How to tell if your scope is not holding zero?

L

lemming303

New member
I have two scopes in question. One is an old weaver that has seen at least 5000 rds on a lightweight 30-06. The other is a busnell elite 3500 that I used on my 338 Lapua for a short period. I put it back on my AR and I can't seem to get groups less than 1". So how do you know if a scope is messed up?
 
I'd suggest a lazer bore-sighter. Just make absolutely sure that you remove it before shooting again. Perhaps just load one round at a time into the magazine.

Hobie
 
My approach is just to swap the questionable scope with one I know to be good and do some test shooting off the bench. The downside is that a swap-out won't tell you much if you or your rifle are aren't capable of good consistent shooting or if you don't have access to a good shooting bench.
 
I don't recommend the laser at all. If you fire, clear, put in laser, pull out laser, load, fire again- what is that going to tell you with all the moving around that has been done? Lasers seldom are of any value to a useful distance and in my opinion are only meant to get the shooter on paper for final dial-in.

The only useful suggestion I have is to spend some benchtime with a known value scope. If your AR does no better with a scope that you know to be good (maybe one that came off of a friends rifle?) then you should be fairly sure the scope is off. As a note, I don't know of too many instances of a bad scope only allowing (up to) a 1" wander. If your rifle was shooting a 1/2" group before, then your scope is only wandering 1/2". So, if you have a 1/2" to 1" deviation, maybe we could look at other issues? Changed lots of bullets, powder, primers, weights of bullets or powders, changed brass?
 
That makes sense. Thanks for the help. I didn't really think about trying one of my other scopes because I spend so much time making sure they are lined up perfect when I mount them.
 
"I don't recommend the laser at all. If you fire, clear, put in laser, pull out laser, load, fire again- what is that going to tell you with all the moving around that has been done? Lasers seldom are of any value to a useful distance and in my opinion are only meant to get the shooter on paper for final dial-in.

The only useful suggestion I have is to spend some benchtime with a known value scope. If your AR does no better with a scope that you know to be good (maybe one that came off of a friends rifle?) then you should be fairly sure the scope is off. As a note, I don't know of too many instances of a bad scope only allowing (up to) a 1" wander. If your rifle was shooting a 1/2" group before, then your scope is only wandering 1/2". So, if you have a 1/2" to 1" deviation, maybe we could look at other issues? Changed lots of bullets, powder, primers, weights of bullets or powders, changed brass?"

Hard to argue with good advice.:)

I learn as i go. I have a Laserlyte system and it has allowed me to get on paper pretty well but as you stated, r&r the laser would introduce un-necessary variables.

Regards,

Hobie
 
Contrary to some, I doubt if many ARs are capabile of better than 1 MOA, especially if the loads aren't perfectly matched to the weapon. AND, it depends a lot more on the shooter than a lot of people seem to think.
 
Well Lemming did say he put it "Back" on the AR, it was just my assumption that he had it below an inch before. It was also that assumption that inclined me to think he rolls his own. Could be anybody's guess.
 
10-96 you are correct. I didn't have a finished load made for the AR yet, but even with factory Hornady ammo that usually shot 3/4", now shoots 1.5 or so. I figured the scope was suspect because I used it for about 100 rds on my Lapua, which obviously has a little stout recoil.

Winchester, I have seen quite a few AR's that were sub MOA, with decent ammo of course. You can't take American eagle or winchester silver tip ammo and expect good accuracy out of it....
 
Don't forget the trick of walking the scope around in a square pattern, to see if it returns to the same point. May or may not tell you something...

Shoot at target, click over to the right a couple inches and shoot again. Click down a couple inches and shoot again. Left, and up , etc, until you are back to the original aiming point. Ideally, you will end up with a nice square on the target.
 
Ideally, you will end up with a nice square on the target.
Click to expand...
Ideally, yes. However, if his setup is throwing 1.5" or so groups his end result could still be a tad bit confusing- Was it the scope throwing wildly in a semi-square pattern, or was it the rifle flinging shots out of the square?
 
Go back to the basics. IMHO,,, I would go back to the hornady ammo that shot 3/4" for you before. Then I would place a target downrange & center the crosshairs on a known area of the target such as the center of something that is easy to go back to. Set the scope adjustment off in elevation & windage a small known value, such as 6-clicks each way. Now put the cross hairs on the first reference point & fire a three or five shot group, keeping the scope centered on the reference point each shot. Your POI will be off but you will see the group. Aiming at at the center of a unshot reference point is easier than aiming for the center of a hole you previously shot. If you do your part, this should tell you if the scope is performing.
 
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