Misaligned scope base options

[bluespruce]

I scored a pretty good deal on a nice Nikon to upgrade my current scope which I had mounted for me for 15 or so years ago. In that time, I've figured out how to mount scopes myself. Anyway, this is going on a long action model 70 and since the scope mounting length was significantly shorter than my current ring spacing (Leupold rings w/ rear windage base), new rings and bases are required. I've had good luck with Talleys on other rifles and a set of extended Talley lightweights should put everything pretty much right where I want it.

Simple right?
I got everything ordered but didn't get around to do actually installing anything for months - a newborn, work travel, and then this sneaking suspicion I probably shouldn't do this right before hunting season. That suspicion was well founded. It turns out the front and rear receiver mount holes are not aligned. Basically, when looking down the barrel, if the rear holes are at 12:00, the front are at, say, 11:00. Maybe not that bad, but you get the idea. I test mounted the scope anyway and it results in a pretty obvious misalignment between the barrel and scope (scope is pointing left of the barrel). I don't remember the gunsmith that installed the original scope mentioning this but I think that explains why he used windage bases.

So it appears I need windage bases, however I also need to bring the front ring back at the same time. It seems my options are to either have the receiver redrilled correctly (I'd likely remount the old scope before I go down that route) or use Leupold extension rings but frankly, those look pretty cobbled together. Do the extension rings hold up? I've seen mixed reviews. Any other options that I'm not thinking of?

 

[dirtclod Az.]

Remount your old scope,then mount your new setup when time allows.Less headaches
that way.

 

[bluespruce]

Remount your old scope,then mount your new setup when time allows.Less headaches
that way.

I've finally got the time. I considered doing it before hunting season as I finally had time then too but decided to wait in case I encountered a problem. I guess I've had too many of those quick little 10 minute jobs turn into royal PIAs.

 

[Don Fischer]

Guess I don't understand. You want to remove one scope and put on a new one but you want to change the base's and rings too? Then even though the base's and rings worked with the old scope for 15yrs, they won't work with the new scope? Is that it?

 

[bluespruce]

Yes, thats correct. The old rings are standard Leupold rings/bases and are spaced something like 6.0" apart. My new scope only has 5.5" between the objective bell and eyepiece for mounting.

I anticipated that issue so I got new one piece ring/bases (Tally Lightweight) which gives me the spacing i need, however, in the process of mounting, I found out my receiver mounting holes are not drilled correctly i.e. front and rear holes don't line up. There is no adjustment in these rings/bases so they don't work.

Basically the new one piece ring/bases won't work due to the receiver hole misalignment and the old rings/bases won't work due to the new scope mounting length.

 

[Don Fischer]

Ah. The old mounts worked for 15 yrs and then trying new base's and ring's you found a problem. Probably the standard base's rings for the rifle will work but you might need and extension ring. I had to do that on my mod 70 long action to get my 2-7x scope to fit on it. Now if you can see a problem like alignment of the holes in the receiver then that would really be a problem. But still they worked that way fine fr years. maybe use the same base's and get an extension ring for the rings. I know with the one I got there still wasn't a lot f room to move the scope but I did get it mounted and it works!

 

[bluespruce]

There is actually a misalignment in the receiver holes. I think the gunsmith was able to use the windage adjustment and lapping to cover up that misalignment.

If the new scope would have fit in the old rings, I don't think I'd have noticed. I'm just trying to figure out what options I have --- seems like the extension ring is about it.

 

[cahunter805]

If you don’t want to have the holes redrilled and enlarged then I’d say use the windage adjustable bases with extension rings.
Have you tried to use the talleys and see how far out of adjustment the scope was? Sometimes things look much worse than they are and you might be able to get zeroed with a minor windage adjustment.

 

[sneakypete]

I believe all you need is a wind age rear mount?

 

[ol_spark]

Maybe check hole spacing to see if a one piece picatinny type base would fit. Then get Burris Signature rings with adjustable inserts. They can generally be turned to compensate for the misalignment you describe. The picatinny rail should allow you to move rings to appropriate position. Or get extension rings as suggested.

 

[D4570]

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Check in to these, My 6mm rem has the receiver hole drilled off-center too.

 

[Seamaster]

Leupold offers a set of Standard bases (adjustable) with a reversible front base that works well for short scopes. They will give you all of the adjustment you need and correct the misaligned holes. Reversing the front base changes the spacing about an inch.

You can get a complete set of rings and bases for about $50 that will include the reversible front.

 

[bluespruce]

Maybe check hole spacing to see if a one piece picatinny type base would fit. Then get Burris Signature rings with adjustable inserts. They can generally be turned to compensate for the misalignment you describe. The picatinny rail should allow you to move rings to appropriate position. Or get extension rings as suggested.

I doubt a 1-piece rail would fit due to the misalignment between the front and rear holes. I might be able to get it to fit just using 2 of 4 holes but that seems like trouble just waiting to happen. The Burris rings are sure interesting. A 2-piece rail where the front can be reversed (looks like Warne makes one) with Burris rings could work.

Leupold offers a set of Standard bases (adjustable) with a reversible front base that works well for short scopes. They will give you all of the adjustment you need and correct the misaligned holes. Reversing the front base changes the spacing about an inch.

You can get a complete set of rings and bases for about $50 that will include the reversible front.

I'm not sure how I missed the reversible bases when searching the Leupold site. That would work and looks like a far better solution than extension rings.

I think either this or 2-piece rails and Burris rings will do what I need. Thanks to everyone for the input.