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1/25/2018 7:38:29 AM
Posted: 8/27/2003 11:13:55 AM EST
Ok guys another day at the range. I have posted before about the issue I am having with the front sight. I replaced the carry handle on my flattop with a dpms carry handle from a gun show. It matches up with the rail system much better than the cheaper than dirt one.

However instead of 18 inches off I am now only 3-6 inches off. I can adjust the windage and get dead center. However I have to adjust the windage all the way to the left side to get it dead center. I have taken the front sight off and tried to adjust that but every time I tap the pins back in it moves the front sight back to the same position so I am thinking that is not the fix.

Any Ideas?
sorry for the long post.
I am using standard South African 223 ammo at 25 yards
using sandbags to rest the rifle on. It is a Heavy barrel and I am using a free floating front handguard from Bushmaster, the lower is a RRA standard parts kits from a local gunshow

Link Posted: 8/27/2003 11:38:11 AM EST
After you drive the front sight pins back into the barrel is the front sight positioned at Top Dead Center relative to the flattop receiver? If not, then the barrel indexing is messed up. You can switch to a system using hex-headed locking screws instead of taper pins. This will allow you to rotate the front sight block to TDC, and salvage the barrel. If the front sight is plum, you could have a problem with the picatinny rail on your flattop and the way the carry handles are fitting it. If there are any burrs or bumbs on the rail this could shift the rear sight.
Link Posted: 8/27/2003 1:10:27 PM EST
I felt the rail and it does have a slight bumb was wondering about it I will try filing it flat. As far as Top Dead Center on the front sight how would I check that I assumed by the sight pins not being able to be tapped in until I had the sight fairly centered I assumed that it was centered. Perhaps the assumption has made an a$$ of me. Thanks
Link Posted: 8/27/2003 2:07:10 PM EST
Here is the [url=http://www.ar15.com/forums/topic.html?b=3&f=4&t=165221&w=searchPop]Thread[/url] for others, including my self, with the same problems. I have a J&T flattop upper with a M-4 profile barrel with an ARMS #40 BUIS. To sight the thing in, the #40 had to be cranked all the way to the left (front sight tower leaning left). So after purchasing the appropriate tools; barrel nut wrench, action vise block, etc... I had to disassemble the upper. Once the barrel nut was loose, the barrel would rotate counter-clockwise (as looking at the muzzle) a good 1/8". I used the peening meathod to fill the space so the alignment pin wouldn't rotate back when the nut was tightened back. Well, I'm going to have to file a little off of the one side to make it perfect. Right now the #40 is about half way between center and full left. I'd like it a little better... If it was new, I would send it back to J&T, but I got it off of the EE second hand, but almost new. Good luck!
Link Posted: 8/27/2003 6:09:28 PM EST
To check for TDC on the front sight try this: Place the rifle on a shooting rest of some sort that is stable. Using a level, insure that the flattop of the receiver is horizontal front to back and side to side. Once this is accomplished, place a small level vertically directly in front of the front sight. Set the bottom edge of level at the "top" of barrel as closely as possible, align the rest of the level so that the edge runs directly towards the front sight post. The bubble on the level should be centered. If it isn't the front sight block is rotated relative to the receiver.
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