Scope runs out of adjustment until rings placed closer together. Why?

OK, here’s a riddle for you. Last year on a prairie dog trip, I foolishly left my Savage Axis 22-250 on the tripod/cradle while glassing the next place to move and shoot. Bad Grouse! Bad Grouse! Of course, a gust of wind knocked the tripod over and the rifle fell 3 feet to the dirt. After that, I could not get the scope back into adjustment both L/R and Up/Down. Clearly, something was bent. Luckily I had a backup 250.

Back home in the comfort of the Grouse Firearms Diagnostics Lab, I determined that the 2-piece Weaver base setup was bent such that the front base was not in alignment with the rear base. The front base unit has a twist along the long axis that is clearly seen when it was removed and placed on a flat surface. The scope showed no signs of damage. OK, we’re in business, I thought.

I did the following:

– Replaced 2 piece base with 1 piece Weaver base.
– Replaced rings with double strap Weaver rings.

After all this work, using a laser bore sighter, I was still out of L adjustment. The scope could not be adjusted to the left enough. Absolutely everything seems to check out using guides, straightedges, levels, etc.

It’s the scope! Yep, I hear you, that’s what I thought too. Until…

My last ditch idea was to move the rings closer together. The scope is an old-style Bushnell Elite (Japanese made, excellent optics) and it is a 6×24 so it is very long. I had the rings almost as far apart on the base as they can go, over 6 inches ring to ring.

So I moved the rings about 4 inches apart on the base.

Instantly everything worked! I have plenty of leftward adjustment now, I got it right on the dot and still have 30 clicks leftward adjustment to spare. I have checked and rechecked this setup. All components are properly fitted, crosshairs are leveled, nothing is “wrong” with the mounting such that this problem is somehow “fixed” by a bad mounting job that will come undone later.

But WHY????

Now this is bugging the crap out of me! What the heck CAUSED this to work???? I love solving a problem, but only if I understand what actually solved it. It makes me nervous to have a “solution” just drop out of the blue especially considering this move should have made no difference.

The base does not curve to the right. If it curved that much, such that I would run out of left adjustment on the scope, it would be visible to the naked eye. Even with a Starette machinist straight edge, checking multiple places on the base, I can find no curvature.

What could it be that caused this problem to suddenly go away just by moving the rings closer together?

Grouse

Buy an SWFA and move on!

Have you shot to confirm your L & R are horizontal and everything is still square?

Mine has hit the dirt like yours, in the exact same scenario, and shooting straight as can be. (3wks ago…oops!! )

Have to ask, what is an SWFA?

If we’re talking about replacing the scope here, I would do it if I thought the scope was bad. I was really close to doing just that, but as I’m sure you understand a quality 6×24 does not come cheap. IMO these Japanese-optics Elites are some of the last good deals out there in terms of high-magnification non-Chinese-made scopes.

No, I have not shot it yet. Maybe this weekend.

I have “bump tested the scope to see if there is something loose inside the scope that could be causing it to come easily in/out of adjustment. No dice. Scope crosshairs stay right on the little red dot of the boresight.

Also, the “solution” is repeatable. I have taken the scope off, put it back on, etc. Problem stays solved as long as I do not move the rings.

Grouse

Is there a possibility that somehow the ring dented or slightly bent the tube of the scope? So by moving the ring location, you managed to straighten everything out? That’s my guess.

404 ERROR wrote:

Is there a possibility that somehow the ring dented or slightly bent the tube of the scope? So by moving the ring location, you managed to straighten everything out? That’s my guess.

Hmmm. We may have something here. I’ll have to look carefully tonight and take some measurements with a micrometer. As a twist on your theory, I could also see the tube being not “dented”, but rather “oval-ed”. Hmmmm…

Excellent thinking!

Grouse

My immediate guess based on your accounting of attempted repair is a bent ring.

Easy explanation – the further the two contact points are apart, it will emphasize the problem. More specifically, I would anticipate the front ring to be bent

TheFamousGrouse wrote:

Have to ask, what is an SWFA?

If we’re talking about replacing the scope here, I would do it if I thought the scope was bad. I was really close to doing just that, but as I’m sure you understand a quality 6×24 does not come cheap.

Not cheap, no. I was just giving you a little grief.

https://swfa.com/optics/riflescopes.html?brand=SWFA+SS

Randy Wieland wrote:

Easy explanation – the further the two contact points are apart, it will emphasize the problem. More specifically, I would anticipate the front ring to be bent

So you’re thinking I may have gotten a bad new right out of the box?

Rings check as level with a straightedge, but I did not check for twist. So that’s another possibility.

But it’s hard for me to see how a ring would be so badly twisted that it’s more than 8 MOA out when mounted forward farther, but yet this is not visible. The scope sits perfectly in the rings.

Could be, though. Good suggestion.

Grouse

Is the scope tube one piece or do the front and rear portions of the tube fit into the turret housing? If the tube is multiple pieces [being an older scope] is it possible that the front portion got jarred enough to shift it in the housing?