knock scope turrets on the bench and POI shifts. Normal?

[777funk]

I noticed some POI shifting from session to session and in trying to narrow it down did some diagnostics. I knocked the barrel to one side on my sand bags and watched for POI shift... NONE. Then I did the same with the barrel vertically. NONE.

Next, I knocked the objective of the scope. No shift.

Last, and this was the problem, I knocked the windage turret adjuster (locking ring and knob type on a Centerpoint 4-16x40) and it shifted my POI by about 1.5MOA.

I assume this is not normal. Correct?

 

[Highcaliber]

Well... its normal for a $70 pellet gun scope. That scope is almost considered a toy. Can you tell us what type of rifle you have it mounted on?

 

[Float Pilot]

Old timers like me often tap (smack) the adjustment rings on rifle scopes after making an adjustment. Because the little indentations on some scopes will let the mechanism jump a few notches under recoil unless the little tooth is sitting down inside the notch.

Some cheaper scopes have problems holding zero under recoil because of this. I have never heard of a Centerpoint scope, so i have no idea.

I have also had a $700 Leupold 4.5x14 VX4 Boone and Crockett scope start to jump back and forth by an inch. I was obtaining two groups an inch apart as the scope guts went back and forth under the recoil of a 300 Win mag.
That scope went back to Leupold and they replaced it.

 

[Derek Zeanah]

That looks like a $70 scope, and sometimes you get what you pay for.

I don't really have much advice to give you here, as I'm something of a scope bigot. I have the prior version of this sitting next to me with an RMA to be disassembled and cleaned, and I'm in the process or swapping one of these with one of these on a new project gun. Ordered it this morning, as a matter of fact.

Sometimes good optics cost as much (or more than) good guns. In other cases there are some decent bargains out there, like Vortex and SWFA's Super Sniper brand which are hard to beat for value.

Value is the intersection of quality and price, and optimizing for one comes at the cost of the other most of the time, I'm afraid.

 

[777funk]

Sounds like even some of the expensive optics have trouble sometimes.

I use these on pellet guns by the way (nice ones though that are more accurate than many 22's). So recoil isn't the problem in this case although on my springers it most definitely is.

They do have a lifetime warranty but I am a little bit afraid that this is a feature and not a defect. I may buy a new one and return it if it's the same.

Glass wise (I have the original version not the one you linked to at Walmart), as in image clarity, it's not bad. I had a Bushnell Elite 4200 and I can see tiny caliber holes at 100 yards more easily with this than with the Bushnell.

 

[taliv]

Last, and this was the problem, I knocked the windage turret adjuster (locking ring and knob type on a Centerpoint 4-16x40) and it shifted my POI by about 1.5MOA.

I assume this is not normal. Correct?

if by 'normal' you mean common, then it is. happens all the time, although ime, more often when you hit the objective than the turrets. if you mean 'OK' then no, it's either broken or junk.

Old timers like me often tap (smack) the adjustment rings on rifle scopes after making an adjustment. Because the little indentations on some scopes will let the mechanism jump a few notches under recoil unless the little tooth is sitting down inside the notch.

the schools like thunder ranch and others used to teach people to tap the top of the turrets to help seat the screws in the leupold and other optics. if you didn't, your first shot would be off a bit and the recoil would seat the screw and your next shot would be consistent with the adjustment, but because your first shot was off, you'd mistakenly make another adjustment. good frustrating way to eat through ammo. sometimes i still do that, but i don't think it's necessary on most of the scopes i use today. they are however, all still just screws under the cover.

 

[docsleepy]

Oh, here we go again!
Yes, these are cheap scopes.
No, they probably won't hold up as good as A trijicon
As was pointed out, the Turrets are nothing but screws with threads, and depending on the quality of the threads and the fit to what they connect to, things can go awry.

Yes, I have them on a 7 mm 08.
Yes, I have them on several ARs
Yes, I even have one on a 50BMG
No, I really have never seen a zero shift that I could prove.

Yes, if I change what is under my rifles forearm, the recoil pattern will shift and the point of impact will shift. I typically see about one MOA if you make an extreme change and forearm rest resiliency.

I was at arrange the other day with the fellow who had a really tricked out A.R., and was shooting about 2 1/2 MOA groups, with a pretty good scope. yes me to try it and I shot a group that was about half the size of his, probably because I maintained a more consistent stance beside the bench.

He sure had a nice scope

When there are a whole host of variables , each with its own variance, the total error is probably the root mean square of all the underlying errors. Or maybe worse, it was a long time since I took statistics and probability. But the air into used by a less than thousand dollar scope must be kept in perspective with all the other errors that one is dealing with. As well as your desire not to have to eat cat food in retirement.