Unheard of: shimming?

BBq_Woa!

BBq_Woa!

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Hi there.

after much frustration with a particular scope, i troubleshooted by mounting it on 2 other rifles, to find that the scope body itself is slightly canted left,

i fixed the problem by shimming with cut slices of business card.
it's now perfectly zeroed and straight.

i'm happy it's done, but sure am surprised by what I had to do.

has anyone else ever shimmed a scope?
is it completely unheard of or a sort of normal thing to be needed every now and then?
-Derek
 
Not sure what you mean when you say that the scope body itself is alightly canted left. The scope itself is crooked, or the mount system holds the scope angled to the left?
The are mount systems with built in windage adjustment. Not unusual to use shims under the bases to alter elevation.
Some rings are designed with built in offset, so by reversing the rings, you can control windage to a certain extent.
Burris Signature rings incorporate eccentric bushings which allow a scope to be shifted in whatever manner is required. I usually use slips of beverage can aluminum to make shims.
One consideration in shimming is that if rings are not in alignment, the scope is being tweaked. This is why I prefer the Burris system.
 
Business cards are handy .. their long term stability if soaked are questionable .. I have used brass shim ... other folks find hard plastic cut from jar lids, packaging or other sources etc work well too.
 
I don't know whether it's the holes drilled in my savage's receiver, the 2 piece weaver bases, or the scope itself, but I need shimming to correct for windage. I have burris zee rings, and the rear ring has a +20, -20 combo to give me extra elevation, but the front ring has a +10,-10 combo rotated 90 degress so that the windage is centered when I'm sighted in. The whole thing shoots fine so I'm not worried about it.
 
From mounting several hundred scopes we find the two modern production firearms with the most inaccurate holes drilled in the receiver are the Savage bolt action centerfires and the Ruger 10/22. Both rifles seem to have the occasional receiver that has the four mounting holes drilled in a straight line but angled off to the right side. The mounts still fit but most scopes don't have enough internal adjustment to center the reticle on a boresighter and in many case not even enough adjustment to even get into the right side of the grid of my boresighter. A quick way to check is to place a straight edge (we use a metal yardstick) in line with the scope mounting holes on the receiver and compare the relationship with the end of the barrel at the muzzel. In many cases when the holes are drilled wrong (or occasionaly the barrel is not square to the action ) the edge of the straight edge is already off the outside edge of the barrel. We can correct this with an adjustable ring or base for windage in most cases. Phil.
 
I added about 40 MOA of cant to my pellet gun this way. I'm sure it'll be a huge mess once it gets wet, but so far it's holding together. I'm surprised it lasted this long!
 
Herb McBride used razor blades, if I recall correctly.


http://www.amazon.com/rifleman-went-war-Herbert-McBride/dp/B00086LXDE
 
Last edited:
AP said:
Business cards are handy .. their long term stability if soaked are questionable .. I have used brass shim ... other folks find hard plastic cut from jar lids, packaging or other sources etc work well too.
Click to expand...


I love the brass shim stock, you should be able to get an assortment at your nearest old school automotive supply shop or industrial supply shop.
 
I've shimmed a couple... you can actually by kits for it.

They come with several different colours of plastic strips ranging from 1/8th inch wide to 1 inch wide and any where from 1/32 thick to 1/8th inch think.

They work well.
 
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