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Posted: 7/30/2010 7:24:55 PM EDT
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Hey guys...
Hoping for some help here... I just finished up my 1st build, but am having some problems with function testing. I'm running a BCM 14.5" middie with BCM bolt carrier group/handle on a Colt lower with Magpul UBR stock. The problem I'm having is that I cannot get the bolt/handle to move rearward for function testing. It seems as if the bolt carrier is not lined up with the buffer spring and won't budge. Both front and rear pivot pins are completely in place and no gap exists. I used the stock buffer spring/buffer (short) from my standard Colt stock. So...what is this newbie doing wrong? Very much appreciate your help! Thank you, BE |
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That sounds weird, now the old stock doesn't even work with it. Take a pic of the inside of the lower, like a top picture of the lower with no upper on. Hopefully we'll be able to see what it could be binding on.
And you said the upper is working fine too right, like you didn't leave out the firing pin or anything that could cause it to bind. |
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OK, so here is the update..
I removed the stock, buffer tube and spring and reassambled the upper and lower. Bolt moves fine without the stock installed. I then replaced the buffer tube without the buffer/spring and the bolt still refused to budge. As I mentioned earlier, I have a preban Colt lower and in fact it does have sear block on it. I'm thinking the sear block is somehow causing the mil-spec upper to not seat properly. Does anyone have experience with this? What is my next option? Thank you, BE |
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Do you have an M16 carrier? You can't use those in sear-blocked Colts. Otherwise, open the rifle and push the hammer down till it locks. Close it up, and see if you can work the bolt. You might just have a problem with your hammer spring not being installed properly. |
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Quoted:
Do you have an M16 carrier? You can't use those in sear-blocked Colts. Otherwise, open the rifle and push the hammer down till it locks. Close it up, and see if you can work the bolt. You might just have a problem with your hammer spring not being installed properly. The BCG is from Bravo Co. USA. So, yes, it's an M16 bcg. I guess I'll have to grind down or remove the block... BE |
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Quoted: Do you have an M16 carrier? You can't use those in sear-blocked Colts. Otherwise, open the rifle and push the hammer down till it locks. Close it up, and see if you can work the bolt. You might just have a problem with your hammer spring not being installed properly. When he said Colt lower thats the 1st thing I thought of. I think ADCO will remove the block from the lower for you. Might want to call and ask em what it would cost. Unless you have the ability to do it your self. |
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Yeah, easier said than done...I live in Massachusetts so we're still held to the AWB. It has to be a preban lower. you don't have to use a preban lower in Mass UNLESS you have a collapsible stock, a bayonet lug, or a FH. If you have a threaded barrel and put a compensator on it securely, use preban 20 or 30 round magazines, all readily available, and mount an RRA entry stock or an A1/A2 stock, your GTG then.....<><....:) |
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Quoted:
Quoted:
Yeah, easier said than done...I live in Massachusetts so we're still held to the AWB. It has to be a preban lower. you don't have to use a preban lower in Mass UNLESS you have a collapsible stock, a bayonet lug, or a FH. If you have a threaded barrel and put a compensator on it securely, use preban 20 or 30 round magazines, all readily available, and mount an RRA entry stock or an A1/A2 stock, your GTG then.....<><....:) Yes, I'm aware of that, but I'm using a collapsible stock and a FH on my upper already so I do need a pre-ban lower. When I said it had to be a preban lower I was referring to my specific build, not the law. Thanks, BE |
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II'm suprised you got the rear setent pin in with a full auto bolt and sear block. The full auto bolt is the only one that won't work with the block in place. I wouldn't remove the block I would just cut it down flush with the top surface of the lower. TX, Yes, that was my plan. Don't want to bother with removing the whole block if I don't plan on putting in a 2 stage trigger. Less work and less risk of damaging my pre-ban lower which demand quite a premium here in MA. The rear detent pin went in with only a little bit of resistence. It would of saved me a bunch of aggrevation if it didn't go in at all because then the sear block would of been more obvious. I probably only need to shave off about 1-2mm to get it to fit properly. BE |
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Update:
Got the sere block shaved down today just enough to work with my M16 BCG. My friend ended up breaking a carbide bit on his CNC machine on the 2nd pass (snapped right in half at 800 RPM). The sere block on the Colt is one tough mofo piece of hardened steel! We only shaved it down enough to allow the bolt carrier to work as opposed to the original plan of shaving it down flat to the reciever. It was just way too much work and didn't want him to break another tool. A little duracoat and it looks like it was never touched (besides the fact that the Colt logo is no more). Regardless, I wanted to thank everyone here for all the valuable info and input and for pointing me in the right direction. Great community! Regards, BE |
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