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
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.
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.
So at what point in all the this did you tighten the scope mounts?
My iPhone XS Max is better than your android!
I discovered it as I was packing up, by then the light was gone.
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?
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. 
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.
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.
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
Yeah-
At the end of the day… I found that the mounts were loose and sliding on the rail
The bullets in that ammo aren’t in the same arena as a good quality SMK or Vmax. If the mounts/rings are tight, the bullet is the next piece of the puzzle.
I was sure I had misread the question. [emoji23]
Nothing of value was learned during this range trip. Properly secure and torque your optic and try again…
We’ve had bases loose where you could not feel it, but once disassembled, rub marks were visible where things were not really as tight as they felt.
Oh ditto. Cough…LaRue…cough.
Sure. I think that’s what was going on for most of this guy’s trip. Optic is staying on…but shifting every shot, and at 25 yards it’s so close that we can’t really tell what’s happening nor from what especially with the loose optic.
My have lived this nightmare for several weeks in a row before discovery. Your lucky it came way loose fast. I was warned just last night to rockset or loctite my Ruger Precision Rifle ( RPR ) base down. When I checked it two screws were kinda tight and two were barely tight. Not to derail, but if you own an RPR, lock em down.
For that matter, if you have bases, lock them down.
PB
Exactly. This is the biggest variable in the whole equation. Don’t worry about other variables until you’re sure this one is fixed.
BTW, I’d go with 5 shot groups instead of 3. You’re far more likely to get lucky with a 3 shot group. You’re not likely at all to get lucky with a 5 shot group and the results of separate 5 shot groups are much more likely to be similar, all else being equal.
Ok tightened and Loc-tighted bases, went back to the range yesterday.
Sighted at 50 yards, no crazy flyers, then moved over to the 500 yard steel range.
Wore the 300 yard target out.
Well done, how did 100 yard shooting go? 50 yards is ok, and steel is fun to hit but doesn’t always tell extreme accuracy. But there is no doubt your well on your way.
PB