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Posted: 8/2/2012 11:47:02 PM EDT
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Hello all,
I have an RRA 9mm build using all RRA parts in an RRA 9mm marked standard lower. I am using an RRA magazine block and I fire it entirely suppressed with a pistol can on it. After 300 rounds fired, the bolt hold part of the mag block was seized. It is a roll pin that holds the bolt hold adapter piece in the block. RRA didn't know this. So I figured I'd put this out there so somebody can find it. That pin is very well peened in place and required some good hammering to get out with my little brass hammer. The bolt hold adapter piece in the block was very rough and the hole for the roll pin had some material left from a dull bit to help the binding. The adapter piece had what I'll call "cast flashing" which looked like the remnants from injection molding of plastic where the little nozzles shoot the plastic. Yep, I know nothing about cast steel. I cleaned up that flashing roughly with a drill bit. Then I hit the thing with 200(220? 225? I forget.) sandpaper, finishing with 400 grit. I decided not to bother polishing it yet. I also ran a drill bit through the pin hole slowly by hand to remove most of the extra material in there. Then I ran sandpaper down the channel the bolt hold adapter sat in, again finishing in 400 grit. I used a piece of paper towel to tell when it was "smooth enough" in there to stop grabbing and tearing. I hit the actual bolt hold piece of the rifle with 400 grit because I had it out. Then I blasted everything with Rem Oil, cleaned that off, and Militec1-ed all those parts and their channels. Full function has returned to the LRBHO, and it works far better than it did from the factory. The parts actually move freely. I assume anybody else with a suppressed 9mm AR-15 and an RRA magazine block adapter can benefit from this information. You may want to punch that pin, and clean up all those surfaces. Well inside of 1000 rounds I'll decide if I did a good enough job. Oh, and FYI I am using CProducts magazines and they are awesome. Their plastic magazine block I bought broke coming out of the package. It was weaker than tissue paper. Like one of those tiny candy canes that breaks when you try to peel the wrapper off. Except weaker. I'm not exaggerating. This issue rarely, if ever gets mentioned on here. So I figured I'd help somebody out that is trying to find information like I have a couple times Making it easy to find: Rock River Arms RRA Magazine Mag Block Adapter LRBHO Seize Seized Stuck Jammed bolt doesn't lock back 9mm NATO 9x19mm |
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Blocks that have a BHO actuator in them are always going to be more susceptible to problems if the actuator cannot move freely.
Hahn has revised their blocks with BHO many times to try to make them more reliable. Crud from the blowback action can still build up if not cleaned and cause the BHO actuator to stick or not move smoothly/freely. The best BHO option is a block without an actuator that uses the long finger 9mm specific bolt catch. It has less moving parts and does not need to be cleaned as frequently to ensure trouble free BHO operation. KISS - less parts are always better. With that said, those that want quick change capability will be stuck using a bottom load block with a BHO actuator and will need to verify smooth operation of the BHO actuator and check and clean that area as needed to ensure smooth, trouble free operation. This information is not really new. The problem with out of spec machining and/or poor QC that requires clean up is also, unfortunately, not new. Sorry to hear you had to clean up an RRA block, but that stuff does happen from time to time. Another thing to watch for on old blocks is ejectors that are not pinned. They can rub against the BHO actuator and cause it to bind. Most of the newer Hahn blocks (within the last couple years) now have ejectors secured by pins/screws so the BHO actuator can move freely without interference. |
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Who makes the block(s?) that utilizes a single piece bolt hold? Having 2 fewer parts (4 instead of 6 total) in the assembly would be a lot, lot better. Ignoring how much more reliable that would be and how much less friction is involved, the cleaning would be 100 times easier.
~One roll pin instead of two ~No need to remove the mag block every 300 rounds and then realign it for an hour, wasting ammo ~No need to take out that stupid mag block that you probably can't get spare parts for ~No need to work on that stupid mag block that RRA knows nothing about Also, yes, I am sure that it is not new for this kind of stuff to happen and is known issue with guys that already have a 9mm AR and have wrung it out and see all the drawbacks to attempting this. I did it because I lived in Connecticut and there were very few 9mm carbines available there due to illegal laws. So I dealt with the bolt speed and extremely large, expensive, and complicated beast that is the 9mm AR. I bet the average 9mm AR weighs a full two pounds more than any other 9mm carbine, or 30%, and has 50% more parts and 50% more cost. |
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