Help with scope being 3MOA off

[leclairk]

I’ve got a S&B PMII. Went to the range and the scope was perfect. Packed it in a pelican case and come out to Montana to hunt and when I checked my zero I was 3 MOA high. Windage was fine. Scope does not appear to have moved at all. I don’t have a Fat Boy with me to check torque values on the mounts. I have Seekins rings mounted to a picatinny rail. Any ideas?

 

[Dusty Stevens]

Sticky internals. Different altitudes

 

[243winxb]

Vibration from plane or car rides can make ajustments change. Sticky springs.

My rifle tipped over off the bags. Fell about 4" on to the bench top. Point of bullet impack went up 1 1/2" & a 1/2" right @ 100 yds. . Shot anoter group, no change.

Reset to zero. Stayed there ok. Did a scope test. Adjustments were repeatable and returned to original zero.

I would reset to your original zero & watch for any shift in zero.

A spring system presses the erector tube against the bottoms of the windage and elevation screws. When the adjustment screws are turned inward, they push the erector tube against the spring system; when the screws are backed off, the spring system moves the tube.

https://www.americanrifleman.org/articles/2015/12/1/how-scope-adjustments-work/

 

[joshb]

Jet lag?
Altitude change?
You did the right thing by taking some test shots!
A lot of guys don’t.

 

[Riesel]

I was going to say move back about 150 yards or make sure you shots are over 250 yards.

But I won't

 

[rhovee]

I just returned from Idaho and hunted pretty hard and had my rifle tip over on a bipod and hit the dirt. I’ll double check all mine and report back. I have heard of this before.

 

[KY_Windage]

I don't know (rifle case dropped?) but with all due respect, not being able to check that your ring screws are tight w/o a torque wrench is ridiculous. All rifle shooters should know what "about 15 in/lbs" feels like, along with 20, 30 and 40.

 

[leclairk]

I don't know (rifle case dropped?) but with all due respect, not being able to check that your ring screws are tight w/o a torque wrench is ridiculous. All rifle shooters should know what "about 15 in/lbs" feels like, along with 20, 30 and 40.

No wrench AND no bits. If I had bits I agree I could at least tell if something was loose enough to move. I think it’s the scope. If nothings loose I’ll send the scope back to Schmidt and Bender. Scope is barely a year old.

 

[Larry70]

I just checked Berger’s ballistics calculator and a 175 Gr 30 cal bullet zeroed at 500 feet will rise almost a inch at 5000 feet , don’t know what your set up is , something to think about

 

[KY_Windage]

No wrench AND no bits. If I had bits I agree I could at least tell if something was loose enough to move. I think it’s the scope. If nothings loose I’ll send the scope back to Schmidt and Bender. Scope is barely a year old.

If it is worth taking my rifle there, it is worth taking my small Rifle Tool Box with me. But of course, I learned that the hard way.

I really like the kits Chapman Mfg. sells, plus I carry sets of short and long hex tools, US and metric, and a few specialized tools and implements, like a loop of cord for taking a Rem. 700 bolt apart.

It is highly unlikely that there is anything wrong with your scope.

 

[leclairk]

I talked to Schmidt and Bender and they say it’s probably changes in atmospherics. They “very, very, very rarely have issues with the internals of our scopes.” So what do you think, zero’d at sea level and 70 degrees, checked at 3000 feet and 30 degrees, off by 3 minutes?

 

[rhovee]

No way it’s off that much. I zero at sea level. A few weeks ago I was in Idaho at 6k. Ranged a rock at 1512 yards that was 3/4 moa and drilled it. I have brought my rifles many times to MT to shoot at 1k on paper and it’s right on. Maybe 1/2 moa low at 1k when tuning. MT was around 3500 feet elevation.

 

[leclairk]

No way it’s off that much. I zero at sea level. A few weeks ago I was in Idaho at 6k. Ranged a rock at 1512 yards that was 3/4 moa and drilled it. I have brought my rifles many times to MT to shoot at 1k on paper and it’s right on. Maybe 1/2 moa low at 1k when tuning. MT was around 3500 feet elevation.

Agreed. I think they’re full of crap.

 

[johara1]

Wood stock?.... jim

 

[leclairk]

Synthetic

 

[leclairk]

Finally got my rifle back and checked everything out. All screws are tight EXCEPT when I pull on the scope I can see the slightest movement of the picatinny rail on the receiver. I assume that’s my problem.
Problem is I know I torqued that rail down and used blue loctite. So why is it loose?

 

[243winxb]

Blind holes? Screws bottomed out in short hole or screws to long?

Could to much Locktite, in bottom of hole, compress, giving false torque reading? A thread locker is mostly not needed. Imo.

 

[DirtySteve]

I agreed that a 3000 foot change in elevation is 1/2 to 3/4 moa max. Add less humidity and maybe 1 to 1 &1/4 MOA max.. I had my MK4 fall 3 feet onto concrete and land on a turret. Move the POI a mile in all directions. Rezeroed it and it has been fine ever since. So I am sure your scope is fine just experienced a shock of some sort.

Just read your other post... I had that happen to my 6.5 Creedmoor rifle it was driving me nuts till I checked the base..

 

[wedgy]

Bed your scope rail, many ways to do it but this will give you and idea;

 

[leclairk]

The more I look at it the more I wonder if that’s really the problem. I’m pushing and pulling on my scope pretty good and I’m seeing the tiniest little bit of separation between the rail and the gun. I’m not sure it’s loose as much as it’s just the physics of the way the rail mounts to the gun. I just need to go shoot the damn thing and see what the hell is going on.