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7/1/2006 3:36:15 PM EDT
I was at the range today with the intention of zeroing my RCO M4 ACOG, but ran into a small issue.  I wasnt sure if I should put this in the ammo section or the optics section, so I opted for this section as it is more optically related.  In accordance with the zeroing procedure for the ACOG, I was zeroing it today at the 100 yard line at the range and I was using Radway Green ammo to zero it so I knew the BDC will be configured correctly with M855.  At 100 yards, I would get a good 5 shot group 1 inch low and about 1 inch right, so I would correct 3 clicks right and 3 clicks up.  The next group would be pretty much right on top of the first group.  So I go and reverse my correction to see what happened, and the very first shot of the next group is a bullseye.  What recommendations do you guys have for ensuring that this thing gets zeroed right?  Is Radway no good to zero with?  Should I use some of the M855 I got from ADCO to zero it with?  I fired 3 groups with some 60 grain Black Hills VMax ammo and got similar results, but I didnt keep it up for long enough to tell if it was grouping better because I dont want to zero with that since it isnt close to M855. I need some help zeroing this thing, it is the second weekend I have tried, and I am getting frustrated.  Thanks.
7/1/2006 7:51:39 PM EDT
[#1]
no one has even a slight idea?  Please?
7/1/2006 8:21:13 PM EDT
[#2]
A 3 shot group is good for getting the zero 'in the right area' but it takes a 10 shot group to really confirm the center of the group.

With M855 ammo it's entirely possible to adjust your ACOG only 3 clicks and still hit to the same point since M855 isn't exactly match ammo.
7/1/2006 8:34:32 PM EDT
[#3]
i would say you were changing your sight picture slightly, but in any case an inch left and an inch low wint going to hurt too much
7/1/2006 8:41:57 PM EDT
[#4]
well I was using 5 shot groups for the zero, and it was still all over the place.  What should I use then to zero the ACOG to be in line with the BDC?  I dont think I have a choice.  I do have some AE 62gr FMJ which was compliments of the DEA, but I dont really want to blow it on this if I dont have to.  You think the AE stuff would zero almost the same as the M855, or will the steel penetrator in the M855 affect the zero between the two?  The M855 I have isnt PD or anything, I have some brand new LC from ADCO, and I got some left over rounds courtesy of the US Army.  I know either ammo I use will be first run ammo, I just need some direction in which one to use to get this thing hitting where I want.  I dont like how I will aim at a bullseye at 100 yards, and the bullet goes 2" high and left.  That could be the important difference in a pinch.
7/2/2006 4:58:26 AM EDT
[#5]
Using the 300 meter cross hair zero at 36 yards, move out to 100 and confirm. This is the directions that came with my RCOA4. (When I zeroed this way I was dead nuts on at 100)
7/2/2006 5:32:30 AM EDT
[#6]
it should be close with the RCO M4 then, right?
7/2/2006 9:36:49 AM EDT
[#7]
Should be, or at least close enough for you to make "finer" adjustments
7/2/2006 10:56:31 AM EDT
[#8]
Well, thanks for the help.  Got it dialed in as best I could today, used the 36 yard zeroing method with it, that is the best way as I found out.  Seems M855 is the best 62 grain ammo to use, but it is still no where near match grade.  I guess I am just going to have to take what I can get for now.  Anything near 62 grains should be close I think.
7/2/2006 11:03:01 AM EDT
[#9]
Your point of aim may be changing as your rifle heats up and cools down. Do your fine-tuning with a cool barrel.
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