View Full Version : Crooked front sight on AR?
My upper has a fixed front sight built into the gas block. I have recently noticed that the front sight is slightly canted to the left, forcing my rear sight post to be almost maxed. Any suggestions as to how to fix this?
If it is the whole front sight assembly, take it to an AR armorer and have them fix it. May have to loosen and re-tighten the barrel.
First suggestion: contact the manufacturer and see what they can do for you.
Do you have a regular pinned front sight block? Or is it some kind of set screw or clamp-on doodad with a rail on top?
It's a pinned front sight.
If the front sight was drilled and pinned at an offset which is out of alignment of the gas port and indexing pin, it is not a simple fix, but can be done. Have you contacted the manufacturer about this?
I have not. I think I'll just bring it back to my local shop. One of the guys there has taken great care of me so I'm sure that's something he can fix.
Thanks everyone for the help!
An Undocumented Worker
03-22-12, 23:20
Is it fixed?
The problem? Or the sight?
Would think barrel indexing pin would keep barrel aligned so fix would have to be at front sight tower.
If carbine is near new, hope your dealer will get it fixed/replaced.
Curious how it can be fixed; new holes for pins in barrel would run into old ones, so fit might be loose, and new holes in tower would look funky.
Hope it all works out and would like to know how it goes.
Mark
polymorpheous
03-23-12, 09:30
The barrel indexing pin interfaces a notch in the upper receiver.
Watch out that the gun store doesn't take care of you by using a Dremel on the upper's indexing notch allowing the barrel to rotate slightly in the receiver.
Most gun shops don't have the fixture or milling machine to pin a FSB.
machinegunbob
03-23-12, 09:34
Get a Brownells front sight block and drive out the old pins and install new pins.Should correct your problem.
polymorpheous
03-23-12, 09:37
Get a Brownells front sight block and drive out the old pins and install new pins.Should correct your problem.
Why do you think that will solve the problem?
machinegunbob
03-23-12, 10:13
A lot of times the front sight taper pins are driven not using the proper sight block.This keeps your sight from rolling when installing taper pins.I have been a gunsmith for 30 yrs.and found that in most cases that's the cause.
polymorpheous
03-23-12, 12:16
A lot of times the front sight taper pins are driven not using the proper sight block.This keeps your sight from rolling when installing taper pins.I have been a gunsmith for 30 yrs.and found that in most cases that's the cause.
So if he doesn't own this FSB block, what's to stop his FSB from rolling when he reinstalls new pins then?
I used the flat end of my bench mounted vise.
How did I keep my FSB's from rolling when I used the original pins to reinstall my FSB after mounting a freefloated hand guard?
Instead of sending it to the local "gunsmith" you should contact the company who made it.I know everyone wants instant gratification in this day and age.
But, they may have a production issue and they can't fix it, if they aren't aware of it.
patrick sweeney
03-23-12, 12:34
A problem not seen much any more. Back in "the day" when everyone was frantically trying to crank out barrels in the (pick one, any one) impending assault weapons ban, we saw more crooked sights. Today, very few.
OK, easy one first: if it is new, take it back. The dealer, or the manufacturer, should make it right.
If it is not, things get trickier.
The barrel index pin sets the barrels location, there is no "tighten it some more" option on the AR. That's out.
The sight tower might re-straighten if you drive the pins out and re-seat them. And it might not. Can you live with it as-is? Does the barrel group well?
When this situation happened in the past, I used a special fixture that held the front sight in place, with the pins out. The process was simple; fixture on, pins out, rear sight centered. Shoot in the 100 yard backstop, and adjust the fixture screws, tipping the sight up until the bullets hit to point of aim.
Once zeroed, the sight tower and barrel pin location were drilled the next size up, and straight solid pins installed, with lots of loctite.
I know, I know, straight pins "don't belong" and loctite is evil and verboten. But in the late 1980s, there were not over-sized taper pins (still aren't, as far as I know) and that was the only way to solve the problem.
If your gunsmith doesn't have a fixture like this, then he can't do as I did. If the manufacturer can't/won't solve the problem, then you live with it.
I recently purchased a bbl from a well known maker and the front sight tower is slightly canted to the left. I decided to shoot it and see what happend. I had to move the rear sight a few clicks left of center to get zeroed at 25 meters and it shoots just fine. No malfs in over 100 rounds so far.
I wasn't aware of the un-install-re-install trick so I may give that a try sometime just to see if it works but for now it's shootin just fine as is.
OP, Let us know how it turns out for you.
B.
"Uninstall, re-install" is asinine. Unless the holes or pins have been damaged, the fsb will end up in the same place every time.
Hello Aiannare,
Specialized Armament has Oversize Tapered FSB Pins http://www.specializedarmament.com/products/FRONT_SIGHT_TAPER_PIN_OVERSIZE-228-4.html
SA is also more than capable of fixing your gun, but when it comes to AR's - they usually only work on COLT, FN, Hydramatic and H&R http://www.specializedarmament.com/content/skins/flat/popup_issue_98.html
Except I've seen it work when the FSB was slightly off center...won't do anything if it's off more than that. Patrick Sweeny's post covers all the scenarios I know.
polymorpheous
03-24-12, 21:30
"Uninstall, re-install" is asinine. Unless the holes or pins have been damaged, the fsb will end up in the same place every time.
Exactly.
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