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Posted: 3/9/2013 5:59:58 PM EDT
| I just acquired a colt marked upper, no charging handle or BCG, with the triangle handguards, no shell deflector, but it does have the L shaped forward assist. I brought it home and checked to see if my Colt HBAR's bolt would fit it, but it won't go into battery at all, Tried a LE-6920 bolt and same issue. Did these uppers have their own bolt system? does anyone know how to fins such a thing if it does? Thanks for any help. |
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I just acquired a colt marked upper, no charging handle or BCG, with the triangle handguards, no shell deflector, but it does have the L shaped forward assist. I brought it home and checked to see if my Colt HBAR's bolt would fit it, but it won't go into battery at all, Tried a LE-6920 bolt and same issue. Did these uppers have their own bolt system? does anyone know how to fins such a thing if it does? Thanks for any help. remove the bolt and see if you can get the carrier to slide in fully. if it won't, your gas tube may be tweaked a little not allowing the gas tube to sit in the gas key. outside of the professional ordnance carbon 15 pre-bushmaster, everyone uses the same barrel extension so ar15 bolts can be used. |
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that does seem to be the problem, the gas tube is pretty far back into the reciever, is there a reason it would be pushed back this far? Thanks for the help if the gas tube is sticking into the receiver further than your other uppers, there's a chance it's not pinned at the front sight base. they may have inserted the roll pin but it may not be through the gas tube which is preventing the gas tube from seating making it stick out too long into your receiver which means it's hitting the gas key and preventing your bolt carrier group from seating. see if you can move the gas tube with the handguards off. if you can move it, drive out the roll pin, seat the gas tube and reinsert the roll pin. |
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that does seem to be the problem, the gas tube is pretty far back into the reciever, is there a reason it would be pushed back this far? Thanks for the help if the gas tube is sticking into the receiver further than your other uppers, there's a chance it's not pinned at the front sight base. they may have inserted the roll pin but it may not be through the gas tube which is preventing the gas tube from seating making it stick out too long into your receiver which means it's hitting the gas key and preventing your bolt carrier group from seating. see if you can move the gas tube with the handguards off. if you can move it, drive out the roll pin, seat the gas tube and reinsert the roll pin. Thats a BINGO! 
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that does seem to be the problem, the gas tube is pretty far back into the reciever, is there a reason it would be pushed back this far? Thanks for the help if the gas tube is sticking into the receiver further than your other uppers, there's a chance it's not pinned at the front sight base. they may have inserted the roll pin but it may not be through the gas tube which is preventing the gas tube from seating making it stick out too long into your receiver which means it's hitting the gas key and preventing your bolt carrier group from seating. see if you can move the gas tube with the handguards off. if you can move it, drive out the roll pin, seat the gas tube and reinsert the roll pin. Thats a BINGO! Funny how often that is seen! 
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that does seem to be the problem, the gas tube is pretty far back into the reciever, is there a reason it would be pushed back this far? Thanks for the help if the gas tube is sticking into the receiver further than your other uppers, there's a chance it's not pinned at the front sight base. they may have inserted the roll pin but it may not be through the gas tube which is preventing the gas tube from seating making it stick out too long into your receiver which means it's hitting the gas key and preventing your bolt carrier group from seating. see if you can move the gas tube with the handguards off. if you can move it, drive out the roll pin, seat the gas tube and reinsert the roll pin. Thats a BINGO! Funny how often that is seen!
No joke. Here's another semi-common one. I just got a nice early 604 upper back around the first. Was oiling it down and happened to bump the gas tube which I felt was relatively pliable. Dang barrel nut wasn't torqued down. |
| Thanks for the advice, I guess I'll have to take it to my gunsmith, I don't have the tools or steady hand to ammend this. other question, if this upper has the forward assist but no shell deflector is there a chance it's a military surplus model and not an SP1? all the SP1's I've seen are slick sided, thats why I ask. |
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Thanks for the advice, I guess I'll have to take it to my gunsmith, I don't have the tools or steady hand to ammend this. other question, if this upper has the forward assist but no shell deflector is there a chance it's a military surplus model and not an SP1? all the SP1's I've seen are slick sided, thats why I ask. No SP1's came with a forward assist, so if it's marked with Colt proofs I'd say it probably USGI. |
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Thanks for the advice, I guess I'll have to take it to my gunsmith, I don't have the tools or steady hand to ammend this. other question, if this upper has the forward assist but no shell deflector is there a chance it's a military surplus model and not an SP1? all the SP1's I've seen are slick sided, thats why I ask. No SP1's came with a forward assist, so if it's marked with Colt proofs I'd say it probably USGI. also, did not all the SP1's usse a 5/16" frt take down pin? and all the mil. uppers would have been/are 1/4"? |
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Don't need many tools if someone just missed the gas tube with the roll pin. Need a small roll pin punch and a hammer. As stated if the gas tube will slide rearward out of the FSB then that's what happened more than likely. Think I'd check the hometown section at top of page and see if a member is close by. Make a new friend and fix your rifle. Although I doubt if most smith's would charge for this remedy. Personally I believe anyone venturing into the world of AR-15's especially retro should spend on a set of roll pin punches and everyone should own a hammer.
Reason I say this is necessary with retro is due to parts scarcity and the addiction that comes with owning one AR rifle that soon multiplies to a few different builds for many different circumstances. It's not uncommon for me to install a part that isn't retro correct but more than functional until I find the desired correct part. This way I can enjoy shooting my build, while enjoying the search for that special sometimes unobtainum part. Not much on an AR that can't be swapped out in 5 minutes taking your time. First retro I built took me 3 months to gather parts and less than an hour to assemble going slow and meticulous. Back then retro parts were readily available and 1/4th the cost of current production parts. It took me the three months just to have the spare change. Bet I had $450 in the complete build. A retro build said you wanted something light weight and couldn't afford a store bought AR a few years back. We used to build them just to see how light we could make one or how little we could spend on something close to 1 MOA. The good ole days! |
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