Shimming scope bases on a NH Model 70

T

Techball

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I got an stainless model 70 ultimate Shadow used off a sponsor here recently and was very surprised to see that the rear receiver top contour was not ground symmetrically. This is a 7 digit serial late New Haven production so I guess that rumour about quality decline around 2003-2006 is true. When bases are on the rear one tilts right. I’ve shimmed it back with I think 10thou (0.25mm) brass shim stock. It’s a lot closer based on checking with scope alignment bars, close enough for further lapping. I’m pretty set on using Talley lightweight rings so I think shimming is the way to go.

Anyone else dealt with this? I heard about miss aligned holes but this contour issue is a first for me. Should I bed the shin into the base? Is that done with bedding compound between the shim/base and release agent on the receiver? The clamping pressure holds the shim fine but I would like to learn from more experienced folks here.

I will get some photos when I get the right rings (I got low rings but I think extra low is a better fit for my eye alignment).


Thanks.
 
If it were mine, I would have it ground to the proper contour at your local machine shop. There should be several in Calgary that can to the work.

If you're extremely handy and extremely careful, you could use a very fine file and stone to profile it properly yourself. Very tedious and if you aren't comfortable with it, don't attempt it.

There are some good smiths in Calgary that could do it for you as well.

You could also ship it to Bits of Pieces, they can do the job, but I've heard they're extremely busy right now.
 
Although I don't doubt your receiver is not right, the fault may be in the base as well. I've had a bunch of bases which were high on one side.
 
Leeper said:
Although I don't doubt your receiver is not right, the fault may be in the base as well. I've had a bunch of bases which were high on one side.
Click to expand...

Yeah, I thought that was the case at first but three sets of bases all showed the same issue. You can see the receiver contour sloping more on the right with your naked eye!
 
bearhunter said:
If it were mine, I would have it ground to the proper contour at your local machine shop. There should be several in Calgary that can to the work.

If you're extremely handy and extremely careful, you could use a very fine file and stone to profile it properly yourself. Very tedious and if you aren't comfortable with it, don't attempt it.

There are some good smiths in Calgary that could do it for you as well.

You could also ship it to Bits of Pieces, they can do the job, but I've heard they're extremely busy right now.
Click to expand...

I didn’t think most machine shops have the license to work on firearms. Also, if I machine the left side to match, I will need custom bases or shimming as well for height drop. I think that’s going to cost a lot so it’s not as attractive.
 
Techball said:
I didn’t think most machine shops have the license to work on firearms. Also, if I machine the left side to match, I will need custom bases or shimming as well for height drop. I think that’s going to cost a lot so it’s not as attractive.
Click to expand...

It's your call. I would rather shim a receiver that's level than just on side. To many ways for that to go wrong.

I picked up a Savage 110 at a gunshow, from a walk in. Same problem. About twenty minutes with a file and some clean up with 400 grit strip cloth and all was well. I didn't want to sell it to someone that way. Whether the fellow that sold it to me knew about it or not???
 
bearhunter said:
If it were mine, I would have it ground to the proper contour at your local machine shop. There should be several in Calgary that can to the work.
Click to expand...

Can you name any that possess the firearms business license that would allow them to gunsmith?

A couple of ways to fix this...

I suggest placing a small shim in the appropriate place with the screws barely tight... measure with a level and see if that set up is level enough for you... then take it apart and add epoxy, reassemble, check again and let cure with the screws barely tight. Release agaent on the action, none on the base. When cured dissemble and clean up. Then assemble with tight screws.... and lap the rings, all Talleys need that.

If your front ring lines up dead on to start with you can use that and a lapping bar to line up your rear ring and bed it with loose screws being lined up with the tight front ring...
 
Thank you GunTech. I think I will follow these instructions exactly. I will start working on this and provide updates.


guntech said:
Can you name any that possess the firearms business license that would allow them to gunsmith?

A couple of ways to fix this...

I suggest placing a small shim in the appropriate place with the screws barely tight... measure with a level and see if that set up is level enough for you... then take it apart and add epoxy, reassemble, check again and let cure with the screws barely tight. Release agaent on the action, none on the base. When cured dissemble and clean up. Then assemble with tight screws.... and lap the rings, all Talleys need that.

If your front ring lines up dead on to start with you can use that and a lapping bar to line up your rear ring and bed it with loose screws being lined up with the tight front ring...
Click to expand...
 
guntech said:
Can you name any that possess the firearms business license that would allow them to gunsmith?

A couple of ways to fix this...

I suggest placing a small shim in the appropriate place with the screws barely tight... measure with a level and see if that set up is level enough for you... then take it apart and add epoxy, reassemble, check again and let cure with the screws barely tight. Release agaent on the action, none on the base. When cured dissemble and clean up. Then assemble with tight screws.... and lap the rings, all Talleys need that.

If your front ring lines up dead on to start with you can use that and a lapping bar to line up your rear ring and bed it with loose screws being lined up with the tight front ring...
Click to expand...


Bits of Pieces.
 
Concluding post for this thread.

I bedded the base using JB weld to cement in a brass shim under the right side of the base. This levelled the base and elevated the rear base ever so slightly. Then I lapped the rings (which is how I know the rear is slightly higher). It’s done! Extra low extended Talley lightweight rings is the perfect cheek weld with a Leupold 40mm objective. Very low profile with the sporter barrel. Thanks for all the help! Especially Potashminer for reminding me to use masking tape to avoid messy cleanups!
 
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