Bushmaster front sight

[tinroad37e]

Well, I took my new Bushmaster 6.8 to the range today to check function and sight it in. It shot high about 8 inches, so I attempted to adjust the front sight. I tried using a nail to turn the sight post, but the thing wouldn't budge. The range owner was nice enough to loan me his front sight tool, but the tool was too wide and wouldn't fit between the guards on the front sight post. I've been in the U.S. Army for 14 years (6 years to go and I can't wait)and we always adjust our M16/M4with a nail at the range with no problems. Are the Bushmaster front sight posts usually this tight? Surely they wouldn't use locktite. I have no idea why his front sight tool wouldn't work; I thought they were all standard.

 

[Onmilo]

Bushmaster does not use any lubricant in the front sight hole when they assemble.
Consequently many front sights are seized.
Drip some good penetrating oil such as Kroil into the post hole and let it soak for a couple hours.
The front sight will adjust much easier.

I use a 3/32" pin punch to remove the front sight post the first time and clearance the sight ears with a Swiss file to allow a front sight adjustment tool to be used thereafter.

I don't know what upper receiver you selected for your rifle but the 6.8 barrels usually require a taller front sight tower or the taller 'carbine' front sight post to regulate when paired with flat top uppers.

Consider this when you get your front sight post loose should you still not be able to regulate and zero the rifle.HTH

 

[tinroad37e]

It's a Bushmaster lower and upper.

 

[Onmilo]

I already figured the upper and lower were both Bushmaster.

What I meant was whether the upper was a fixed carry handle A2 version or a flat top A4 version, I apologize for not clarifying.

Did you get the post moving yet?

Bushmaster produces some excellent barrels and the front sight towers aren't half bad either but those guys don't final finish the sight towers.
The owners need to get in there and clearance the sight tower to mil spec dimension standards if they want to use an adjustment wrench for sight adjustments.
I use a lot of Bushmaster barrels on custom builds and clearancing the sight tower is a standard procedure for me. HTH

 

[tinroad37e]

I gave it some penetrating oil last night and have tried it with a nail, but it still won't budge. I ordered a front sight post tool off Bushmaster's website. It should be here in a week. Hopefully it will work. It is the flat top version with the removable carrying handle.

 

[Onmilo]

Will the detent not budge or will the detent depress and the sight post not turn?
Just for kicks, look at the front of the front sight post and make sure a National Match type front sight post wasn't used on your rifle.
These front sight posts have and allen head screw that turns in and locks the front sight adjustment so that nobody can fiddle with the sight settings once adjusted.
If that screw is there you will need to back it off before the detent will depress or the front sight will turn.
If that little part isn't present and,,,,,,,,
Since you applied oil and let us figure everything is still froze up, so, try this,,,
Use a 1/16" or a 3/32" PIN PUNCH, skip the nail, it is probably too large in diameter to fully depress the detent,,,use the pin punch and a light hammer to tap on the detent until it moves freely, up and down on the spring.

Once the detent is free and moving and you can fully depress it, you should be able to move the front sight post with fairly light pressure.

If the front sight post still won't move with the detent fully depressed try this,
depress the detent with the pin punch then angle the punch so it is against the side wall of the detent notch on the front sight post,,,use the light hammer to gently tap the punch against the post notch, this should free the post enough to allow it to turn freely.

I don't believe the front sight tool offered by Bushmaster will work any better than any other until you clearance the sides of the sight ears but I may be wrong on this.

Good luck, sounds like you got the front sight from hades on your hands.

 

[tinroad37e]

The plunger will depress, but the sight post will not rotate much at all. I did use a small punch, and with a hammer, I rotated the front sight post 1/4" clockwise to lower the post, but it won't move any easier. I even tried to turn it counter clockwise, but it won't turn that direction either. I was thinking about using needle nose pliers, but I don't want to break off the sight post. If the tool from Bushmaster won't fit, or work, I'll call Bushmaster and see what they're willing to do. It may possibly be crossthreaded.

 

[jrfoxx]

huh.Wierd. I just pushed in the pin on mine with a straightend paperclip, then used some needle nose pliers to grip the post and turn. Mine turned real easy. Guess I got lucky.