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Posted: 11/6/2011 5:43:59 PM EDT
| I'm not sure if this is considered a failure to eject or not. I got a cheapo FrankinUpper. I put it on a lower I already have. It came with a Spikes .22 conversion kit. I dumped three mags of the .22 through it and it cycled really well. Not a single malfunction. I then put a new SA BCG in it. It chambers the round fine and fires but the bolt doesn't cycle back at all. I'm not seeing any movement in the BCG after firing the one shot. I did this 5x trying 3 different magazines. It's like there is no exhaust pushing the bolt back at all. But the .22 kit cycles fine. |
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The 22lr uses blow back to just push the bolt back, while the 223 used a gas system to unlock the bolt.
Best guess, the gas system in the barrel is plugged with lead, and will need to be cleaned. To confirm this, just try to blow through the back of the gas tube in the receiver with a piece of tubing. And why does this happen, the lead 22lr scrap off a bit of lead as it passes past the barrel gas port, and this sliver each time build up in the forward gas parts to clog them. If the gas tube, FSB passage, and barrel port are lead clogged, then you will need to pull the gas tube and FSB to clean all the leading out of such. |
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Thanks for the reply Dano.
Sure enough, I blew through the end of the gas tube and it is extremely difficult to put any air through it. The previous owner of the frankinUpper said he just used it for a designated .22 upper which would explane the lead plogging. This will definately be a learning experience for me since I've never had to take apart an upper before. I've put together a number of lowers but this one will be new. I knew the upper was in bad shape but the price was still right. I'm just not sure it's worth taking it apart for me. It's got this beat up free-float quad rail that looks like it was kryloned over. It sits about an 1/8" above the rail on the upper receiver. The barrel nut has scrapes all over it from someone else taking it apart. I suppose If I'm going to practice taking apart a complete upper receiver this would be the one to chew up. |
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