Noob ? - DPMs LR-308 AP4 Sighting In ACOG

[StrongCo]

Hello all. New to NES - moved here from Midwest and recently purchased a gun I'd been eyeing for some time.

16in DPMS LR-308 AP4 w/ ACOG scope - got it last week and have shot about 50 rounds through it. Shoots low and left - any reccomedations/experience on sighting in AR type rifles w/ ACOG scopes?

Any reccomendations on where/what to purchase for bench rest or access to assistance in "tuning the rifle"?

Thanks in advance for the help!

 

[Admin]

Welcome to NES StrongCo. Have you made any elevation or windage adjustments to the scope?

 

[hminsky]

Hello all. New to NES - moved here from Midwest and recently purchased a gun I'd been eyeing for some time.

16in DPMS LR-308 AP4 w/ ACOG scope - got it last week and have shot about 50 rounds through it. Shoots low and left - any reccomedations/experience on sighting in AR type rifles w/ ACOG scopes?

Any reccomendations on where/what to purchase for bench rest or access to assistance in "tuning the rifle"?

Thanks in advance for the help!

I am assuming from your question that you tried adjusting the elevation and windage on the scope and you still couldn't get the dot to coincide with where the bullets were hitting the target?

If you're still on paper, at something like 25 yards, and the scope adjustments are all the way pegged at one side or the other, you might have put the scope mount on improperly. Try moving it up a notch or reseating it.

I had an experience that is probably very very rare but it was confusing as hell. I had a branch new EOTech sight. I mounted it on my AR15, and could not get it to sight in, no matter how much I turned the elevation knob. It turned out the EOTech was defective, there was a mirror inside that they had glued in with what must have been a bad batch of glue, and the mirror slid off its mount enough to make it impossible to sight in. But I didn't know that until later.


I was really confused, because I had never used an EOTech before, and thought I was mounting it improperly. After screwing around for a long time, I called them and described the problem. They were puzzled, but they sent a replacement right away.

They didn't actually want the defective unit back for some reason, so I took it apart and discovered what the problem was. The glue they had used on the mirror had never set, it was still kind of liquid and flowing.

 

[StrongCo]

Welcome to NES StrongCo. Have you made any elevation or windage adjustments to the scope?

No adjustments performed (yet)

I plan to "barrel" sight as first step...but I wanted to gather other's experiences/info prior to begining...this is my 1st AR-type rifle

 

[StrongCo]

I am assuming from your question that you tried adjusting the elevation and windage on the scope and you still couldn't get the dot to coincide with where the bullets were hitting the target?

If you're still on paper, at something like 25 yards, and the scope adjustments are all the way pegged at one side or the other, you might have put the scope mount on improperly. Try moving it up a notch or reseating it.

I had an experience that is probably very very rare but it was confusing as hell. I had a branch new EOTech sight. I mounted it on my AR15, and could not get it to sight in, no matter how much I turned the elevation knob. It turned out the EOTech was defective, there was a mirror inside that they had glued in with what must have been a bad batch of glue, and the mirror slid off its mount enough to make it impossible to sight in. But I didn't know that until later.


I was really confused, because I had never used an EOTech before, and thought I was mounting it improperly. After screwing around for a long time, I called them and described the problem. They were puzzled, but they sent a replacement right away.

They didn't actually want the defective unit back for some reason, so I took it apart and discovered what the problem was. The glue they had used on the mirror had never set, it was still kind of liquid and flowing.

As stated - no adjustments yet - just gathering any info/experiences that I should know about prior to sighting in....Bascially anything to "watch out for" on the ARs or ACOGs and any reccomendations as far as bechrests, ranges in Southern Maine, groups,....etc I shoot right now in my backyard and adjoining nature preserve.

 

[newenglandjeff]

Some things about the acog that may not be in the manual-

-If you are mounting it on mil-std rails, always mount it in exactly the same place. Otherwise your zero is useless. When you mount it, put it in position and apply forward pressure as you tighten the knobs. This eliminates "play" and will help you get back on target faster if you have to take the scope off. I have used this method everytime and have been on or close to zero every time I have removed my scope.
-choose a mounting position that gives you the proper eye relief. This is based on the individual operators cheek weld, which varies between each shooter/rifle/scope combo. Basically just because you see somebody mount thier acog in one position does not mean its right for you.
-when making adjustments with the acog, you need to do at least one of these two things; 1) make 1 extra click in the direction you are going and then back it off that 1 click. 2) when you make an adjustment give your scope an open palm smack on the knob you just adjusted. These scopes are rugged, they can take a little smack. This method was recomended to the USMC by a Trijicon rep. Its supposed to help seat all the internal mechanisms after an adjustment.

 

[Rob Boudrie]

I suggest you consider getting the new ACOG rail mount from JP - very click looking, and allows easy removal an re-installation without loss of zero.

 

[StrongCo]

Some things about the acog that may not be in the manual-

-If you are mounting it on mil-std rails, always mount it in exactly the same place. Otherwise your zero is useless. When you mount it, put it in position and apply forward pressure as you tighten the knobs. This eliminates "play" and will help you get back on target faster if you have to take the scope off. I have used this method everytime and have been on or close to zero every time I have removed my scope.
-choose a mounting position that gives you the proper eye relief. This is based on the individual operators cheek weld, which varies between each shooter/rifle/scope combo. Basically just because you see somebody mount thier acog in one position does not mean its right for you.
-when making adjustments with the acog, you need to do at least one of these two things; 1) make 1 extra click in the direction you are going and then back it off that 1 click. 2) when you make an adjustment give your scope an open palm smack on the knob you just adjusted. These scopes are rugged, they can take a little smack. This method was recomended to the USMC by a Trijicon rep. Its supposed to help seat all the internal mechanisms after an adjustment.

NE Jeff - Thanks - I'll try that - I barrel sighted it and shot a few rounds yesterday - ran out of daylight by the time the "chores" were done

I'm now about 2in high at 25m but great grouping.... - so I'll adjust and report back!

 

[Rob Boudrie]

I'm now about 2in high at 25m but great grouping.... - so I'll adjust and report back!

2" seems like a lot, but he ACOG has a wide adjustment range. I am a bit puzzled, however, how one can determine you have "good grouping" at only 25m.

 

[StrongCo]

2" seems like a lot, but he ACOG has a wide adjustment range. I am a bit puzzled, however, how one can determine you have "good grouping" at only 25m.

Are you trying to be helpful....?
Maybe I can explain - I take the rifle out of the case -load mag, chamber round, rest on bench, sight target, flip saftey off - actuate trigger - repeat steps several times...

Bullet impact at target is centered, but about 1.5 ~ 2in high (I have not measured it yet w/ a calibrated device ) but the impacts are consitent in their location on the paper - does that explain my reference to tight grouping?

got to run - going skiing.

 

[Supermoto]

What I believe, Rob means is that a 25m you are always going to get a good grouping because you are so close to the target. 100-300 will give you a better test of the rifles accuracy, 300+ will test your accuracy