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Posted: 4/2/2009 4:16:39 AM EDT
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OK. Shoot me straight here.
I have reviewed the how to pages, links, and videos. I feel very confident in my mechanical aptitude. But, I have never installed a barrel on an upper. I have done other miscellaneous tasks with weapons and other widgets. Also, I have the AF TO/Army TM for the M16. I will get/have the needed jigs and tools. So, how difficult/large is the chore? Thanks, |
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Quoted:
OK. Shoot me straight here. I have reviewed the how to pages, links, and videos. I feel very confident in my mechanical aptitude. But, I have never installed a barrel on an upper. I have done other miscellaneous tasks with weapons and other widgets. Also, I have the AF TO/Army TM for the M16. I will get/have the needed jigs and tools. So, how difficult/large is the chore? Thanks, It is easy but, don't try it until you have the correct tools. You will need this action Block with insert. 
And a wrench like this. 
You will also need a 3/8" Torque wrench and some Moly grease(from auto parts store). Follow the TM. It also helps to wrap the upper with a sheet of paper to reduce marring on the sides of the receiver when tightening barrel nut. |
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Quoted:
Quoted:
OK. Shoot me straight here. I have reviewed the how to pages, links, and videos. I feel very confident in my mechanical aptitude. But, I have never installed a barrel on an upper. I have done other miscellaneous tasks with weapons and other widgets. Also, I have the AF TO/Army TM for the M16. I will get/have the needed jigs and tools. So, how difficult/large is the chore? Thanks, It is easy but, don't try it until you have the correct tools. You will need this action Block with insert.
And a wrench like this.
You will also need a 3/8" Torque wrench and some Moly grease(from auto parts store). Follow the TM. It also helps to wrap the upper with a sheet of paper to reduce marring on the sides of the receiver when tightening barrel nut. What he said. Grease... ask for "wheel bearing grease, disk brakes". The grease you need is NOT "Neverseize", or any other silver or copper colored goop that contains metal particles. You want a grease with molydisulfide. If not that, then ordinary grease like you would greast U-joints, etc. Grease gun grease. There is no magic torque figure where everything will align. There is just a minimum, 30 ft-lbs. A good, solidly mounted vise is essential. A 3" vise on a B&D Workmate is not going to cut it. 4" vise minimum, 5" is better, and bolted to a big, solid, heavy non moving work bench or vise pedistal. Don't use a "click" type torque wrench. Use a beam wrench. A "click" type wrench tells you where to stop, when you have reached a particular torque. That is not what we are doing here. All we want is a minimum, and whatever it takes above that. Torque it up to 30 ft-lbs and back off 3 or 4 times to smooth the threads. Now go for the gold. As you do this, push the barrel wrench into the barrel nut so the wrench does not slip and damage the teeth. If it aligns at 30, good to go, you are done. If not, stop. Remove the torque wrench (above 30 you don't need to know) and instead use a 1/2" breaker bar. Advance to alignment. Do not use barrel vise jaws for this job. Use barrel vise jaws for installing or removing flash hiders and other muzzle devices. I don't care if that is what they specify in the mil TM or that Bushmaster uses them. (Bushmaster is also famous for canted front sight bases... go figure.) And do not use the above pictured action block for flash hider work. Use barrel vise jaws for that. OK, say you get up to 80 ft-lb and it is almost, but not quite aligned. Back it off, try again. You will find it will move a little further each time. But you CAN achieve alignment on the first notch above 30 ft-lb. |
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.... OK, say you get up to 80 ft-lb and it is almost, but not quite aligned. Back it off, try again. You will find it will move a little further each time. But you CAN achieve alignment on the first notch above 30 ft-lb. The key here is exactly this. Don't force it if it doesn't align the first time. Just keep tightening and loosening until it aligns with reasonable force. |
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+1
I just did 3 today. 1st timed at 35ft Lbs, 2nd went to 69ft lbs but needed just a hair more to time it, loosened when back to 65ft lbs, just a little more, loosened, back up to 63ft lbs perfect timing. The 3rd one was about the same as #2, timing reached at 61 ft lbs. Did 2 a couple weeks ago, one timed at 34 the other at 74ft lbs. I have done others in the mid 40s and 50s so don't get concerned if you have to go a little higher, anything between 31-80 ft lbs is fine. On a side note, I usally have my friend apply just a little torque on the FSB opposite of the direction I am tightening, Just slight hand pressure. Not sure if it's doing anything but I do not have any canted FSBs  Every once in a while there will be a tiny bit of play on the receiver slot and the barrel index pin, I mean a tiny bit, I figure that the reverse torque is helping to keep the FSB straight up 12oclock.
I heard Colt and FN have a fixture that holds both the receiver and the barrel stationary to accomplish the same. My upper receiver clamshell clamp and a helper's hands are my special fixture. YMMV |
| To cure the little bit of play in the indexing pin slot and so that you dont end up with a mis indexed barrel a little piece of soda can aluminum cut in a tiny strip.Put in back of index pin as your seating the barrel and use a malet to tap the FSB on front to seat the barrel...nice and snug,no movement and perfectly straight.The rifle will zero within 3 to 5 clicks L or R when sighting in. |
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Quoted:
After you've done a few barrels, you'll get it down to a 10 minute job. Hell if you watch videos and read the guides a few times before your first one, you could probably do it in 15 min the first time. Assuming you're only talking about putting the barrel on (not the gas block and tube). |
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I heard Colt and FN have a fixture that holds both the receiver and the barrel stationary to accomplish the same. My upper receiver clamshell clamp and a helper's hands are my special fixture. YMMV
I was about to remove this image link, it appears it has been done for me. Sorry, Quib. |
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