Problem w/ Aluminum Case Blazer/Rock River

[FJR]

I recently purchased a brand new Rock River 9mm AR and I was having some problems during my first range trip. When I shoot Winchester White box 9mm ball ammo the rifle performed flawlessly. It even worked well with some brass cased hollowpoint ammunition of various makes. When I tried using Blazer 115 grain Aluminum cased ammo the rifle began to choke on every round. It would not fire more than one round and then it would suffer failure to eject malfunctions, some stovepipes, and sometimes it would double feed getting a live cartridge caught on the unextracted/ejected aluminum case. A friend has an older RRA 9mm rifle and his gun ran flawlessly on the Blazer. His rifle has an excellent track record with Blazer with thousands of rounds going through it without any major problems.

My rifle was well lubed and I could find no mechanical reason for it to malfunction like this. I briefly checked the extractor and ejector and all looked well. I will do a more detailed inspection when I clean it. I did notice that there were small scrapes on the case rim (from the extractor) that were similar, but maybe a little rougher, than the ones on the expended brass cases that I compared them to.

Has anyone had a similar experience or know of what I could do to make Blazer run in my gun? With ammo prices being what they are I would like to run this gun as cheaply as possible. Anything specific that I should look for when I break it down or is there anything I can do to make it more reliable with the Aluminum cased ammo? There was one other quality control issue with the rifle but it was unrelated to the problem with the ammo. Any advice is welcome. Thanks in advance.

[Robb Jensen]

Aluminum cased Blazer ammunition is a bad idea in any blowback operated firearm.

A co-workers Olympic 9mm had a casing of Blazer break off in the chamber............I warned him to not use it.

[eringobragh]

I had the exact same problems with my 9milly RRA and Blazer ammo (actually with a lot more ammo than just Blazer too!). Seemed really under powered, and the weapon didn't want to cycle fully, therefore leading to the problems you stated. Also I think my extractor tension was insufficient.

My rifle went back and forth to RRA three times before I finally got fed up and said F it and broke down and paid the extra cash for the real thing...a Colt 6450. This rifle has digested everything I have put through it...even the Blazers and UMCs. I was about to give up on the 9mm AR platform till I bought this Colt...now it's one of my favorite rifles to shoot!

I had thought about a reduced power buffer spring for the RRA...don't know if this would alleviate your issues or not? Also there's supposed to be an extractor roll pin fix to give more rim tension on RRA's?

[FJR]

Thanks for the replies. Erin, do you (or does anyone else know) if this "extractor roll pin fix" is similar to the CRANE extractor upgrade that is used for the 5.56 guns? If not, do you know what it entails? Thanks.

[Dave.O]

My Rock 9 won't shoot blazer aluminum either, but it will digest WWB, blazer brass, and wolf steel case.. since I know that, WWB is still in realm of being cheap to shoot.. still alot less that 5.56..

[eringobragh]

Never heard of the Crane upgrade...so can't help you there!?

I guess a bunch of the RRA 9mm bolts have a shitty rolled up metal pin...kind of like a Little Debbie "Swiss Cake Roll", and apparently this doesn't hold the extractor very firmly. I can't seem to find/remember the dimensions, but lurking around here or arfcom is the correct size for a split tension pin from your local hardware store that will supposedly/temporarily eliminate the problem.

The first two times mine went back to RRA, it still ran like crap. After the third time it ran for a couple hundred rounds then went downhill quickly again. I then switched to the split tension pin and things seemed great for about 600 to 800 rounds, then again went to crud. For the price of a split tension pin I should have just changed them out every 500 rounds or so, but I had already lost faith/confidence in the weapon, and had caught a really bad case of Colt fever...sold all seven of my sticks, and have been re-purchasing all Ponies!

Oh! One constant problem I also had with the RRA...the roll pin for the weight in the bolt/carrier would drift out with every firing! Every couple of mags I would have to pull the bolt and tap the pin back in because it would be scraping the inside of the upper receiver. RRA replaced it each time back as well, but the problem never went away...tried lock-tite too! Should have just used JB Weld!

[FJR]

Dave O.????

Is this the same Dave O. that hangs out with Choma-san? So your RRA shoots Wolf steel case huh? Maybe I will try some of that. It is nice and cheap.

Erin, thank you very much for that info. Now I have an idea on what to check out and keep an eye on. This is aggravating though, the sole reason I bought the RRA was because of how good my buddies had worked over several thousands of rounds. I was really considering a CMMG 9mm AR too, but I had not heard much aboput them.

I cannot use a Colt because I need a flat top AR. Too bad they do not make such a beast.

Thanks to all for their replies.


FJR

[eringobragh]

I cannot use a Colt because I need a flat top AR. Too bad they do not make such a beast.

FJR

I didn't let that stop me! Purchased a factory Colt A3 upper receiver from Brownell's and swapped the barrel over! Piece of cake! Runs like a Swiss clock!

http://img.photobucket.com/albums/v347/eringobragh/Wedding003.jpg

[FJR]

Nice job!

If they made those a standard rifle they would sell 3 times as many.............even at Colt prices!

[Dave.O]

FJR... That's me!!! This must be Mr Royce?

You have my cell # don't you? If not I will PM you with it.. I will tell you everything I did to make mine run real well, even with c-products mags...

[FJR]

PM inbond!

[eringobragh]

lurking around here or arfcom is the correct size for a split tension pin from your local hardware store that will supposedly/temporarily eliminate the problem.


Found it...⅛”x ¾”