Sent my factory built Rock River 9MM in for repair it had constant failures to eject.  And it would not work with the UZI or Colt magazine at all. They would not feed or extract. Before I sent it in the only mags that worked at all were the Pro mags. The pro mags would feed everything no problem but of course had failures to eject as well. Now that it is back it does work with the Uzi mags don’t know about Colt as I returned the expensive suckers and got a refund. But it will not feed JHP with the Pro Mags. The mag block came lose again so I re aligned it and tightened it back down hoping that would get the Pro Mages feeding no luck. Any suggestions on the Pro Mag and JHP? Also since returning the gun the bolt hold open barely works. With the bolt open if you lightly tap the gun without the magazine in the bolt slams forward. Is there a fix for that also? Also should I locktite the screw on the magazine block will that keep it in place. I hate to return it to the factory again. Will be out another thirty bucks in shipping plus it is a 30-mile round to my UPS counter. Would like to learn enough to fix these issues my self.

As far as feeding JHP, my RRA mag block would not feed them at all.  I switched to a Hahn mag block, and it feeds everything, no problem.  But, it does not work with Promags, only Colt and Uzi.  

To get my Promags to hold the bolt open (back before I threw them away in disgust) I had to use JB Weld to buld up the front of the follower in order for the follower to sit far enough back to trip the bolt catch.

As far as the bolt slamming forward after just bumping the rifle, mine does that to.  I think it is due to the lack of locking lugs on the bolt.  As far as I know, there is no fix.

If you want to feed JHP reliably, though, and have BHO reliably, here is what you need:

Hahn top loading dedicated mag block
Colt mags
Wolff mag springs.

Feeds everything, and locks the bolt back every time.  Downside:  Hahn block +1 Colt mag + 1 Wolff spring = $275.  It may not be worth it to you.  I hope all of this helps.

I have a 16" flat top RRA 9mm factory built rifle and it feeds most any ammo I run in it from 115gr to 147gr hollow points and FMJ. I use colt mags in mine. It has had maybe 3 jams in 800rds fired since new. My bushmaster 9mm ran flawless in about the same number or Rd's fired so I have been thinking of maybe replaceing the block with a hahn top loader,but I am not sure I will do it yet. My RRA block has never came loose yet and I removed it once to look it over good. It looks just like a copy the old colt SMG 9mm block to me. I like the way the hahns are grooved on top to help feed the rds I even considered machineing the RRA to match the hahn top grooves.

terry1
Whay JHP are you using? Just got back in from the range my flat top started jamming with the UZI magazines. Noticed the block had moved again. It just will not stay tight.  Moved the block back up and was feeding again. This gun will feed and eject FMJ all day but no luck with JHP.  I just don't understand why the pro mags worked and feed JHP now they will only feed FMJ. In my gun the accuracy with FMJ sucks.  Good thing I had two Rock River AR15 .223 with me so I had some fun. They are both tack drivers 100% reliable. That's why I got the RR 9MM figured it would be the same but I was wrong.

I mainly have fired 147gr Ranger SXT and 147gr XTP factory loaded hollow point ammo. I fired a limted about of 115gr XTP. My block has also stayed tight and does not move at all when it is put in and locked into place just with the lower 's mag latch. Then When you set the setscrew on bottem its a done deal and locked in place. My rifle is a new rifle only about 3 months old from the factory I wonder if RRA has changed  and improved of these parts do to probelms on older rifles/blocks? It seems some people have no problem while others have a nightmare trying to make things work. I would expect RRA to make it right but as you stated it's  pain in the butt to pack,send off,and pay shipping cost  while not haveing a rifle to shoot until the problem is fixed. I have mainly just used new colt 32rd mags in my RRA they work well but cost $55each so that sucks. I lost the factory 25rd UZI mag first week I had the rifle left it on the range never to be seen again. Never even used it one time. How is your block moveing does the factory lower  mag latch not lock it into place also?Mine fits so tight theres no movement even without the setscrew locked down. I don't see how mine could move even without the setscrew not locked down unless you release the mag then it would fall out . Also is yours a bottem loader block like mine or did RRA make a top loader also?

I'd think RRA would be picking up the tabs on shipping since you state it is a factory gun.

I too have a factory RRA 9mm and it's worked 100% although I have the exact bolt hold open issue that you describe.  I've corresponded with Steve, the RRA rep here on the site, and he advised to get an RMA to have it returned so they can diagnose the problem.

I'd look him up in the Industry section and see what he has to say, he's usually very quick to respond.

Good luck,
Scott

Rock River did not pay my shipping the first time.  I included a detailed letter with my return that I am not even sure they read.  When they returned my gun they forgot to send back the magazine I sent with it. I have already been in contact with Steve several times over this gun. After today’s range trip it just may go again.  If it does this time I will be asking for compensation on shipping. I have posted about my issues with this gun several times. It looks like I have the only one out there that doesn’t want to work.