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Posted: 5/22/2005 1:26:02 PM EDT
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Had a barrel begging for a place in the bunker and decided to start building it at 8:30 pm so the photos are a little nasty as all of mine are. The barrel is a 24" Saber barrel, 1/9 twist and stainless with a very nice finish and target crown, barrel demension is .750 forward of the gass block and .958 under the free float tube, with a .223 chamber. I started off with a Flat top upper from Tonys uppers, maker unknown. I am not into name brands so I take what works.  After a dry run and checking that all is Kosher with fit and finish I lube the barrel extension with Brownells action lube and slide the Stainless barrel on the upper and lube up the barrel nut and upper receiver threads with more Action Lube until it threads easy and fits with no resistance.  I tightened down the barrel nut to 50 foot pounds and this time I did do the 3 times tighty and loosey since the barrel nut was very stiff and it smoothed out fine. Then I mated the gas block and gas tube, on free float tubes like this you can add the gas tube prior to placing it on the barrel and then slide the entire assembly on. Making sure the barrel nut holes are aligned properly to provide unrestricted access to the uppers gas tube portal, then I secured the gas block buy the two Allen head screws so to secure it well. These gas blocks are alloy and east to strip the threads so lets not be to hasty on excessive force, just tighten them down enough until you feel resistance. Now you spin on the free float tube and adjust the jam nut to secure the FF tube, did I mention that the tube comes already threaded for a bipod?   Now it rains!  Back to the shop and to finish the job. Finished it and test fired the upper, it shot a group the size of a dime at 80 feet for a good first firing.   |
Not every time  The threads on a FF tube barrel nut will squall like a hit cat if you do not do this with lube. 
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