Re-barreling and Installing a Float Tube on a 5.56mm Service Rifle - AR-15, etc. - Page 1
One of the problems a 5.56mm Service Rifle Shooter faces is flexing of the barrel due to sling tension. This flexing can be countered in two ways; a very heavy barrel can be used, or, the sling can be secured to something other than the barrel. If the rifle is NOT subject to the Service Rifle Rules, a cheap aluminum tube can be used to replace the handguard assembly, with a sling swivel suitably attached.
About 5 years ago (1997?) Armalite offered VERY heavy SS barrels, but these are no longer available. When they were available, I assembled some Service Rifles for use in CMP and NRA Service Matches. I think Wilson made these barrels, but that is just a guess. The markings LOOKED the same as some barrels I know were of Wilson origin.
My brother put over 5000 rounds through his rifle, including shooting some "possibles" at 100, 200 and 300 yards at local matches and at Camp Perry. The throat (or leade) increased about 30 thousandths during this shooting, and he felt the time had come to replace the barrel.
Although the heavy barrel had served him well, a replacement was not available, and so he elected to go with a "floating handguard assembly". He selected a SS unit made by W. H. Merchant and sold by Brownells' @$134 (retail). I have installed many Service Rifle Rule tubes like this, (Armalite, DPMS, generic) but this one is the best I have seen. A very clean design, strong, and well built.
First, sight was removed from the old barrel.
The rear sight is secured with tapered pins, these are driven out with a pin punch. Make sure to drive from the SMALL end!!
The sight is then driven off the barrel, along with the forward handguard retainer, using a brass drift. See the hole through the barrel, formerly occupied by a tapered pin.
The upper is then placed in a holder/clamp in order to hold it in the vise. These holders fit standard uppers as well as "flat top"s. This holder is sold by Brownells and can be found at some gun shows. Should cost about $35.
With the upper held in the vise, the old barrel is removed. The wrench in my hand has been modified to fit the overly large barrel.