Does anyone know what diameter the barrel is on a RRA 9MM upper where the front sight/gas block goes. I am considering getting one but would like to install a free float tube, perhaps this Hogue or a similar tube, but I would also like to replace the front sight with a 4 rail gas block, perhaps this DPMS, this AR-Stoner, or something similar.
The Rock River upper uses a standard HBar external profile. The diameter under the gas block is 0.750" so you can use pretty much any standard gas block you like. You can install just about any free float hand guard you like including a longer one (like a rifle length) and as already noted, install a front sight on top of that if you like. Also as already stated you do not "need" any gas block at all if you do not want one. On the 9mm it serves no gas function at all.
I am also thinking of "building" the lower. I am considering getting an Anvil Arms or Stag lower (price & good reviews), a parts kit of some kind (9MM compatible) and will need a buttstock/buffer tube/??? I kind of like the look of this Ace 4M Socom, but am open to suggestions.
We would be most pleased if you selected an anvil Arms receiver for your project!
You can use any stock you like, standard carbine spring but your going to need a 9mm buffer (They are very heavy, about 2-3x more than a standard buffer) because it is a blow back system, not a gas system.
If you are using a standard Rock River type bolt you will need a special 9mm hammer. If your using a "Ramped" Rock River type bolt (not available from RR, this is a custom after market modification that must be done in a special jig in a machine shop on the surface grinder) you can use a standard 5.56 hammer.
You will either need to use goofy magazines with welded pieces on them to fit the magazine well or something like the Hahn magazine well adapter to accommodate the standard Colt pattern magazines.
We stock all 3 types of the Hahn block and have some of the best steel (and stainless steel!) Colt pattern 9mm magazines currently made. The steel ones are $25 each, Stainless steel are $35 each and both are guaranteed to function perfectly.
One further thing to consider; You did not mention barrel length, if your using a barrel under 16" your building a pistol and must not use a shoulder stock and you must be using a "
Factory registered pistol receiver".
If I missed any of your questions, please drop me an email (at the address just below) and I'll be happy to answer them them for you.
Jon Kruger
President, Anvil Arms LLC
Lakeland, FL.
Lifetime NRA Member
863-398-4460
[email protected]
www.AnvilArms.com
