AR-15 sight help

[SudSlinger]

I recently purchased a new CMMG m4 with a 16in barrel. I used a laser bore sight to initially sight in the rifle. The rear sight ( a flip up BUIS to my Eotech)
had to be adjusted all the way to the left in order to match up with the laser dot. At the range i started my sighting in from this point. The rear sight is still all the way to the left and the rifle hits exactly where i want it to when using the iron sights. Is there anything to worry about? It just seems that it was a rather extreme adjustment for the sight to have to be all the way to one
side. Any help is greatly appreciated.
I'm new to posting but have been reading the site for awhile. I look for to becoming a more active member.

Blake

 

[Shawn Dodson]

It appears the barrel nut was torqued while the upper receiver was secured in a receiver block. Your experience is a common one.

A receiver block allows the barrel to turn as torque is applied, which causes the front sight to be off-center. To compensate the shooter has to crank the rear sight all the way to the left.

If the condition doesn't bother you then there technically is no problem. If it does bother you (and I reckon it eventually will because you can't acquire a comfortable cheek weld with the rear sight all the way in the left stops or near it) then you should see about having the barrel retorqued using a barrel block.

Cheers!

 

[Mainsail]

My upper is a CMMG and with the rear sight flipped up, it and the front sight line up nicely with the EOTech. The rear sight is centered.