Any help from RRA 9mm carbine owners here would be greatly appreciated!
I purchased a Rock River Arms 9mm Carbine A4 9MM1222X and am trying to get some answers to questions that I could not obtain easily from RRA without taking time off work to call them during their business hours. There seems to be no info available on their website nor in the “manual” they ship which is actually a generic army ar-15 field manual.
My questions are these…
Which types of 9mm ammo CAN NOT be used safely with this carbine (eg. +P, bullet weights above 115gr, etc.) For example, it is not recommended to feed much 147gr into my Browning HP pistol - are there similar recommendations for this carbine?
Would Fiocchi 115gr FMJ be a good practice round for this carbine and Corbon DPX +P 115gr be a decent protection round?
If I attach an off-the-shelf reflex sight, will I need a Picatinny rail riser to raise the sight high enough to clear the front sight or co-witness with it? I assume so. Do I need to have the front sight removed?
Where can I get magazines for this carbine? The RRA website shows “modified for ar-use” and “unmodified” Uzi magazines for sale - it’s really not clear what’s going on. I read something about colt magazines being used?
If I want to attach a grip to the handguard (it has six holes on top and bottom but no picatinny rail) then how is it attached?
Please excuse my inexperience - this is my first AR and many of you are experts in buying receivers and lowers, putting it all together.
Which types of 9mm ammo CAN NOT be used safely with this carbine (eg. +P, bullet weights above 115gr, etc.) For example, it is not recommended to feed much 147gr into my Browning HP pistol - are there similar recommendations for this carbine?
You shouldn’t have any problems shooting +P loads or heavier bullets (such as 147 grainers) from your carbine. For especially hot loads, a heavy buffer like this one would help; I run a similar buffer in my 9mm carbines at all times even though I typically shoot normal 124 grain ball.
Would Fiocchi 115gr FMJ be a good practice round for this carbine and Corbon DPX +P 115gr be a decent protection round?
Any 115-124 grain ball would be fine for practice. I’d think the Corbon load you specified would be fine for defense, although you’ll likely get some additional penetration from the higher velocity afforded by your carbine’s longer (than pistol length) barrel. You might try a DPX load with a heavier bullet if possible.
If I attach an off-the-shelf reflex sight, will I need a Picatinny rail riser to raise the sight high enough to clear the front sight or co-witness with it? I assume so. Do I need to have the front sight removed?
I doubt you’ll find a practical mount tall enough to completely clear the front sight, nor would I think you’d want to. Typically folks run a red dot sight (RDS) with the iron sights cowitnessing in the lower third of the optic. You might try this mount and optic combination as an effective solution. As indicated by the graphic at the bottom of that page, the Tall mount will provide you with a lower-third cowitness with your iron sights. You don’t need to have the front sight removed, as you’ll likely not even notice it if you’re using the RDS correctly.
Where can I get magazines for this carbine? The RRA website shows “modified for ar-use” and “unmodified” Uzi magazines for sale - it’s really not clear what’s going on. I read something about colt magazines being used?
For use with their 9mm carbine, RRA sells modified Uzi magazines. Said modification involves the machining of a slot for the AR-style magazine catch, as the Uzi has a magazine catch slot that is smaller and closer to the base of the magazine. Unmodified Uzi magazines are just that – they have no extra slot machined for use with the AR-style magazine catch, so they won’t work with your 9mm carbine. You can find modified Uzi magazines at places like [ADCO Firearms](http://www.adcofirearms.com/acc/ProductLine_.cfm?product_category=Magazines/Accessories&subcategory=9mm Mags).
I’ve found that modified Uzi magazines work well in my 9mm ARs; they are relatively inexpensive, fairly easy to find, robust, and reliable. However, they typically do not provide a means for the bolt to be locked open on an empty magazine, so keep that in mind if you desire that feature. Magazines such as those manufactured by Metalform (the original manufacturer of “Colt” magazines) do provide a means for the bolt to be locked open on an empty magazine, but such magazines are typically more expensive than modified Uzi magazines. You can find Metalform magazines at places like Spike’s Tactical.
If I want to attach a grip to the handguard (it has six holes on top and bottom but no picatinny rail) then how is it attached?
An attachable rail such as these or this one should allow you to attach a grip in the manner you describe.
I do not have a RRA 9mm carbine however I do have the Beretta CX4 9mm—16.6" barrel. You’ll find Speer Gold Dot 124gr +p rounds are going to travel nearly 1400fps from the beretta, so I’d figure the same performance from your RRA. Corbon DPX breaks past 1400fps in the 125gr +P variety so I’d consider that your best defense round. Some 9mm carbines are shipped with 1:10 and others 1:15 barrel twists from what I remember so the 1:10 really stabilizes 147gr rds better. I don’t shoot my CX4 out past 50yd because I’ve only got my aimpoint on it, and usually not past 20yd. I think you’ll find that carbine to be a very fun shooter. I very much enjoy shooting my CX4, as it’s very light and handy. I pull out my Grendel when I want some long range fun.
