AR Sponsor
Posted: 2/25/2003 3:47:43 PM EDT
|
Is it safe for me to install a new barrel myself? Do I need to take it to a gunsmith? It is a colt barrel, and I have the barrel wrench. John |
|
FIRST, you need instructions. You need an "action block", not barrel vise jaws. Barrel wrench, either GI type or one of the fancier "armorer's tools". Standard, off-the-shelf automotive torque wrench with 1/2" drive. Moly grease (ordinary wheel bearing grease). Installing the pin for the gas tube... some say punches, but punches are for driving OUT pins, not for installing pins! Pins are PRESSED in. This is simple, use the largest vise-grip pliers you have, tape the jaws with electrical tape (to prevent scratching). Adjust the vise-grip so it just barely pushes on the pin, open it, turn the knob half a turn, press the pin in a little further. Open, half a turn on the knob, etc, repeat until the pin is all the way in. |
|
Stal: You might want to get a copy of USMC Technical Manual 05538C-23P/2 which covers complete maintenance and repair for the M16A2. Do a Google search on that TM number and you'll turn up reprints. Excellent reference. I used the earlier version for the M16A1 when I was in in the early 70s and repairing M16s. Headspace is the distance from the point of contact of the cartridge case shoulder with the chamber to the boltface. In layman's terms headspace defines the fit of the cartridge in the chamber with the bolt closed. Too little headspace and the bolt won't close, too much headspace and the cartridge will be too loose in the chamber. If the cartridge is too loose in the chamber: The firing pin will push the cartridge forward as opposed to simply impacting the primer; The case will overly expand to fit the chamber, usually lengthening beyond what was designed or intended and causing case heads to separate from the case body. Case head separation may or may not be accompanied with a release of gas pressure that has the potential for physical injury and for damage to the weapon. Head separations have caused magazines to blow out of the weapon, gas venting causing burns, and cracked or distorted upper receivers. Headspace is checked by using Go and NoGo gages inserted in the chamber and closing the bolt. Usually this is done with a stripped bolt (without extractor) but in the hands of an experienced 'smith the gage can be clipped under the extractor hook and guided into the chamber. The bolt shall not close and lock on a NoGo, and shall close and lock on a Go. You might also visit the BIY forum. HTH, Noah |
| Head space is usually adjusted by the barrel maker when the barrel extension (the part that mates with the upper receiver) is attached to the barrel. The only way to adjust it is to keep swapping bolt/carrier assemblies until you find a right one. The only other way to do it is to properly install and adjust the barrels extension. Most barrels come from the factory properly headspaced, but it does need to be verified with a "Go" and "No-Go" gauge before the weapon is safely fired. Sure, chances are good that the barrel was properly headspaced by the manufacturer, but who wants to risk a 51,000 c.u.p. explosion just inches from your face just to save a few bucks? Be safe, have fun! Also, anybody that is going to assemble their own AR's needs to invest in the AGI Armorer's Video "Building the AR15" available on Equipment Exchange or Ebay. |
AR Sponsor