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1/25/2018 7:38:29 AM
Posted: 2/28/2006 10:28:26 AM EST
When hammering a canted FSB back in place am I rotating the FSB around the barrel or rotating the barrel in the reciever?

Link Posted: 2/28/2006 10:30:35 AM EST
If it came that way from Bushmaster, send it back.
Link Posted: 2/28/2006 10:39:32 AM EST
Only the barrel did. They suggested I loosen the barrel nut and reposition it. They said it will propably have a small amout of play that will make a difference.
Link Posted: 2/28/2006 11:52:15 AM EST
Make sure that you know which is canted -- the front sight base or the barrel itself. There's a 99% chance that the front sight is fine and that the problem is the barrel is canted in the upper receiver. If so, you'll need to remove the barrel nut and reposition the index pin in the upper receiver's slot.
Link Posted: 2/28/2006 5:00:53 PM EST
You will only have about a 1/64" if that, amount of movement in the upper receiver slot where the index pin resides, after you loosen the barrel nut. But that does translate into more movement at the tip of the front sight base due to the height away from the axis. Hope that makes any sense. If your front sight is more than an 1/8"-1/4" out of spec, you probably won't have any luck trying this option. I would sent the upper back to the factory and have them make it right.
Link Posted: 2/28/2006 5:07:59 PM EST
Also, I would not recommend hammering on the front sight base. It would be much wiser to insert a breaker bar through the front sight post and try to twist the barrel while the upper is being held in an armorer's action block in a vise. The proper way to do it is to loosen the barrel nut, twist the front sight base the direction it needs to go with a pry bar and have someone else hold the front sight base in that position while you tighten up the barrel nut again. Typically the front sight base will twist in the direction that the barrel nut is being tightened in, usually canting the front sight to the left when looking through the sights from rear to front. You want someone to be putting slight pressure in the oppisite direction while you tighten down the barrel nut, if that is the direction your front sight base is canted.
Link Posted: 2/28/2006 6:46:18 PM EST
[Last Edit: 2/28/2006 6:46:58 PM EST by Dano523]
Link Posted: 3/1/2006 2:59:51 AM EST
I am doubting it has to do with the barrell nut simply because it is twisted to the right (looking down the barrel). I did not notice it until I mounted my eotech and could see it was canted in the window. Then when I went out to the range to zero the irons, the rear aperature had to be pushed almost all the way to the right. I am still considering removing the FSB and installing a flip up front sight which will give me the ability to adjust it. Fron inside the upper reciever, the barrell extension apprears to be sitting perfectly. Other than the sights being canted, it feeds ammo very well and once the eotech was sighted in, it was quite accurate and consistant. I found that with the GG&G BUIS at the rear, the front sight post is a bit too short, so I'll need a longer one.
Link Posted: 3/2/2006 2:31:06 AM EST
A couple of taps with a dead blow got it right back into alignment.

Link Posted: 3/2/2006 7:38:45 AM EST
as no one stated clearly :

you are rotating barrel in receiver.

the FSB provides a nice leverage point.
Link Posted: 3/2/2006 8:21:24 AM EST
Yes, I really did not think it was going to month considering I was just holding the rifle as instructed but a couple of well placed shots did the job. I am not a fan of fixing things with hammers and duct tape but it appears to have been what the doctor ordered.
Link Posted: 3/2/2006 9:05:19 AM EST
[Last Edit: 3/2/2006 9:56:04 AM EST by Dano523]
Link Posted: 3/2/2006 9:16:30 PM EST
tag for ref
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