Frustrating trip to the range

[drvred]

I have been to the range several times with my AR with a red dot. I can shoot decent groups at 50 yards.
Purchased a Vortex Diamondback Tactical 4x12x40, installed it, and back to the range.
At 25 yards, trying to get on paper, I put 2 shots touching,and the third 2 inches to the right.
Moved to 100, still 2 shots almost touching and the third way right.( Usually 3-4 inches)
At the end of the day, everything went to crap, and I found that the mounts we're loose and sliding on the rail.
I can't figure out why the third shot was always a flyer, I assume trigger pull but each round looked good through the scope at firing.
Any ideas?
TIA
Rick

[MegademiC]

Do you dry-fire a lot?
How many rounds do you have you shot from it for accuracy?
Are you taking a break between shots? How is your breathing?

What gun/barrel/ammo? It may be near the capability of the rifle.
I would push it to 5-10 shots.

[drvred]

It's a Del-Ton 16" mid length.
I started with Independence 55gr.
Switched to Winchester 5.56 Nato. 55 gr.
Been away from rifles for 30 years, just getting back into it.
I am encouraged by the fact that I can put the first 2 of every group nearly touching each other, just throwing the third one almost exactly the same spot out (way out) every group is perplexing me.
I could see a random flyer, but this is weird.

[officerX]

So at what point in all the this did you tighten the scope mounts?


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[drvred]

I discovered it as I was packing up, by then the light was gone.

[GH41]

It's a Del-Ton 16" mid length.
I started with Independence 55gr.
Switched to Winchester 5.56 Nato. 55 gr.
Been away from rifles for 30 years, just getting back into it.
I am encouraged by the fact that I can put the first 2 of every group nearly touching each other, just throwing the third one almost exactly the same spot out (way out) every group is perplexing me.
I could see a random flyer, but this is weird.

You are doing good if you are consistently getting 3" 100 yard groups with that combo. You need to try different (better) ammunition. What twist is the barrel?

[drvred]

If I can get rid of the flyer, it should be significantly better than 3".
I hope the Winchester isn't crap, I have 600 rounds of it. :-(

[MegademiC]

Use that ammo for training.
Buy match ammo for accuracy testing. Dont use fmj for accuracy testing. Imi seems to make good stuff (otm).
If you have a 1/9 twist, try 50-60 gr vmax loads.

[GH41]

If I can get rid of the flyer, it should be significantly better than 3".
I hope the Winchester isn't crap, I have 600 rounds of it. :-(

The white box Winchester isn't terrible in most rifles but it isn't what I would call target ammunition. Tighten the scope and head back to the range. Use a target big enough that you can offset the windage adjustment so the POI is as far away from the POA as possible. Take your time and shoot 20 rounds trying not to look at where the bullets are impacting. This will give you a better read on what the rifle, ammunition and you are capable of doing. Repeat with a box each of 77 and 69gr match grade ammo. Keep in the back of you head that putting a scope on a basic AR 15 doesn't make it a precision rig. That's what they make steel plates for. For me it is more satisfying ringing 6" plates with cheap ammo than shooting small groups with ammo that cost a buck a round.

[everready73]

As stated above with that ammo a shot being off is normal. It is not match ammo and groups will not be great with it in most cases.

The loose scope mount is probably what did you in. Loctite (blue) the screws and torque to factory settings if you have a wheeler fat wrench (maybe borrow or take to a smith if you haven't mounted a scope in a while).

The other factor is your rifle.A Delton 16 inch midlength isnt a gun a would expect 1'' groups from at 100. If you can get around 2 moa that is probably more the norm. You could get lucky and have a shooter, but everything else needs to be gtg