I have never assembled a dedicated .22lr upper and would like to build one that is as accurate as possible.  

Would I go about this the same way as a centerfire AR? By that I mean heavier profile barrel, free floated with a good crown, drop in trigger, etc.

Does the collar and bolt system need improved? Is there a match version?

The only real consideration is I have lots of Black Dog mags so that is the pattern I would like to stay with.

I’m certainly no expert but I would be very surprised if you could do better than a CLE upper.

https://compasslake.com/product-category-hide/complete-upper/22-dedicated-uppers-complete-upper/

My upper is built with the CMMG 22LR 20" barrel and bolt.  I put it on my service rifle lower to shoot CMP rimfire sporter matches.  It will hold the X-ring (1" diameter) on a B-19 target at 50 yards.  It is not as accurate as the Compass Lake barrel but it is considerably cheaper.

I don't know anything about Rock River's .22 guns but I do know they are at least six months behind on 'run of the mill' AR15s and their current production is focused on those guns.  I ordered a left-hand AR for a customer in October and was told it won't even hit the shop floor until they fill their existing orders.

The Rock River Arms uses a Nordic Components pattern bolt.   The RRA upper will not work with the Booney Packer Better Mag Adapter and S&W 15-22 mags to get a fully functional bolt catch.   Rock River Arms uses Wilson Arms barrels which get good reviews.

The heart of a rimfire accuracy is a good barrel, good ammo.   CLE, JP, Beyer’s and Lothar Walther barrels get good reviews.   The Black Dog Machine and CMMG mags have been reliable for me but you can’t lock the bolt back like a centerfire AR-15.  The BDM/CMMG mags utilize a bolt hold open follower which holds the bolt open on the last shot out of the mag.  Pull the mag out of the well and the bolt closes.

Nordic uppers get good reviews on accuracy but I have no experience with Tippman.   The S&W 15-22 polymer upper and lower are not known for top accuracy.

True, but neither is strictly inclusive to the other.  I have had good barrels that shoot remarkably well with cheap ammo and vice-versa.  And not all good ammo will shoot the same in different quality barrels.  It is a moving target, and the same ammo can shoot differently lot to lot.  I have friends that are serious about it and when they get a case of ammo that shoots particularly well they will hunt the world over looking for the same lot number, and money is no object.

Probably the easiest and most cost-effective way to get into an accurate AR22 is to get a CMMG Bolt/Collar and either a Beyer Barrel or Lothar Walther Barrel.  These bolts have been tried and tested and work very well.  At the end of the day, the collar has nothing to do with accuracy.  A good barrel, good ammo, and good trigger will get you what you seek.  Compass Lake Engineering 22 uppers are considered by many the top of the heap.  They are expensive but I'm sure you won't regret it.  They do use different magazines though because he uses the M261 style conversion bolt.  Keystone accuracy does something similar to CLE but he uses the CMMG bolt to start with and I think he's currently backed up with bolt actions.  He's told a couple folks I'm aware of that he's not making the uppers right now.  RRA, Nordic, and JP all use the Nordic bolt and are know for great reliability and better than average accuracy but good luck getting your hands on one.  The Kriss Defiance AR22 (if you can find one) is very interesting in that it uses an adapter to use 10/22 barrels.  That opens up a larger array of barrel availability.  Don't expect Vudoo level accuracy but AR22s can be made to shoot very well.

If you want to be able to lock the bolt back with a CMMG pattern bolt and CMMG/BDM magazines you can use a Catch 22 version 1 or version 2.   Some ranges require you lock the action open or use a chamber flag so the Catch 22 is very handy.  The Catch 22 version 2 is easily removable if your still using the lower for centerfire uppers.

I rarely shoot on a public range and have no problem using the CMMG or BDM magazines with my 22 conversions or dedicated 22 rimfire AR-15’s.

Catch 22 web site has links to videos and shows how each magazine style work with each style conversion bolt with their products.


https://arcatch22.com

these mods were for a Sportsman's Team Challenge 10/22, but some most likely apply.... most came from Ken Tapp and David Tubb through conversations over the 5 seasons I was able to participate...basic rifle was Ruger receiver and bolt with a Clark fluted .920 barrel... Tasco 6-24x44 AO with 1/8 min clicks and 1/8min cross hair dot

as the 10/22 had an aluminum receiver, Ken Tapp recommended not to free float, but to completely bed the heavy barrel... I added a second forward mounting screw, the boss was divetailed to the barrel, not needed with AR

first year had problems with scope mounts loosening, so team cantilevered the mount off the barrel (not a problem with the AR and 1913 rail

reducing headspace of the bolt... recommended by David Tubb..., and build a drop check gauge to determine the rim thickness of your ammo... separate match ammo by head space... we were too cheap to buy Federal Gold Match or 900 with the dimple bottom to better distribute the priming compound (at the exorbitant cost of 10 cents a piece)

I encountered some first round flyers associated with pretty good following groups... by limiting the vertical movement of the firing pin, the problem was solved... a stop was TiG welded over the firing pin

the most dramatic improvement came with the addition of a harmonic barrel tuner... basically a relative finely adjustable weight attached to the muzzle to find the zero movement node of your barrel... which is basically the same as tuning your barrel to your ammunition, rather than searching for the ammunition that shoots best in your barrel... my DIY tuner (even on the thick barrel) could be incrementally moved... the 100yd shot groups would actually increase and decrease as the tuner was moved... mine was a piece of 1 1/4 aluminum round stock about 2" long, bored through to fit the barrel and held with a length wise saw slit and cross wise pinch bolt... one for an AR most likely a solid muzzle attachment... I like something with about .270" thru hole

with the above modifications, on a windless day off a rest, my 10/22 would shoot 10 shot groups with high velocity Winchester Super X into a 15/16 IPSC paster with more than random occurrence...we understood that the high velocity ammo that was crossing the speed of sound twice during the shot would be inherently less accurate than sub sonic ammo, but needed the additional velocity to knock down the steel targets at 90yd...a 1 1/2" or so star at 90yd is hard enough to hit off hand standing, to not have it fall over when you do

These are some of the issues that got me away from 10/22s.  Putting together an accurate AR seems a lot simpler.



Emphasis added.  This isn't what the OP requested, but it is what he should know.  Tacsol uppers are neat, but what would you do for spare parts.  Nordic/JE/RRA seem to me to be better thought out in several ways, but that doesn't matter if they won't send you parts as needed.

The CMMG pattern is very far from perfect, but there are a healthy handful of companies who sell parts at reasonable prices.  Betamax may have been superior to VHS, but ubiquity is important too.

I recently picked up a tacsol bolt and barrel on the used market and it's a nice system.  Once something breaks, parts will be hard to come by.  I have no idea what the original MSRP or production numbers on these things were, but I can't imagine it was cheap and that there were more than a handful made.

The CMMG system has flaws, but they can be tuned away with the right combo of parts.  My CMMG based uppers are more reliable than basically any other semi 22lr I have ever used.  They just run, and malfunctions are essentially non-existent.  As always, YMMV.

You can even make a Chiappa 22 upper shoot well if you want to. I have one that shot poorly until I threw away the polymer upper and replaced it with an aluminum upper. I also switched to free float handguards too which helped. I was pleasantly surprised by the accuracy of the Chiappa barrel once I switched out the upper receiver and handguards.