Posted: 1/18/2010 4:38:39 PM EDT
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I have an inexpensive kit gun AR15A2, and I want to use it to get started in Highpower, then upgrade to a better rifle when the budget allows. It needs a fair amount of left windage put on the rear sight to zero for windage.
I see that most rifles built for match use use a front sight base that is adjustable via setscrews. On the ones I've seen the setscrews bear against flats milled in the barrel. I've seen information regarding drilling out the pin holes in the "standard" front sight base, then tapping them for setscrews. This looks dead easy and is well within my capabilities to on my drill press. However what can I do regarding the lack of flats on the barrel to match up with the setscrews? Will the setscrews work by bearing against the pin holes? Has anyone done this - used a setscrew front sight base on a pinned barrel - successfully? If so, how? Thanks. |
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I've done quite a few.
Go here I plugged the Bbl pinholes with welding rod then Loc-tite them in with the hi temp. I, then modded the base this way and used a dremel tool with a cutter for the screws to butt up against. 'Borg ETA, you also might look around on that web site, more info on modding the sights. |
| I did it with dremel, get a few of the rotary file bits it will take a few to complete the job. Unless you can find ones that are carbide tipped or a better grade of material than the ones I bought over the counter. I also sweated my pins in using plumbing solder(no silver, just lead and tin) instead of an adhesive. |
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I don't think it's that important, after all it's just a flat spot for the screw to butt up against, and screws are adjustable.
For the length of the cut,, just a flat spot. You also don't need to go deep, just enough for the screw to clear the Bbl on the top of the screw. Once you look at it, you should be able to tell what you need to clear, just to the top of the pin hole. 'Borg |
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Well, I slept on this whole issue, and I've decided to not fool around with the conversion. My reasons are:
1. I hope within a year to buy a "real" CMP-legal match upper that will have all the bells and whistles anyway, and upgrade my trigger group to a 2-stage. 2. If I change the FSB to setscrews, unless I buy a free-float tube and handguard at the same time, my sling swivel will still be hanging off the bottom of the FSB and I'm afraid a tight sling may rotate the FSB around the barrel. 3. If I'm going to replace the upper anyway, why spend the money to free-float what I've already got (when it probably shoots better than I can shoot it anyway). 4. I can still replace the trigger whenever I can raise the money, and it will probably improve the shootability of the rifle as it is today anyway, and still use the lower on my upcoming DCM uper when I get it. 5. If I replace the barrel, FSB, rear sight, handguard and free float tube, etc., I've probably spent more money than it would cost to just buy the complete DCM upper. I think I'll just live with it as-is, shoot it in as many matches as I can, and learn the ropes. Then next year, with the new upper I hope to have, I can get serious. |