Make sure you don't have a notch hammer I must be round or it will hang up on the carrier.

Welcome aboard!

Please clarify what you mean by "won't cycle at all". Manually or when firing? What magazines are you using? Did you clean and lubricate the upper and lower before you tested? (My factory RRA 9mm carbine came with minimal "preservative" on the bolt and inside the receiver, so I cleaned and lubed it well before even trying to function test it.)

You might want to hop over to the CMMG forum and read up on their 9mm lowers. They are made slightly different than the RRA and they do a bit of a different BHO than is used on the RRA.

I have both the CMMG and the RRA 9mm's. I had an unexplained wear mark on my bolt hold open latch until I learned there were some variations in the dimensions between the two. Now I have all the right bolts in the right guns and life is good. MY CMMG lower has been one very reliable and trouble free unit. I do run a CMMG bolt with the upper on that lower however. John Overstreet from CMMG wrote some about this back sometime last year. Try a search on "CMMG 9mm" and you might be able to find this info as he addressed this in their forum.

Also note that Rock River uses tolerances that make their receivers TIGHT when they mate upper to lower. It can take some breaking in to get things running smoothly.

I second this. This is your answer. It will work like a champ after this.

I can make a 9mm AR work, but I have no clue how to post pics! The BHO is the Bolt Hold Open (or bolt stop, bolt catch, or any of a half dozen correct or incorrect terms). If you are looking at the lower from above with the pistol grip in your hand and the mag well facing away from you, it will be that moving part just behind the mag well, with the "ping pong paddle" shaped lever sticking out the left side of the receiver. You want to take a small amount of material off the top of the right side. The area you need to remove is about 1/4" square, starting on the right side and moving inward. You only need to remove about 1/32" of depth.

If I can find the tutorial on posting pics, I'll see if I can post some.

I have the same setup. I can tell you that you will need to carefully take a little off the top of the BHO catch. I took too much off mine and didn't realize it until I bought some mags with BHO. I use modified UZI mags as they are super cheap and work.

Also, think about getting a RRA hammer and some KNS pins. You won't be sorry

My first outing with this showed me where I needed to remove some metal! There was a definite little wear mark. I wonder if you just hand cycled the bolt a few times if it wouldn't make this show up enough to know there to remove the material. I will have to dig out that lower and maybe get a picture of where the interference is.

To Kevin, if you're asking do I have a gunstore/gunsmith shop, the answer is no! Although I sometimes think I'm in the wrong line of work given my interests....