. If you look at AR-15 sights you'll see that most rear sights are target type aperture sights because they've evolved from the aperture sights on US service rifles. AR sights (in any caliber from .22 LR up) are typically much better than the flimsy notched blade on cheap .22s like the Marlin Model 60.
You can buy a very good semi-auto .22 for $160 - and that's the shipped price. How much does an upper conversion cost? The ones I looked at were over $550!. And you only get half a rifle? It makes absolutely no sense to me. You can get a fantastic .22 for that price and it will actually be accurate.
Again, I've addressed the accuracy issue above. You're assuming without any actual experience. Midway has a CMMG dedicated .22 LR AR upper in stock for $350, but you'll have to add the sights of your choice.
http://www.midwayusa.com/product/21...y-matte-with-m4-handguard-flash-hider-pre-ban. Notice that you're getting a WASP treated (black nitride - aka Tennifer, aka Melonite) barrel which provides extreme durability. That barrel is also threaded 1/2x28 RH so you can take off the flash hider and add any popular .22 caliber muzzle device. You also have a forged aluminum upper with Mil 1913 (aka Picatinny) rail. Trying to compare a quality .22 LR AR upper to a cheap Marlin rifle is an apples to peanuts comparison.
I did find an upper for $500 but that doesn't include shipping or an FFL fee. You can get a CZ 453 for that price which will shoot fantastic. No upper conversion is ever going to match it's accuracy and you get a whole rifle instead of half a rifle.
The fact that you think an AR upper requires an FFL fee further demonstrates your ignorance. An AR upper is just a part; the lower receiver is the serial numbered firearm that has to go through an FFL. I'd put a CMMG dedicated .22 LR upper against a CZ 453 any day. The accuracy will be much closer than you assume.
I've held off saying that for a long time but I just felt like it was time someone said it. It just passes as good advice without question too often and I can see a whole bunch of reasons not to do it.
If you believe in training with the rifle you fight with it's a great idea. If you like the AR-15's superior ergonomics, sights, and scope mounting options it's a great idea. If you like the capability to drop in a trigger like a Geissle SSA, that will go toe to toe with any match rifle trigger, without need of a gunsmith it's a great idea. If you like having a stock that can almost instantly adjust LOP to go from an adult to a 5 year old & back again it's a great idea. If you like the ability to switch stocks, grips, and forends to fit you perfectly without need of a gunsmith (in most cases) it's a great idea.
To each his own I guess but this is something that just baffles me. I guess it's black rifle fever or something. Nothing personal guys but I don't get it at all. Heck by the time you buy an upper and a bottom you could have bought an Anschutz, which is the best rimfire you can buy AFAIK. Instead you'll get a black rifle looking .22 that isn't as accurate as a Marlin 795, which can be bought for $100. I guess you have your reasons but I don't know what they are.
I hope that my comments above have dispelled the accuracy myth, and shown this isn't just a black rifle thing, but a practical concept for a variety of reasons. I do sincerely hope that my comments have at least allowed you to understand the reasoning behind a .22 LR AR upper. If black rifles aren't your thing that's totally cool with me, but hopefully my comments have helped you appreciate them more. Anschutz rifles aren't my thing, but I certainly appreciate them for their accuracy & craftsmanship.
In the interest of full disclosure a Marlin Model 60 was my first rifle & I still own it. I also own a T/C Contender, and have a .22 Mag rimfire bbl. for it too.