Rear Aperture off Centre

M

macdonda

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I bought a Diamondback DB15 USB in the ‘pre-ban sale’ and I like it, reliable and accurate enough for me... I wanted to have one with iron sights... anyway I bought a junk carry handle/sight straight from the Orient that had the rear aperture way to the left to centre on target at 50 yards. It broke so I replaced with a reasonably good one but I notice the same thing... there’s a bit of windage adjustment room remaining but only about 1/16”. It looks like my front sight is off centre by about 1/8”. It’s more of a nuisance than anything but wondering what my options are? I don’t have tools needed to remove FFS or loosen barrel nut, willing to pick them up if it’s a relatively easy fix.

I’ll appreciate any ideas... Thanks!
 
Not familiar with the DB15... Is the front sight part of the gas block? And if so, is the gas block pinned, clamped or screwed in place? I don't believe that there is any significant degree of adjustment on the barrel.
 
Garaldtao said:
Not familiar with the DB15... Is the front sight part of the gas block? And if so, is the gas block pinned, clamped or screwed in place? I don't believe that there is any significant degree of adjustment on the barrel.
Click to expand...

Unfortunately it’s pinned in, I read a couple spots to remove, slightly file down pins on one side & reinstall but not always with success
 
I read also about shimming the key slot into which the index pin goes but don’t think I’m at a point where I want to take the barrel off, really want to keep the carry handle sight - I can live with it as-is worst-case but not sure if there might be something simple else I could try
 
There are a couple of ways to go about curing this problem, both involve removing the flash hider, if there is one, then driving out the cross pins then removing the front sight housing from the barrel. Once that is accomplished, the easiest fix is to tap the 4 holes you now have in the front sight housing 6/32 and put in some set screws. Reassemble everything and centre the rear sight in it's housing. Now zero your windage while shooting by moving the front tight until your groups are centred. This will involve tightening and loosening the screws repeatedly until you have your zero established. Once you have a good zero, mark the front sights place on the barrel. Go home and remove everything and put green hydraulic locktite on both the barrel and front sight housing. replace everything on the barrel and put the front sight where you have marked it then tighten down those screws. They are there to hold the sight in place until the locktite cures.

If your sling swivel is not attached to the front sight housing but on a free float tube of some sort, there is no need to green locktite the housing to the barrel.

The second method is, once you have the front sight housing removed, drill and tap through the bayonet lug and the sling swivel housing to 8/32. Then carefully cut through the bottom of the front sight housing, you can do it with a hacksaw. You have now made a clamp on front sight housing. Decide which side you want the hex bolt head to be on and drill a clearance hole on that side. You will also need to drill out the sling swivel itself to take the 8/32 bolt.

It sounds harder than it is and it gives you a very solid front sight that can be adjusted for windage.

Scott
 
m39a2 said:
There are a couple of ways to go about curing this problem, both involve removing the flash hider, if there is one, then driving out the cross pins then removing the front sight housing from the barrel. Once that is accomplished, the easiest fix is to tap the 4 holes you now have in the front sight housing 6/32 and put in some set screws. Reassemble everything and centre the rear sight in it's housing. Now zero your windage while shooting by moving the front tight until your groups are centred. This will involve tightening and loosening the screws repeatedly until you have your zero established. Once you have a good zero, mark the front sights place on the barrel. Go home and remove everything and put green hydraulic locktite on both the barrel and front sight housing. replace everything on the barrel and put the front sight where you have marked it then tighten down those screws. They are there to hold the sight in place until the locktite cures.

If your sling swivel is not attached to the front sight housing but on a free float tube of some sort, there is no need to green locktite the housing to the barrel.

The second method is, once you have the front sight housing removed, drill and tap through the bayonet lug and the sling swivel housing to 8/32. Then carefully cut through the bottom of the front sight housing, you can do it with a hacksaw. You have now made a clamp on front sight housing. Decide which side you want the hex bolt head to be on and drill a clearance hole on that side. You will also need to drill out the sling swivel itself to take the 8/32 bolt.

It sounds harder than it is and it gives you a very solid front sight that can be adjusted for windage.

Scott
Click to expand...

Cool, great ideas - thanks!
 
And... I couldn’t live with it lol simply bugged me too much. I loosened the barrel nut, then wrapped and kept a wrench on the front sight and held counter clockwise while I re-tightened the barrel nut to about 40 ft-lbs. Hit the range and aperture is almost fully centred (actually slightly to the right now)... I’m surprised how much play there is in the barrel fit.
 
If it bothers you that much, get a hammer and smack the front sight forging over the direction you want it.

Then go buy a new one when it breaks.
 
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