Zero drifting issue

[rocketdogbert]

Afternoon peeps. I  not sure this is the right section, so bear with me please.

I have a potential issue with a Vortex Strike Eagle 1-8x FFP, Primary Arms cantilever mount and wondered if any body has any observations or ideas.

Scope is on a .22lr KRISS Vector with a shortened barrel. Barrel has been correctly re-crowned and re-proofed, shooting is from a bipod.

The issue is zero is drifting between sessions.

Everything is torqued correctly, but every new shooting evening I have a large discrepancy in both elevation and windage.

Gun is cased immediately after use, transported approx 20 minutes in the car, then straight back in the safe.

It’s only being shot at 25 and 50 yards, shooting between 50-200 rounds per session.

Mount to rail and scope to mount are correctly torqued, I check every time the rifle comes out. Barrel has been off to be shortened, but is also correctly re-installed by gunsmith, It’s not loose.During every session, once re-zeroed, rifle is spot on, very very tight grouping, no drift

Short mags, nothing being leaned on

 

Any and all suggestions gratefully received.

 

ta in advance

 

John R

[ds1]

Best would be to try another scope that you know is reliable in a different mount on the rifle. It will indicate if the issue is with the rifle or not from the start.

If all is good with the rifle the mount is the next likely suspect - check it for cracks etc ( I had a Spuhr mount crack , so anything is possible). If possible try a different scope in the mount, it will indicate if the issue is with the mount or scope.

If the rifle and mount seem fine you might  want to check the scope with a collimator or try it on another’ rifle, if it’s clear that the scope is the issue -  a return to Vortex would be the best option - as far as I know it’s an unlimited lifetime warranty that’s not restricted to the original purchaser.

https://vortexoptics.com/vip-warranty

 

[rocketdogbert]

10 hours ago, ds1 said:

Best would be to try another scope that you know is reliable in a different mount on the rifle. It will indicate if the issue is with the rifle or not from the start.

If all is good with the rifle the mount is the next likely suspect - check it for cracks etc ( I had a Spuhr mount crack , so anything is possible). If possible try a different scope in the mount, it will indicate if the issue is with the mount or scope.

If the rifle and mount seem fine you might  want to check the scope with a collimator or try it on another’ rifle, if it’s clear that the scope is the issue -  a return to Vortex would be the best option - as far as I know it’s an unlimited lifetime warranty that’s not restricted to the original purchaser.

https://vortexoptics.com/vip-warranty

 

Thanks for the reply, I’m talking to Vortex about it. 

I like the idea of another scope, but it would mean borrowing one for a week or more, the only other scope I have I’ve only used once so don’t know for certain it’s absolutely right (it’s a 4-16x44 Vortex Diamond Back) Great idea though

[rocketdogbert]

I took the rifle out for a half hour drive to see if that was upsetting something, it doesn’t seem to be. 🤷🏻‍♂️

[Popsbengo]

Try shooting it once "re zeroed" and shooting groups then give the scope a good knock with your hand and try shooting again before doing anything else.  I had a friend with a similar problem and it was the Vortex scope internals jumping.

 If the scope is good I'll be surprised, except you say you checked the torque on the mounts - how did you do this?  I'm wondering if you're making the problem by upsetting the mounts ?  It's a longshot (no pun intended) but it's a strange one needing careful elimination step by step

[rocketdogbert]

27 minutes ago, Popsbengo said:

Try shooting it once "re zeroed" and shooting groups then give the scope a good knock with your hand and try shooting again before doing anything else.  I had a friend with a similar problem and it was the Vortex scope internals jumping.

 If the scope is good I'll be surprised, except you say you checked the torque on the mounts - how did you do this?  I'm wondering if you're making the problem by upsetting the mounts ?  It's a longshot (no pun intended) but it's a strange one needing careful elimination step by step

I have an electronic torque wrench, so I’m not over tightening anything, and I didn’t star pt checking until the zero started drifting, good idea though.

i think you’re right, I’ll need to shoot some groups, then give the scope a hand whack and see how it responds. 
 

At the moment I’m inclined to think user error somewhere, but where I don’t know

[Popsbengo]

4 minutes ago, rocketdogbert said:

I have an electronic torque wrench, so I’m not over tightening anything, and I didn’t star pt checking until the zero started drifting, good idea though.

i think you’re right, I’ll need to shoot some groups, then give the scope a hand whack and see how it responds. 
 

At the moment I’m inclined to think user error somewhere, but where I don’t know

you shouldn't keep torquing the screws again and again, if they're right leave them alone.  Best of luck

[rocketdogbert]

19 minutes ago, Popsbengo said:

you shouldn't keep torquing the screws again and again, if they're right leave them alone.  Best of luck

I’m not, I know, but thanks.. The digital wrench prevents that.

Again, Thanks

[ds1]

Rocketdogbert,

what's the upper to lower play like? I ask as the optic and barrel are on different parts. From what you say the grouping itself is fine. I don’t expect this  is your problem but worth a few minutes consideration from. Kiss Vector full-bore.

ps. (giving your scope a knock may indicate reticule movement but may also in this case indicate movement between upper and lower if there is any tolerance) a  collimator attached to the upper would isolate the scope effectively though if you want to give your scope a knock).

“I discovered an issue that may affect accuracy. There is play between the upper and lower receiver. If you twist the upper (rear) and lower (forward) grip in opposite directions, you will notice that a gap of about 1.5 millimeters appears between the receivers. Since the sights are on the upper, and the barrel is on the lower, an aimpoint error is induced.  

My rough calculations shows a potential error of +- 3 inches at 25 yards.  

In my opinion, there should be NO movement or play between the upper and lower. Especially since the barrel is on the lower and the sights are on the upper.  

I've been getting lousy groups at 25 yards from a bench rest, and I am not happy. “

[rocketdogbert]

2 hours ago, ds1 said:

Rocketdogbert,

what's the upper to lower play like? I ask as the optic and barrel are on different parts. From what you say the grouping itself is fine. I don’t expect this  is your problem but worth a few minutes consideration from. Kiss Vector full-bore.

ps. (giving your scope a knock may indicate reticule movement but may also in this case indicate movement between upper and lower if there is any tolerance) a  collimator attached to the upper would isolate the scope effectively though if you want to give your scope a knock).

“I discovered an issue that may affect accuracy. There is play between the upper and lower receiver. If you twist the upper (rear) and lower (forward) grip in opposite directions, you will notice that a gap of about 1.5 millimeters appears between the receivers. Since the sights are on the upper, and the barrel is on the lower, an aimpoint error is induced.  

My rough calculations shows a potential error of +- 3 inches at 25 yards.  

In my opinion, there should be NO movement or play between the upper and lower. Especially since the barrel is on the lower and the sights are on the upper.  

I've been getting lousy groups at 25 yards from a bench rest, and I am not happy. “

Thank you. I checked the play between upper and lower this afternoon.

I clamped the barrel in a vice, with a laser red dot in the barrel, and twisted the upper, checking the movement of scope/upper against lower/barrel.

It’s a really good idea, but it’s not the solution. The deflection at 50yds is less than an inch, and as soon as I release pressure on the upper it goes straight back to correct zero.

Thank you

[rocketdogbert]

I’m going to revive this thread. I’ve deliberately not used the scope/rifle combination for a couple of weeks, I’ll be using it tonight at 50yds.

At the moment, I’m disillusioned with the scope, so I’m after some possible alternatives, any ideas?

I’ll be setting a budget of up to £1500 absolute max but would love to spend a lot less, I’d like a 30mm tube, between 8x and 10x max mag, variable but doesn’t have to start at 1x.

It must be LPVO/short dot style

Reticle must be a cross hair style, would prefer holdovers, and would like first focal plane as well.

Any ideas?

[rocketdogbert]

Last update on this, scope went back to Vortex on Wednesday morning.

They received it at 12:30 yesterday, by 14:30 I had an email confirming it was faulty and a new scope would be in the post today.

What awesome service, you  can’t ask for better I don’t think.

[Popsbengo]

1 hour ago, rocketdogbert said:

Last update on this, scope went back to Vortex on Wednesday morning.

They received it at 12:30 yesterday, by 14:30 I had an email confirming it was faulty and a new scope would be in the post today.

What awesome service, you  can’t ask for better I don’t think.

Glad it's getting fixed.  Useful feedback

[rocketdogbert]

Brand new scope arrived from Vortex Optics U.K. this morning, amazing service

[Popsbengo]

13 minutes ago, rocketdogbert said:

Brand new scope arrived from Vortex Optics U.K. this morning, amazing service

Well, it is good service but there's often tails of Vortex scopes needing to be repaired so I wonder if  'make them cheap and repair as required' is the business plan?

[rocketdogbert]

14 minutes ago, Popsbengo said:

Well, it is good service but there's often tails of Vortex scopes needing to be repaired so I wonder if  'make them cheap and repair as required' is the business plan?

I agree, it may well be. But they are budget/medium priced scopes for the most part, so a no question repair/replace policy suits me.

I’d like a NF or S&B but can’t afford them 🤷🏻‍♂️

[TSG]

We use them at work. (Strike Eagles which get really knocked about.) They replaced everyone we sent back including the one that looked more like a banana. The glass quality is average although they are the IS new scope supplier for the SIG rifle. The more expensive glass is very good.( drums turn the wrong way of course but …)

Edited May 15, 2023 by TSG
Bracket missed

[Roy W]

Lots of people sing the praises of Vortex Customer Service. 

Not sure I've heard much about S&B's customer service, or Nightforce etc etc

I wonder why?

 

[ds1]

Look at it this way, if you are buying a second hand scope (particularly if it’s a higher priced unit) you have very little to lose with a Vortex - the scope is warranted for life. For me it would be quite an important factor say between choosing a Vortex Razor vs a S&B PM2. It’s also a reasonable argument over choosing to buy a second hand Vortex over a new Vortex.