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Shims - LOP - POI


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This is a recurring question.


Part of the confusion comes from the fact that the Benelli manual doesn't do a good enough job of explaining how drop at heel correlates to POI (point of impact).


Firstly, you have to understand how shotgun sighting works.

There is no fixed rear sight on a shotgun. The shooter's eye works as the rear sight.

Changing the eye position is the equivalent of moving the rear sight on a rifle.

This is why it's important to consistently use the same stock position and cheek weld when shooting a shotgun.


Raising the head off the stock raises the rear sight. That means that the POI will go up.

Moving the head left means the POI goes further left.


In this graphic, I have combined the Benelli drop change chart with a very good explanation of drop at heel relates to POI.

The full discussion can viewed here http://www.trapshooters.com/cfpages/thread.cfm?Threadid=246131&ShowDeleted=Yes&SortBy=ASC




One can go beyond the stock settings with a raised comb (higher POI) or longer/shorter recoil pad.



With regards to Right and Left adjustment, you only have two choices with the Benelli, unless you have a custom locking plate made for you.

The SX plate, which provides a "cast-on" condition, meaning that the stock is moved slightly left to allow for the shooter's cheek thickness (offset from center) and attempts to center the eye over the receiver for left-handed shooters.


The DX plate provides the opposite condition for right-handed shooters.


So, what can you do at this point?

Well, the first thing you should do is to make sure that you are using proper form. The only way to do that is to have a knowledgeable shooter or gunsmith evaluate your shooting form and offer pointers accordingly.


If you think you have proper form, and you just want to get the gun shooting where you aim, then you'll need to customize the shotgun beyond the capacity of the stock shims and plates.


As mentioned previously, a higher comb could help you with raising the POI.

You could also benefit from the optional thicker recoil pad. That would push your cheek further back on the stock and elevate your eye, raising POI.


If you want more cast-on or cast-off, which would move the POI right or left, then you could take one of those plates to a machinist and explain that you need more offset than the stock plate allows. He could fill the existing hole and drill a new one further from center. Be careful with how far you go. You are probably real close and a 1/4" may be all you need.

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Tucker. I am not the sharpest knife in the drawer, and I will admit that. I also will admit that you've forgot more about Benelli's than I know. I may be wrong here, but it looks to me like, on your chart, that the thicker shim © will make the gun shoot to a higher POI. Am I reading it wrong? Mike

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The Z shim gives you a drop at heel of about 50mm.

The C shim increases the drop at heel value to about 65mm.


Now look at what is stated in the graphic about how more drop at heel rolls the head back and thus elevates the shooter's eye.

That results in a higher POI (or lower POA).


This graphic shows what the various measurements are and how they relate to each other.




Wording can confusing and misleading, if not clarified.

For example, Stoffer wrote, "if you lower drop you will also lower point of impact".


Did he mean "lower drop" as in increase the amount of drop?


Or did he mean lower drop as in decrease the amount of drop?


One way he's right and the other he's wrong. :confused:


It's like the old joke about the guy at the nuclear power plant.

His supervisor had to step away for five minutes, but he told the worker before he left, "The pressure can't go too high."

Edited by tucker301
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I know what your saying, Tucker. It can be confusing..However it gets worded, the thicker shim allows me to see the whole rib, rather than just the forward half, which in turn, lowers my POI. The manual is a little vague in that area..Thanks for posting the information. Looking forward to seeing your waterfowl pictures soon..Mike

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Sorry, I still have to disagree, the following link maybe proves me right?



Best regards Stoffer


Here is where the author caught himself getting close to figuring things out, but then he gave up.


Just to see if there was any difference, I fired another five shots with the 50 mm shim at a new patterning paper, but using a different load. That load patterned only 15 inches high instead of 20 as with the previous load,
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I still dont get it! If you increase drop from 50 to 65mm POI will be lower! But your chart shows that the opposit is the case!:)



I have to agree with Stoffer. That's what it looks like to me. The chart shows that a thicker shim will raise the POI, when in fact, it lowers it. Mike

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