Zeroing a KAC 200-600M BUIS

[pmclaine]

I'll be firing my new LMT CQB for the first time tomorrow. My scope has not come in but I want to zero the BUIS it will wear.

I have a set of the NSN numbered 200-600 KAC BUIS. I bought the rear used and I do not have directions for setting a zero.

I will be bringing LC 55 grn, Win 55 grn (NATO headstamp), Federal 55 grn, and some Nosler Match 77 grn. I intend to use just one of the manufacturers to complete my zero. The rest of the ammo is to release the pent up urges I have had to fire this rifle.

The CQB has a 16 inch 1/7 barrel. I think the Nosler will be the best ammo for the barrel twist but as 55 grn will someday once agin be the most economical plinking ammo (hopefully) I want to zero for that flavor. Is 55 grn a poor choice for accuracy in that twist barrel?

I plan on starting at 25 yards to get on paper. I would like to have a 100 yard zero for the rifle. The rear sight starting elevation is 200. There is also a Z (zero) mark up around 300.

I'm assuming I shoot my 25 yard zero on the Z setting and adjust elevation at the front sight post? Is there an initial setting for the front sight post? Its not like the M16 sight I remember where you start from "flush". The front sight post adjustment ring looks to be alway proud of its base.

Once zeroed on the Z setting at 25 yards whats my best setting to use at 100?

Thank you for any help you can offer.

 

[Redmanss]

As I've read from KAC on other forums... Zero at 25 *METERS* with the sight set on the "Z" (300m) index. That should put you pretty close but as always confirm at distance to ensure you're hitting the standard velocities with your setup. As for the initial setting with the FSP, bore sight that sucker the same way you would a scope. Pull the BCG, sight through the barrel lining it up on an object downrange and adjust the FSP and windage as necessary. Acquire your initial zero and confirm at distance. Keep in mind these sights are designed for M855 62gr ammunition but will work well enough inside 300m for anything you will be shooting through it anyhow.

100yd zeros aren't recommended for rifles such as yours running iron sights. There is too much dispersion at varying ranges when you try that, and a Battlesight Zero (BZO) is just that, allowing you to engage everything within small arms fire distance without significant holds being necessary. I prefer iron sights with a 300yd zero and a 36yd close range zeroing for iron sights, but everyone has their own purposes and applications. Chronny your ammunition you're wanting to shoot and start playing with it on a ballistics program. Figure out what is going to work best for you.

As for your choice in ammunition, 55gr will shoot just fine from a 1/7 twist provided it's quality enough projectiles and don't have overly thin jackets. I wouldn't recommend going any lighter though.

 

[pmclaine]

I dont know why they call these back up sights. They shot great and would work as a primary. I wish my back ordered off sets would come in.

I used a 25 yard range and was probably one front sight post click high. Ill try them at 300 next week and Ill be "right there" with my hits.

Thanks for the detailed reply post.

 

[mewillis]

PM me your email I have a PDF of the instructions

 

[pmclaine]

PM me your email I have a PDF of the instructions

PM sent.

Thank you.

 

[Alaska]

I would think the KAC rear sight ranges were calibrated for M855 ammo using the heavier 62gr bullet than the 55gr of course you will have to adjust the evelation knob accordingly for 55gr.
Great info already given !