Official M4 Mil manual specifies setting the Matech to the 300 yard setting and use a target at 25 yards. The range I use only allows rifles at 50, 100 and 200 yards. What would be the best way and range to zero this new build. Its a Colt M4 LE6920 with a new pinned /welded 14.5 1/7 twist barrel, with F marked front sight. rear sight is your standard Matech.

Something like this might work for the irons. Scroll down for their different distance targets.

Edit: Even though it says for red dots, they should be usable with lining up for irons.

http://arma-dynamics.com/red-dot-zero-targets.html

It's calibrated for M855 only. How far off other stuff would be from it, I don't know.

There's a 300 mark on the sight, and a line mark next to the 300 mark. Wish I could remember which is which, but an M16A4 is to be zeroed on one of those, and the M4 on the other.

Magtech's instructions with the sight says which.

ETA: I need to read more carefully. Glad you got that answered. The sight and zeroing procedure is for meters though, isn't it?

As far as zeroing... you could plug in the mil's numbers with what you can find into a ballistic calculator (hornady or Federal for online free ones). Get 25m and 300m pretty much spot on together for the 62gr M855. See what it says at 50yd. and 100yd.

Can you not go prone and shoot a quick zero on the range??

The Matech manual says use the 300 meter mark to zero at 25 m.

Using my ballistic calculator. Iron sight height over bore should be 2.6" and M855 with a ballistic coefficient of .304 and a muzzle velocity of 2907fps.

At 50 yards you should be 1.9" high. Sight in your 300m mark 1.9" high at 50 yards.

As per my 3AM math.

OP:

Forget the Army crap in the manual/instruction sheet.  That stuff is "ballpark" only and to the credit, it even says in some of the manuals.  I own my own range and can shoot to 1000 meters.  I don't rely on Army parts spec instruction sheets.  They are rough estimates only.

In fact, just last Saturday I zeroed a new Matech rear sight myself.

Take the rifle and use your range distances to know what it is zeroed at.  If you are pretty much shooting there anyhow, that's where you want to KNOW the zero.  Decide what extreme range you want the rifle zeroed at.  For you that is going to be 200 if you shoot at that range.

Assuming you are starting with an un-zeroed rifle, start at 50.  Zero it dead on.

Walk it out to 200 and see where it hits.  Adjust if necessary or simply write down the POI and tape it to the stock if you can't remember it.  Shoot at least one ten-shot group to establish zero.

Back up to 100 and see where it prints.  Record that.

You are done.

Now you KNOW what the POI is at the various ranges and you don't have to pretend to know by relying on the blather of a sight manual/instruction sheet other than for rough zeroing.

Pretty much what he ^^ said.

Zero it at 50, got to 200, fine tune it, see that it hits about 2" high at 100, fold it down and forget about it.

Topic Moved

Thanks for all the info. It looks like for my application, I will set the sight on the 200 setting and zero at 50 then my second zero should be around 200 with 100 coming in a few inches high.

+1

Just make sure to verify your zero at 200.

I made a trip to range today to sight in my carbine. I used a laser before I left to get in ballpark. My Aimpoint was just about right on at 50 and few inches high at 100. I removed it and switched to the Matech set at 200 and it was about a foot low at 50, not even on the paper at 100.

I made two full turns down on the front sight post and it brought it up pretty close at 50 before a heavy down pour terminated the session. Is it normal to have to crank down the front sight post so much to get zeroed? Most of my other AR's have the base of the sight post pretty much even with the shelf. This one is down about a 1/16 of inch. BTW its a F marked sight. I would assume the Matech is set up for the F marked sight posts.

It is what it is.

You do what you need to do to zero the rifle.  There really isn't any predicting what any given setup is going to produce until you shoot it in.

Sounds like you are on the right track.

Thanks,

I was a little worried I might have tweaked something out of spec when I changed out the barrel and rear sight. It was a brand new LE6920 and did the mods before even firing it.

It shouldn't ever be an issue unless for whatever reason you would need to screw the FSP all the way up until it no longer catches the threads of the FSB. 

Thanks for all the help. I will not worry about it.