I have the arms 40 BUIS on my LMT 14.5
I zero @ 25M with L Ap with M855 so do this mean I have a 25m/375m zero?
and Short range Ap of 43M/250M
I also have adtl. 500M/600M Horizon notch wich is cool?
I know all about 50yard zero so PLZ
There is no 'L' aperture with the ARMS #40 - unless you changed out the standard aperture for an A1 aperture?
Even then the 25/375 flip to 43/250 zero only works with 20" barrels (or dissipators).
Does this help?
Yes it helps!1
Im Still kinda cofused once again about my zero?
Should I zero with wich Ap.?
I got the arms 40 Pat. 5,553,292 HAS Standard M16A2 apertures with adtl 5-600 meter horizon line/notch
The smaller Ap has a Notch 500/600m for Leading and used for Long distance
I call the small Ap Longe range but it dont have the L marking?
The Ghost Ring Ap. is for like 0 to 200M and is mark 0-2
Why would it work with dissipator barrels and not other 16 inch barrels? Don't dissipators still have a carbine gas system, just hidden under the full length handguards?
The #40 does have 2 different apertures plus the horizon line.
When zeroed at reccommended distance:
small (200-300m) peep apertures
horizon notch (500-600 meters)
Mine is in the 2nd row!
The very 1st one!
Thanks for the picture
Because you're trying to use the A1 sight zeroing method with an A2 aperture - the two are nowheres near the same.
The one you intend on using. I find using the small aperture to 'get close', then switching to the larger one to finish it up.
My M4's ARMS#40 has a 8moa difference between the apertures (we just tested it saturday).
If you were to zero it at 25y with the small aperture, you would have a 390y far zero (with M193) and the large aperture would never cross the point of aim, and the bullet would stay between -1.5 to -2.6" till 150y or so. At CQB distances you'd have a consistant 2" offset. Interesting, but not useful to me IMHO.
Zeroing at 50 with the large aperture (for that nice flat IBSZ trajectory), produces a decent 20y/470y "long range" trajectory with the small aperture. To me this is more useful, but you should note the trajectory reaces a height of 18.75" at 270y or so.
Geometry my friend.
Gas system has nothing to do with it - it's sight radius. The change in the point of impact between the apertures is based on sight radius. The rifle length sight radius in particular, which the dissipator shares. The offset is nearly doubled when you go with a carbine sight radius.
For example each click of the front sight on an A2 rifle is 1.25" in the change of impact at 100y. With the same front sight on a carbine it's about 2" per click at the same 200y. The change in offset between the apertures would be similar.
Gotcha...I wasn't thinking about the sight radius.
I was thinking along the lines of velocity of the bullet effecting the zero.
Thanks for the explaination.
Forest thanks for trying to help me.
I would like to take advantage of the horizon Line/notch 500/600M
When zeroing a regular M16A2 at 25M you use the Smaller AP RIGHT?
I dont want to zero at 25y?
I do want to zero @ 25M so I can take advantage of the 500M-600M Horizon Notch. Dont know wich Ap.
Also my Eotech 551 has the 50yard zero wich sits on my LMT M4
So would everyone else. If you can figure how to get it to work let us know please!
Because a 25y near zero produces a 375M far zero with M193, and the rounds gets rather high in the middle. M855 isn't much better.
When you figure out how it works let us know. I tried using it like a notch sight (like with my Winchesters) but it's too close to the eye to work that way. If there is another way to use it I'd really like to know.
If you prefer to zero at 25M then go for it. Just spend some time on a KD range at various distances and learn where the bullet will strike.
Forest I email ARMs and asked how to take advantage/use there line notch?
My range is only 200 yards and about 220yard at Berm.
I dought I will ever get to find out!
The 50yard zero works great at the BERM with ML2/551 I can hit Tin Cans all day long with that 50yard zero. the tin cans are old soup cans that shine real easy in FL sun!
I zero with M855 at 50yards and the Black Hills 77gr. is right on it at the berm 220yards or so!
so it might be easy on the pocket useing M855/SS109 bullet rather M193
But it was you and chuck in 2001 who told me all about the 50 yard zero Thanks!
I try to pass it on at the range but get odd looks