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Posted: 11/30/2004 5:58:19 PM EDT
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Under the concept of "modular system", one lower with multiple uppers, life has been good with a Double Star lower w/NM trigger, and two uppers. A 16" carbine, and a standard upper with 24" barrel. The fit between the lower and both uppers is solid. Now the "grinch". I've been wanting a National Match upper to round things out. Have been saving my coins for about six months, and had a dealer with two RRA National Match uppers that more or less just sat there, and, you guessed it, just prior to my being able to buy, both sold within a week of each other. At a recent gun show, money hot in my pocket, got involved in an "aisle sale" with a gent that was carrying a "National Match upper" that was proportedly "almost unfired", and about $200 less than what one of the NM RRA units would have cost. Well, when I got it home, I checked it out as throughly as I could, and it appeared unfired. Then, when I installed it on my Double Star lower I was shocked (pissed). It was as loose as all get out. I have a friend with a standard RRA lower, and there was the same slop fit. I may have to go the AccuWedge and O-ring route, but I want to open this up to other REASONABLE suggestions. One was to open up the front pivot pin hole to Colt's . 315 dia, but I have the other two uppers to consider. Some other questions I have with this upper are: (1) it has a FA production code on the carry handle just in front of the sight, on the right side. Who uses FA prod. code? (2)on the rear sight there are 110 clicks of travel from bottom to top. How can I tell if this is 1/4" or 1/2", or something else, in elevation adjustment? The rear sight peep holes are far smaller than the rears on the other two uppers I have. What might they be (in dia.)? There is "0-2" stamped on the base. (3) The barrel is stainless steel, 20" long. I put a cleaning rod in the bore, and with patches, made it a tight fit. Then placed a piece of masking tape on the rod at the muzzle end and made a mark with an ink pen. Slowly I pulled the rod out until the ink mark had rotated one revolution. It did this in almost exactly 8". So, I assume the bore to have a 1/8 twist rate. Was expecting 1/9, as in my upper units. Typical NM twist? The front sight post is tapered, not square as on my other uppers. The handguards ride on free float tube, which I belive is standard on NM uppers. Oh, before I close, the rear sight "skews" to the left, much more than on my other uppers. Is this typical for a NM unit? Got a suggestion to fix this, by having a smith drill a corresponding hole on the right side for a spring and detent, to balance the one on the left thats causing the "skew". Is this a legitimate fix for this problem? Thanx for any helpful info that is provided. |
Use the Accuwedge if the slop bothers you...it really doesn't make much of a difference when you are in a tight position with a good sling. if you have 110 clicks of elevation it'd be safe to bet that you have 1/4 minute sights. Bench the rifle at 100yds. Fire five shots. come up 16 clicks and fire five more shots. Does the group move 4" (1/4 minute sights) or 8" (1/2 minute sights)? Rear Apertures are traditionally smaller for Nat'l Match uppers. Anywhere between .030 to .062" Front sights are tapered too...The thicker side should face the rear- FA does make NM service rifle uppers. 1 in 8 twist is optimal for NM uppers because we are using 69, 75, and 80 gr bullets. The rear sight skew is normal, but again, if it bothers you...send the upper to John Holliger at White Oak Precision and he will add posts to the rear sight. You might want to check out the Competition and Accurate AR forum |
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