Question

[steve_b_wales]

Does adding a shim on the rear scope mount allow more reticule movement up or down?

[scarecrow243]

it can but if its an air rifle it would be better to use fully adjustable mounts that way you leave the scope at the centre clicks and use the mounts to zero

[Mr.C]

down, however I would recommend adjustable mounts if you can.

I have a set of 1" mounts form sportsmatch I could part with or Burris XTR signature rings will sort you out with 30mm tube.

 

Just now, Mr.C said:

down, however I would recommend adjustable mounts if you can. So adds MOA 

I have a set of 1" mounts form sportsmatch I could part with or Burris XTR signature rings will sort you out with 30mm tube.

 

 

3 minutes ago, Mr.C said:

 

 

 

double post

[old'un]

This obviously relates to a question I asked you earlier about putting shim under the rear mount.

This is how I see it…..if you were to clamp the rifle in a vice and line the cross-hairs up with bullseye at say 30 yards, if you then put shim under the rear mount, thus lowering the cross-hairs from bullseye, you would then need to raise the rifle to bring it back on bullseye, this will surely make the rifle shoot high as you have fiscally moved the reticule down by adding shim to the rear mount.

I stand to-be corrected by those with more knowledge than me of rifles and scopes.

 

 

Edited May 28, 2024 by old'un

[scarecrow243]

some rifles  scope rail with digital scopes this makes the cross hair very low on the screen so too compensate fully adjustable mounts or shimming is needed too bring the cross hair back to a centre position thus allowing more scope reticule travel

[old'un]

Just now, scarecrow243 said:

some rifles  scope rail with digital scopes this makes the cross hair very low on the screen so too compensate fully adjustable mounts or shimming is needed too bring the cross hair back to a centre position thus allowing more scope reticule travel

So does shiming the rear mount make it shoot higher or lower?

See this thread...https://forums.pigeonwatch.co.uk/forums/topic/446250-mtc-copperhead-f2-scope/

Edited May 28, 2024 by old'un

[scarecrow243]

no its only to centralise the cross hairs  every rifle points upwards when using a scope or open sights

[oldypigeonpopper]

Hello, The only time i shimmed a scope is with a Photon XT on a CZ 455 but this was a well known problem , have never needed to shim a day scope, seems only night vision but i maybe wrong if people need to shim a day scope, it also depend on the type of rifle and rail, saying this i bought a cheap night scope off Aliexpress,  Megorei M 5 and that needs adjustable mounts, saying this it makes a good cheap night spotter with a fitted handle as you can turn off the reticule, 

Edited May 28, 2024 by oldypigeonpopper

[eggy74]

If you exaggerate the scenario the scope will be pointing downhill by shimming under the rear mount, so the cross hairs will appear lower than before and need to be raised to meet the poi. if you dont raise the crosshairs the rifle will appear to shoot higher for the same given distance 

 

[old'un]

25 minutes ago, eggy74 said:

If you exaggerate the scenario the scope will be pointing downhill by shimming under the rear mount, so the cross hairs will appear lower than before and need to be raised to meet the poi. if you dont raise the crosshairs the rifle will appear to shoot higher for the same given distance 

 

That's what I thought.

[scarecrow243]

some air rifles with a scope that has small turrets need shimmed as there is not enough clicks

[old'un]

12 minutes ago, scarecrow243 said:

some air rifles with a scope that has small turrets need shimmed as there is not enough clicks

I can understand that but we are talking about shiming the rear mount of a scope and the effects it as.

The rifle is a .22LR and scope MTC Copperhead F2 scope, see link above.

 

[scarecrow243]

Hi i looked at the above link he needs fully adjustable picatinny mounts  so he can tilt the scope too the impact point after returning the turrets to centre

[Mr.C]

Agree with @scarecrow243. Centre the scope , mount it on adjustable mounts ,then adjust to your chosen zero.

Shimming is a very good way to bend a scope unless you're careful.

[oldypigeonpopper]

Hello, i do not see any problem with Shimming a day scope, if it is shooting high or low by a small margin and you run out of adjustment it can be shimmed, my way to check is central the cross hair, shoot at a target say 20 yards , see where pellet hit and shim accordingly 

[Fil]

3 hours ago, old'un said:

So does shiming the rear mount make it shoot higher or lower?

See this thread...https://forums.pigeonwatch.co.uk/forums/topic/446250-mtc-copperhead-f2-scope/

Shimming the rear makes it shoot higher. Think about it. You have the reticle on the "bull" then you raise the rear. The reticle sights lower. Then what do you have to do to get reticle on bull again? raise the muzzle. I've done loads. 

[London Best]

I’ve fitted dozens of scopes over the years but have never ever come across this problem.

[old'un]

42 minutes ago, Fil said:

Shimming the rear makes it shoot higher. Think about it. You have the reticle on the "bull" then you raise the rear. The reticle sights lower. Then what do you have to do to get reticle on bull again? raise the muzzle. I've done loads. 

Yes that's what I said in an earlier post above.

[wymberley]

Where am I going wrong? 

The front and back portions of the scope tube run in line with each other. If you stand the bottom halves of two (half decent) ring/mounts of the appropriate size on a flat surface and lay a scope on them with both tube portions in contact with the rings the tubes will be in contact with the rings along their (rings) whole length. If you now lay the top half of the rings on top of the bottom ones, then the same will apply. Let's assume that our scope is a Hawke and we then screw the two halves of the rings together and apply a loading of 16 in/lbs. Nothing will move and the scope will be secure in its 'housing' with no abnormal/detrimental load applied. All being well this assembly will fit nicely on a rifle rail when torqued to 30 in/lbs with again no abnormal loading. However, it turns out that something is not right as the rifle/scope combination will not zero and the adjustment has bottomed out. OK, we'll either shim under the foot of the rear mount or pack the lower half of the ring to raise it thus, hopefully, correcting the problem.

But we haven't we've simply treated the symptom and not the defect and in so doing have applied a bending motion to the scope which it was not designed for.

[old'un]

Just now, wymberley said:

Where am I going wrong? 

The front and back portions of the scope tube run in line with each other. If you stand the bottom halves of two (half decent) ring/mounts of the appropriate size on a flat surface and lay a scope on them with both tube portions in contact with the rings the tubes will be in contact with the rings along their (rings) whole length. If you now lay the top half of the rings on top of the bottom ones, then the same will apply. Let's assume that our scope is a Hawke and we then screw the two halves of the rings together and apply a loading of 16 in/lbs. Nothing will move and the scope will be secure in its 'housing' with no abnormal/detrimental load applied. All being well this assembly will fit nicely on a rifle rail when torqued to 30 in/lbs with again no abnormal loading. However, it turns out that something is not right as the rifle/scope combination will not zero and the adjustment has bottomed out. OK, we'll either shim under the foot of the rear mount or pack the lower half of the ring to raise it thus, hopefully, correcting the problem.

But we haven't we've simply treated the symptom and not the defect and in so doing have applied a bending motion to the scope which it was not designed for.

That is true and also the scope and bore are now not parallel.

[Fil]

21 hours ago, old'un said:

Yes that's what I said in an earlier post above.

Ah sorry, Didn't see it

Edited May 29, 2024 by Fil
shpelling

[Ultrastu]

Hawke do  plastic shims that sit in your mounts one front one rear .they are designed to not bend your scope if you set them at the correct distance apart .think they add 1 moa of elevation to point of impact  if big one is at the rear  low at the front . Designed  to solve this problem .

The usual problem is scopes run-out of vertical adjustment where the point of pellet impact is too low at chosen zero and the scope won't adjust low enough to bring the point of impact up .shimming the rear mount allows you to effectively bring the point of impact up onto the cross hairs .

Hope this helps .

Edited May 29, 2024 by Ultrastu

[old'un]

13 hours ago, Ultrastu said:

Hawke do  plastic shims that sit in your mounts one front one rear .they are designed to not bend your scope if you set them at the correct distance apart .think they add 1 moa of elevation to point of impact  if big one is at the rear  low at the front . Designed  to solve this problem .

The usual problem is scopes run-out of vertical adjustment where the point of pellet impact is too low at chosen zero and the scope won't adjust low enough to bring the point of impact up .shimming the rear mount allows you to effectively bring the point of impact up onto the cross hairs .

Hope this helps .

The problem Steve’s having is the rifle is shooting way too high.

[Ultrastu]

OK. The reverse may apply then .Big shim at the front low and the back .