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Posted: 7/29/2026 9:19:15 PM EDT
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Hello all, I want something to practice highpower offhand with and I've been looking at the Rock River NMA4. Has anyone here got experience with these? Do you think it is a decent/accurate enough upper for this purpose? Thanks for any input. Monte |
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Rock River Arms used to use Wilson Arms (OEM barrel maker from CT) air gauged stainless steel barrels. I have been around several of these RRA 223/5.56 stainless steel barrels and they were accurate. From reports I’ve read the RRA stainless steel rimfire barrels use a Sporter chamber and not a match chamber like Bentz. The RRA use a Nordic Components pattern bolt and Black Dog Machine/CMMG pattern AR-22 magazines. For service rifle position shooting trainer the RRA Match 22 LR probably has sufficient accuracy for shooting at 25 to 50 yards. There are a few members on rimfire central forum that own the RRA 22 LR AR-15. Most posters appear to like their RRA 22 rimfire rifles. Borebuddy is selling upgrade barrels from Green Mountain and Lilja that you might consider if you are wanting top accuracy. In rimfire match rifles it is generally assumed you’re going to have to use premium ammunition to get better to best accuracy. For a DCM, Service Rifle trainer shooting CCI standard velocity ammo at 25-50 yards I think a person could get some valuable trigger time. It might boil down to your intended purpose and how much you are willing to spend. After looking at Borebuddy I see the Lilja is listed with a 24” barrel. Green Mountain barrels are only listed in 24” an 18.5” lengths. Borebuddy sell an Apogee barrel in CMV that is 21” that will provide the same length as a 20” centerfire barrel. A rimfire barrel sits deeper in an AR-15 receiver so a 21” barrel could be used in a service rifle training rifle. I’ve considered the BB Apogee 21” barrel for 20” A-2 pattern AR-15 but just never got around to assembling one. https://borebuddy.com/product/borebuddy-apogee-match/ |
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The Nordic/RRA pattern barrels have a different barrel shank or extension for adapting 22 LR bolts. The Nordic/RRA pattern use a type of barrel collar with an attached ejector. The CMMG/Ciener pattern barrels use a .460” stub where the bolt collar slides onto the barrel stub. The CMMG collar incorporates a barrel feed ramp and is held in alignment to the bolt face with guide rails. The Nordic bolt fits flush up against the end of the barrel and is not physically held to the barrel. I’ll post a couple pictures showing the difference. Here is a picture of a stainless steel CMMG 22 LR bolt with barrel collar.  Here is a picture of a schematic of Nordic pattern bolt and barrel. 
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Here is a picture of a disassembled Nordic bolt. I can’t remember where I got this photo of a 22 LR barrel and bolt assembly. The Nordic pattern bolt and barrel are very similar and you can see the difference in how the bolt would mate up to the end of the barrel.  Here is a picture of two barrels with the barrel stub that accept the CMMG style of collar. 
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lol I laughed so hard when I saw your post on RF central. It’ll be the 2nd coming of the purse swinging apocalypse! The concern I had was it was a sporting chamber vs a Bentz. I guess I was wrong in thinking what was being marketed as more of a training/competition rifle should have a little better chamber than a pinker. |
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