Shimming one piece base.

[kawicrash]

Hello.
I was setting up my new to me Howa 1500 mini that came with 0 MOA Warne one piece base.
I had a set of Burris Z rings so I figured I'd use them as they are reasonably decent.
Scope is a new Bushnell Prime 4-12x40. Inexpensive, but not bad for the price. On sale at Cabela's and a $40 Bushnell rebate.
Anyway, I set the turrets in the middle and did the eyeball bore sighting. Windage was good, but the crosshairs were about 3 feet above my point of aim through the bore.
I could crank enough to get it on, but it used up essentially all my elevation.
I have shimmed two piece bases before, but never a one piece. Any issue with shimming the back of the base? The scope still slides on the rail nicely, so it doesn't appear to be warping it or anything. I used a piece of pop can folded in half as my shim between the screw holes.
Any risk of stressing the scope? As I said, I left the rings on the scope and can easily slide it all the way front to back, and it's just a tiny bit, so it doesn't seem to be warping anything.
Just looking for some input. Better place to put the shim?
Any risk of bending the scope? I do remember reading something about this being an issue on Howa's??
Any ideas welcome, thanks.

 

[dan belisle]

Switch your rings for Burris Signature rings and use the inserts to compensate for your elevation would be my first choice. - dan

 

[guntech]

I have shimmed a few.. I prefer to bed the shim and base at the same time... clean the bass, release agent on the action and screws... place the bedding compound and only light pressure on the screws just enough to line the base up... after the epoxy has cured remove and clean up excess and drill out the slightly plugged screw holes, then install tight.

 

[Potashminer]

Hello.
I was setting up my new to me Howa 1500 mini that came with 0 MOA Warne one piece base.
I had a set of Burris Z rings so I figured I'd use them as they are reasonably decent.
Scope is a new Bushnell Prime 4-12x40. Inexpensive, but not bad for the price. On sale at Cabela's and a $40 Bushnell rebate.
Anyway, I set the turrets in the middle and did the eyeball bore sighting. Windage was good, but the crosshairs were about 3 feet above my point of aim through the bore.
I could crank enough to get it on, but it used up essentially all my elevation.
I have shimmed two piece bases before, but never a one piece. Any issue with shimming the back of the base? The scope still slides on the rail nicely, so it doesn't appear to be warping it or anything. I used a piece of pop can folded in half as my shim between the screw holes.
Any risk of stressing the scope? As I said, I left the rings on the scope and can easily slide it all the way front to back, and it's just a tiny bit, so it doesn't seem to be warping anything.
Just looking for some input. Better place to put the shim?
Any risk of bending the scope? I do remember reading something about this being an issue on Howa's??
Any ideas welcome, thanks.

Think about that one piece base - if you want to keep it dead flat on top and raise the rear, than only the very tip of front can also touch - so actually need tapering shim or bedding right from front tip of base to the rear. Or, I suppose, a thin shim between front two screws and a thicker shim between rear two screws with air gap for the rest of the way in front of and behind each pair of screws??

I found it very handy to use a lapping bar - so install bases - fuss to get their tops as dead flat to each other as I can. No doubt similar with one piece - when screws torqued down, that one piece can become banana shaped or twisted. Install rings - snug up cross screws - removed tops - use lapping bar to see what gets touched. If a ring is "tipped" or tilted or "askew" to the other, you see that right away as just a thin sliver of finish being removed from the high edge. That, I think, is what bends scopes - that the rings are not concentric to each other - so use a lapping bar to satisfy that the scope bears squarely and fully into each ring's bottom part.