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Posted: 7/2/2008 3:51:33 PM EDT
| Just completed my 9mm build and have a problem. After the build I started a function check…checking just like an AR(that is all I know) The prob is once I pull the trigger and the hammer falls, the weapon is locked into battery. When the hammer is cocked the bolt carrier moves just like it should. No matter how hard I pull the charging handle the bolt carrier will not move. I can disassemble the weapon and the hammer is easily cocked and the bolt carrier and charging handle move freely. I even removed the magwell block and still have the same problem. I there something about the 9mm I don’t know? PLEASE HELP????? |
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What type of hammer do you have installed? If you have a standard AR15 hammer with the square notch in the top of the hammer face it will lock up the action just like you described. You need either a 9mm hammer or an M16 hammer with the disconnector release ground off. Check the 9mm FAQs and see if you have the right hammer. G |
I agree with Gee_Wizz, it sounds like a hammer problem, although I believe he meant you need the hook that engages the auto-sear ground off if using an M-16 hammer. Just to be sure though, what type of conversion are you running, RRA/Colt or Olympic? What model hammer are you using? Is your bolt ramped? |
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Thanks guys for the response. To the best of my figuring it is a hammer/bolt problem. I have tried with the magwell block removed and with the buffer tube removed and it will still lock up. I hate to sound dumb, but I have no idea the brands on the parts. A shop where my parents live went out of business and a guy bought the entire store and I purchased the magwell block, barrel(w/ A frame and handguards) bolt, hammer, 9mm buffer and spring for $350. He did not know for sure and I'm not savvy enough to look and be able to tell, I just thought it was a good deal. Anwway it seems the small notch on the front on the hammer is getting bound up with the bottom on the bolt just below the firing pin. I have attached pics, sorry but my camera does not take close-ups well. You can see by the pencil where I am talking about, the bolt already has some scaring??? in the area. Can I just do a lil filing on the hammer? Or just get a new hammer if so what brand? Really don’t want to have to drop $200 on a new bolt. BTW in a 9mm is it just called the bolt or still BCG? Thanks all for the help. C http://i291.photobucket.com/albums/ll300/UK_CATS_FAN/DSCN0465.jpg http://i291.photobucket.com/albums/ll300/UK_CATS_FAN/DSCN0466.jpg |
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Try taking the happer OUT of the lower. Put the receivers back together and try to cycle the bolt. If it cycles, then you KNOW it is a compatibility issue between the carrier and hammer. Then, simply take the receivers apart, put the hammer back into the lower. Holding your carrier in your hand above the lower (simulating as if it were inside the upper) push the carrier backwards over the hammer as in cycling the bolt. If you hold it propperly, you will be able to observe where the carrier is contacting the hammer and what issues it might have. |
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I installed a hammer from a Double Star LPK and the weapon cycles correctly. I have not fired live rounds yet, but it works with snap caps. I attacted a pic of the newlly installed hammer. I have read about the "ramped bolts" and differnet hammers, but still a lil unclear. Can I use the AR hammer with no damage to my lower receiver or bolt? Thanks http://i291.photobucket.com/albums/ll300/UK_CATS_FAN/DSCN0467.jpg |
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Usually, but not always, a notched hammer won't work with an unramped bolt. If it works for you consider yourself lucky and in the small minority. Since the dpms style hammer which doesn't have a notch will work for virtually everyone, thats usually the recommended starting point. This also allows you to swap uppers and convert back to 5.56 without changing hammers. On 9mm builds, we like to have the bolt "ramped" in order to cock the hammer over a longer period of time and longer distance of bolt travel, thereby reducing the hammer's rotational speed and tendency to slap. This reduces the likelihood of breaking hammer pins. Many of us install KNS Gen II pins also in 9mm AR's. |
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redcliff...thanks for the info. I measured how far back I have to pull the charging handle to reset the hammer and it is approx 1 1/2 to 1 3/4 inches. Is that ok? I know the pics are bad, but the bolt I have seems to be ramped to me, but it is the only one I have ever had "hands on" so I really dont know. Can you take a look for me. Also, what do the different pins do? Thanks C |
From the pictures it appears that your bolt is ramped. Here is a photo of my ramped 9mm bolt -- Ramped by ADCO.  My recommendation would still be to purchase a DPMS Hammer and install it. It is a semi hammer and does not have the notch. You may get a notched hammer to work, but the DPMS semi hammer is the standard solution that will work. Cost from Midway is about $16 to $18 plus shipping. Well worth it to be sure your 9mm will work. The KNS pins stop hammer and trigger pin rotation and thus reduces wear on the receiver. The pins themselves are stainless steel. Be sure and get the Generation II pins if you go this way.  Dave |
WOW another incorrectly ramped bolt |
Good question -- I am going to start a new topic just on ramped bolts pictures. Dave |
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