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Old January 13, 2020, 01:46 PM   #17
BobCat45
Senior Member
 
Join Date: May 18, 2004
Location: East Bernard, TX
Posts: 344
You can shoot at those yardages but you can also make an inverted lollipop target, with an aiming point at the bottom of a tall piece of paper, and a vertical line up from the center of it. When you hang it, use a plumb bob to get the line vertical.

Shoot at the aiming point to zero, then add some elevation to the rear sight and shoot another group, and so on. If the groups stay centered on the vertical line it is likely that you have no real problem at all.

On an AR-15, the 'standard' come-ups are 2, 3, and 11 minutes up from 100 yard zero, for 200, 300, and 600 yards - just to get on paper reliably. So if your vertical line is a foot (12 inches / 12 minutes at 100 yards) you can learn quite a bit about potential elevation-induced windage changes.

If you find that you'd really like / need to turn the front sight post as close as you can to vertical, there is an option that will work but I hesitate to bring up because it sounds so crude.

Background: The Bushmaster DCM model sold through the CMP in the middle 2000s was a good, but not superb, rifle for NRA/CMP Service Rifle class. The front sight base was held on with Locktite 290, Sleeve Retainer - no cross pins or set screws at all. Claim was to not to stress the barrel, but I think it was just cheaper than flats and setscrews per White Oak etc.

Edit - I was wrong about 290, the current name is Permatex PX64000 Sleeve Retainer. I do not know the Loctite number, it is marketed under the Permatex brand name at autoparts stores. Label says "High Temperature Sleeve Retainer" and has a picture of cylinder liners being pressed into a block.

This sounds really weak and crappy but that stuff takes being heated with a propane torch, and the sight base being vigorously beaten with a stout plastic mallet, to remove it. I know this sounds full-of-excrement but it is true and verifiable.

You can drive out the cross pins, free up the sight base, turn it to get it where you want it, scribe a line, remove the sight base, clean the barrel and base with acetone, and re-assemble with the 290 to hold it.

I understand, SHTF rifle and all, but it will not come loose without significant heat and force. You will find this out if you do not get it where you want it the first time.

Best of luck and enjoy your problem and its solution. Life is boring if it all works right the first time (my opinion only).
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Last edited by BobCat45; January 13, 2020 at 02:04 PM.
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