Question, I looked through the Bushmaster Armorers manual and the USMC one and can’t find the answer. I was wondering if someone can post or email me verbatum from a source that states how much is to much for windage adjustment to zero.
I won’t get into names yet(they’re going back Monday) When I got these two uppers, I zeroed them at 50 and noticed then the excess windage to accomplish this. I’ve been pretty busy and put them in the safe and took them out ther other day to look at them since they will be replacing olders ones soon. and started thinking about the issue again, I took them to a certified Armorer and he pointed out the obvious-the front sights on both are canted to the right from the users end.
Any way, one is set up with a carry handle and the other with an Aimpoint and a Larue back up. I didn’t count the clicks on the Larue, but it’s further than the A3 one. 20 Clicks right to zero at 50. It’s a huge distraction with the Aimpoint to go from that to the irons, head shift and obvious head position on the A3.
Let me qualify some things, it’s not an eye dominance issue, ammunition or marksmanship. No AR based gun I have/had has taken more than 6 clicks to zero, one MZ is zero.
I appreciate any help with the data, I may need it to discuss the fine points later.
I won’t sling mud unless they aren’t replaced or fixed properly, which is another question.
I would only point the name to alert others to spend their money elswhere.
Obviously, from your perspective, it’s too much. (I’m not disagreeing.)
Are you referring to a TDP-like acceptance criterion?
I do note that in the Army’s M16/M4 Tech Manual TM 9-1005-319-23&P, page 156, we have:
The rear sight aperture will be approximately in the center of the rear sight base if the rifle barrel assembly is properly aligned in the upper receiver assembly. … If rifle barrel assembly … is not properly aligned in the upper receiver assembly…, excessive windage will be present…
“Excessive windage,” however, is not defined. One definition may be more adjustment than the sight can accomodate.
My rule of thumb generalization scientific wilda** guesstimate is that if I can notice at first glance that the rear aperature is definitely to one side or the other, it’s too much windage adjustment. In such cases, I’d check to see if the front sight/tower was clocked too far (which it probably is for whatever reason), and get they remedied ASAP.
But then I’m nobody, so take it for what it’s worth!
Many times you can put the upper receiver in a block (in the vise) and twist the barrel within the upper receiver the way you need it to go. If it’s hitting to far to the right, twist the barrel to the right.
I usually just loosen the barrel and retorque it. This problem many times comes from people using barrel blocks (instead of upper blocks) to hold the barrel as they torque down the barrel nut to the receiver. I can also come from overtightened used a vice receiver block.
If it hits too far to the left, they probably overtightened using barrel vise blocks.
Sometimes a new barrel extension indexing pin will fix it, sometimes it requires a new upper receiver.
I would like someday to make a jig that holds both the upper receiver and the barrel perfectly still while the barrel nut is torqued.