little help please

[StudioDison]

CAn someone explain to me the functions of this sight. I.e. the two sight holes.
the larger one has 0-2 stamped on it.
I just got it for my current build.
Thank you

[bobfried]

The larger one is for low light usage. Flip it back and forth to select the appropriate peep.

[StudioDison]

OK thanx. since there is no elevation adjustment, what will it be rated at?
300 yards?
it will be used on a 6.8 16" upper

[fusionstar]

hmm.. no elevation?

Never seen an a1 upper in 6.8

In any case, the 0-2 is for close range, low light, and moving targets.

Your front sight post can also be adjusted for elevation.

[dieselpower]

I tend to stay away from A1 type BUIS when dealing outside of Mil-spec. The height of the FSB post and BUIS need to be dialed in, and frankly the math is more about actually shooting at range then a quick, 30meter battle zero = 330meter zero.

Now if you are looking for emergency use of the BUIS, then first measure the front post from center bore, Full range of adjustment then the center of the unlabeled peep BUIS to bore. Write those down, start with both measurements being as close to equal as you can get. You now have a straight line X inches above bore. Find the trajectory for the 6.8 you are using. You should be able to figure out where the best FSB height = the best ranges you are going to shoot at. Then the larger peep is just used for close shots while the smaller will be for the longer shots.

Good luck.