Problem staying at zero with my scope

[pschorrXD]

Hi Everyone,

I have a Bushnell ET1040 (Elite Tactical Fixed 10x by 40mm) and its having trouble staying on zero. It seems like after every shot and after every adjustment I made when I went to Angeles this past Wednesday it kept shooting low and to the left. I made sure everything was tightened down before the range and while I was at the range. I had this same problem on my Bushnell Banner 6-18x50, not necessarily low and to the left but it would not hold a zero.

This is becoming a real annoyance. I really do not want to keep plugging money into sighting in my scope. Any help would be greatly appreciated.

Update as of 6/14/13 : Went to the range, I think its more the ammo that Im shooting at this point. Its milsurp .308 stuff. I plan on buying a couple boxes of 168 or 175gr fed match kings and trying that out. Also im shooting it out of a savage 10fp.

[HK Dave]

Can you describe your zeroing process?

Did you have anyone else try shooting it?

Can you describe the gun you are shooting.

What kind of ammo were you running?

[pschorrXD]

Can you describe your zeroing process?
I bore sighted the rifle at 25 yards. Took one shot. Was low and left. Adjusted to center of target and then fired again. Did this for like 30 shots and was consistently low and to the left except for a couple of shots.
Did you have anyone else try shooting it?
I did not, my brother and I were there but bolt guns arent really his thing.
Can you describe the gun you are shooting.
Savage 10fp chambered in .308. I have the stock that it came with still on it with utg high rings.
What kind of ammo were you running?
It was bulk ammo I bought from a calgunner all brass boxer primed. I know its not match but at 25 yards id expect it to be pretty much dead on.

[HK Dave]

You sure the reticle is moving when you make adjustments? If every time you make an adjustment to match low left, and it stays at low left... there's a chance your turrets aren't working.

It doesn't sound like a mounting problem, as that would make your rifle shoot all over the place.

I could see it being a trigger pull issue, such as a flinch or where the web of your trigger finger is connecting with the trigger... and at what angle it's doing it... but at 25 yards, with a scope shooting low left despite turret adjustments... my guess is still scope.

Lock your rifle down (your scope really) so it doesn't move and twist the turrets while aiming at something with your reticle and see if it moves... make BIG adjustments.

[pschorrXD]

I did the best that I could to make it stable and moved the elevation and windage and seemed to work properly. I did grab my 1/4" torque wrench and torqued the rings down to 65 in/lbs just now and noticed they went a bit before actually stopping. Could that be the reason?

[Coyotegunner]

Ok its not holding zero at 25 yds??
Everything is torqued and the rings are of course in their respective slots etc.I have seen guys with this complaint have 1 of their rings pulled out of the mount).Make sure the action is snug on the screws to the stock as well.

At the range:Pull the bolt out of the gun.
Set it up in a solid mount.I use a Caldwell.You can do fine with a few towels rolled up under the forend and under the pistol grip.
Boresight the barrel to the crosshair at 200yds on something round like a paper plate.After doing this check your tracking on your scope,by turning things back and forth while you watch your reticle on a target.Alot of scopes do not match 1click/1/4" or so forth.Re zero to the 200yd target after your scope looks to be tracking OK.
With a clean piece of cardboard at 50 yds shoot,adjust,shoot,adjust,shoot,adjust.3 rds should be sufficent to get it hitting close.
Now go to 100yds on your target.I like mine zeroed at 200yds.Repeat shoot,adjust 3 more times.
If not start over again with what may be defective or loose.
Stability,I hope is your only problem,but you will know if is you when you do that tracking test at 200yds.
Ammo may have variance as well.
It seems you have quality equipment to start with.
Good luck

[pschorrXD]

I plan to go out and shoot again as soon as I get my car fixed. stupid p0335 code. I will keep you guys updated. I also have to order another set of rings because the back ring base screw is stripped now (I guess I torqued it too much with my wrench). I have some hornady 110grain fpd but id rather not use it for target practice (doesnt hurt to know how it shoots though). I usually go to angeles so I would have to bore sight it at 100 yards again.

[mycrstuff]

Make sure the right size screws were used for your mount. I had one rifle that the mount came with 8x32 screws and the gunsmith used 6x48 screws. The difference in the diameter caused a space between the scope mount holes and the screws. That space allowed movement of the base back an forth and caused the screws to be sheared off after 20-30 rounds. The scope went flying over to the next bench.

My first clue to there being something wrong was when I adjusted the scope and the rounds would move in the opposite direction from where the point of impact should have ended up.

[ExtremeX]

I did the best that I could to make it stable and moved the elevation and windage and seemed to work properly. I did grab my 1/4" torque wrench and torqued the rings down to 65 in/lbs just now and noticed they went a bit before actually stopping. Could that be the reason?

65 in/lb seems a bit excessive for torquing down the rings.... On average across the brands of mounts I buy I typically see 25 in/lb to 32 in/lb torque specs for rings.

With that said, I doubt that is the root of the problem.

Side Note: Over torquing rings may cause damage to the mounting hardware, screws,or scope tube itself.

[ExtremeX]

Lock your rifle down (your scope really) so it doesn't move and twist the turrets while aiming at something with your reticle and see if it moves... make BIG adjustments.

+1

1/4" MOA Clicks...
4 clicks = 1" @ 100 yards.
16 clicks = 1" @ 25 yards.

Like Dave said.. I would lock the scope in place, and ride the turrets to make sure everything is tracking well. You can get a ruler or print out a 1" square grid and place it at 25 yards in your home or backyard and ride the turrets to confirm the scope is tracking true.

[postal]

65 in/lb seems a bit excessive for torquing down the rings.... On average across the brands of mounts I buy I typically see 25 in/lb to 32 in/lb torque specs for rings.

With that said, I doubt that is the root of the problem.

Side Note: Over torquing rings may cause damage to the mounting hardware, screws,or scope tube itself.

Agree 65"/lb is WAY too much for rings...

This actually could be the source of the problem all by itself.

Depending on the quality/level of the base, quality of the rings, it could very likely be putting pressure on the scope tube itself. Bending the scope.

Add 65 in/lbs of ring pressure to that....

It quite likely locked up the inner workings of the scope.

Turning dials, but nothing inside the scope is moving because it's all jammed up.

OP. Nothing on your rifle should be torqued to 65 inch pounds except the action screws *IF* it is pillar and glass bedded. Without pillars, you would set below 65 even on action screws. Nothing scope wise should be over half that.....

I expect that is the root problem.

However, we still did not fully rule out your scope itself.

It should be mounted on a different rifle with correct torque to verify the scope is working properly.


--edit---
Re read your posts, a savage with factory stock (with pillars) action screws should be anywhere from 25 (factory recommended which seems light to me....) up to about 45-50 ish inch pounds. play with it and find out the sweet spot where the groups tighten up.

All scope hardware is different depending on manufacturer, and if it's steel or aluminum.....
Generally, serious steel rings, the cross bolts can hit in the neighborhood of 35 inch, most anything else, 25 inch for any and all screws related to rail/rings. You nearly tripled the pressure on your scope. I expect that, along with a warped/unlevel base put pressure on the scope tube which locked up the internals.

[ExtremeX]

OP told me via PM 65 in/lb was for the scope rings to the scope base.... but I still feel that's still too much.

You are right, my action screws call out for about 65 in/lb on my AICS chassis. I don't know what is typically for base to rings, as most of my mounts are QD or DNZ mounts.

He mentioned the rings being torqued to 15 in/lb which I feel is on the light side considering what I typically see from other scope ring manufactures.

OP, I would re-mount the scope and mounting hardware. Read online and use best practices when mounting the system. If you are confident the mounting hardware is not part of the problem, then confirm scope tracking via what I said above.

If all that checks out, the scope may in fact have an internal fault which is presenting itself after recoil...

[postal]

OP told me via PM 65 in/lb was for the scope rings to the scope base.... but I still feel that's still too much.

You are right, my action screws call out for about 65 in/lb on my AICS chassis. I don't know what is typically for base to rings, as most of my mounts are QD or DNZ mounts.

He mentioned the rings being torqued to 15 in/lb which I feel is on the light side considering what I typically see from other scope ring manufactures.
.

Every manufacturer is different, and if its steel or alu... but generally, anything scope base/rings is concerned, 25" is a safe and common bet. Some robust steel components could go higher, but it depends on the brand/model/material, and also if it's a 1 piece base or 2 piece.... (OP picture shows 2 piece) quality of the base for a 1 piece, (to ensure straight level) if the base was bedded or not... bedding helps insure it's stays straight and level.... if the rings were lapped, etc...

There are a lot of variables....

Easy cheat- call 25" good, Use quality parts, bed the base, lap the rings.


------edit---------
scope should be removed, place in a vice or something, and check the clicks like Extreme said. I'd pull it from the rifle and place LIGHTLY in a vice just to hold it pointed at something WITHOUT crushing the crap outta it....

[G60]

Badger recommends 65 in/lb for their rings to base, and 15-18 for the cap screws. seekins recommends 55 for rings to base an 15-25 for cap screws.

[ExtremeX]

scope should be removed, place in a vice or something, and check the clicks like Extreme said. I'd pull it from the rifle and place LIGHTLY in a vice just to hold it pointed at something WITHOUT crushing the crap outta it....

I actually have a block of wood (2x4) with a old scope base screwed to it just for this very purpose...

No need to remove the rings, just mount scope and secure the 2x4 with wood working clamps and conduct the test.