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HELP! Which shim to change to to raise point of impact?


thefish

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I have a M1 Super 90 and I think it is the best gun in the Unverse. I use it for everything. Recently, I started using it for trap and am finding that it impacts low relative to where I aim. Thus to smack a clay, I have to raise the barrel and obscure the clay with the barrel to hit it. The problem doing this is obvious: once it disappears under the barrel, one cannot tell how far below the barrel the clay is.

 

The gun still has the original shims. In the kit, I have an "A" and "B" shim. Which should I switch to? Do I need to also change to the corresponding plates?

 

Thanks in advance,

TF

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i would probably go with the b shim since the c shim is installed and from looking at YOUR manual ya would also use the corresponding locking plate and it only takes a few minutes to swap out! i would not go with the a shim till i tried the b!! Follow directions and ya gotter whipped!! shooting behind clays is the usual problem for me anyways!!

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Thanks for your answer, it is truly appreciated. I'm still confused as to not how to do it, but why.

 

If I switch from the existing "C" shim, which according to the manual is rated with a drop of 63.5mm to the "B" shim with a rated drop of 59mm, I am thus decreasing the drop, i.e., raising the height by 4.5mm. Since the effective height will be raised by that much, won't this force the point of impact to be even higher?

 

It functions like the rear sights on a rifle, doesn't it? If you raise the rear sight, the bullet will strike at a higher point. Since it is already hitting too high (that is why I must lower the barrel to hit the clay), won't switching to a "B" shim make it even worse, or do I have it completely backwards?

 

Definitely a confusing topic with poor documentation/explanation in the manual.

Thanks again for your help.

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Thanks for your answer, it is truly appreciated. I'm still confused as to not how to do it, but why.

 

If I switch from the existing "C" shim, which according to the manual is rated with a drop of 63.5mm to the "B" shim with a rated drop of 59mm, I am thus decreasing the drop, i.e., raising the height by 4.5mm. Since the effective height will be raised by that much, won't this force the point of impact to be even higher?

 

It functions like the rear sights on a rifle, doesn't it? If you raise the rear sight, the bullet will strike at a higher point. Since it is already hitting too high (that is why I must lower the barrel to hit the clay), won't switching to a "B" shim make it even worse, or do I have it completely backwards?

 

Definitely a confusing topic with poor documentation/explanation in the manual.

Thanks again for your help.

 

it is easily confusing and to make it easier i hope this does not confuse us anymore but if your POI is high lower stock, if POI is low raise the stock ,now look in your manual and see which will raise your POI cause your gun is shooting low!!63.5 is lower than 59 and thats the way ya wanta go to raise the stock just like manual says "B" shim which a lower downward adjustment!! poi high lower stock , poi low raise stock , whats hard about that!! it just says it in an awkward way in manual but you want your stock to go UP if you are shooting low!!

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Yeah, he's right. You might have a D shim and plate in your gun however. They come from the factory w/ D or C shims and plates. You will be able to tell once you take it off. You need a 13mm deep drive socket w/ an extension to take off yor stock after you take off your pad. Stick your phillips screwdriver in vaseline to unscrew your pad so you don't enlarge you hole in the pad or rip it. Good luck dude.

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Oh, and get yourself a big piece of cardboard and step back 25 yards with a mod. choke and mount your shotgun from a gun down position and fire at an orange dot or whatever about 10 times and you will see exactly where you a 'Patterning". If low and a C shim and plate go to a B. Too high? Go to a D. Essentially, If you move the stock up or raise it the pattern goes up. Move the stock down or lower it ,pattern goes down. Move the stock right by inletting or bending the pattern will go right. Whichever way you move the stock is the direction you will move the pattern. Sorry for the monologue for those of you that know.

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Oh, and get yourself a big piece of cardboard and step back 25 yards with a mod. choke and mount your shotgun from a gun down position and fire at an orange dot or whatever about 10 times and you will see exactly where you a 'Patterning". If low and a C shim and plate go to a B. Too high? Go to a D. Essentially, If you move the stock up or raise it the pattern goes up. Move the stock down or lower it ,pattern goes down. Move the stock right by inletting or bending the pattern will go right. Whichever way you move the stock is the direction you will move the pattern. Sorry for the monologue for those of you that know.

 

Bingo :)

 

This person obviously has done the field work and is 110% correct based on what I have experienced from real testing over the past 18 years of shooting Benellis and working with shims.

 

I don't give a rat's arse what anyone says about POI not changing with shims changes. It does. Period.

 

I'm not talking about scopes, red dots, lasers, etc. I'm talking about just the factory beads.

 

We had this whole discussion last year. The naysayers driveled on for a bit and then disappeared as usual.

 

Just like Johnny, I can make my patterns go up and down like clockwork.

 

Good replies guys. It's nice to see posts from guys who actually shoot the guns being discussed :D

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Great answers, guys. Thanks. I'm going to try a pattern and see where it is most dense relative to the point of aim. Then, make an informed decision on shim choice.

 

A related question, though...in truth, on this particular gun, when you replace shims and change the angle that the stock is relative to the receiver, you are not changing the "drop at comb" in the classical sense, are you?

 

Anybody have any thoughts on why Benelli doesn't make all this a bit more clear? Have they published somewhere a guide on all this for the novitiate?

 

Thanks again for all the help.

TF

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