LOP & Drop

[rdsdccp]

I have 12 ga shotgun and I want to change the LOP and Drop on the gun. I have the owners manual with the exploded view of all parts.
I am mechanicaly inclined. I want to add one spacer for the LOP and the 50 spacer for the drop. Anyone have any advice or tips on doing this? My understanding is the 50 spacer is used to raise the muzzle end which is what I need to do. Thanks for reading.

 

[stubblejumper]

Without knowing what a "50" spacer is, and which shotgun you are referring to, we can't be of any assistance.

 

[G_Alan]

More info on the model would help. But if it's a 2 piece shim make sure the spacers are both index properly together.

 

[rdsdccp]

The shotgun is Weatherby Element semi. The LOP spacer is a one piece, hard plastic labled 5mm. The others shims are for cast and drop. The 50 & 55 are to raise and the 65 is to lower the drop. The cast shim can flipped according to right or left cast. So the manual says. I guess I would remove two screws in the butt end, install the shims as I need and reassemble. What I am wondering is, how do you line up the two screws in the butt end? By feel? By sight? Am I over thinking this? Thanks

 

[struff55]

follow the instructions that come with the firearm likely better than asking the blind for advice

 

[Ol' Flinter]

Changing the position of your eye relative to the muzzle is analogous to changing the rear site on a rifle. Raising your face on the comb will effectively raise the point of impact of your shot charge. If you "raise the muzzle end", you will raise the point of impact: is that what you want to do? If so, then raise your comb and corresponding eye position. If you want to approximate the change required, you can measure the distance from your eye to the muzzle when the gun is mounted and then simple geometry will tell you how much to raise or lower the comb to achieve the change in point of impact you wish to achieve. As a simple example, if the distance from your eye to the muzzle is 1 yard/36" and you want to raise your point of impact 12" at 40 yards/1440", then you have to raise the comb 36 x 12/1440 = 0.3 " at the point where your face meets the stock, which typically is 7 to 7.5 inches ahead of the butt plate.
Increasing the LOP can also have a very small effect because your face will be further back on the stock and therefore a bit lower if it is a typical butt stock with more drop at heel than comb but usually that change downward is only a very small fraction of an inch and not problematic with a field gun... potentially more so with a gun being used for long yardage handicap trap.
I hope that helps.

 

[rdsdccp]

Changing the position of your eye relative to the muzzle is analogous to changing the rear site on a rifle. Raising your face on the comb will effectively raise the point of impact of your shot charge. If you "raise the muzzle end", you will raise the point of impact: is that what you want to do? If so, then raise your comb and corresponding eye position. If you want to approximate the change required, you can measure the distance from your eye to the muzzle when the gun is mounted and then simple geometry will tell you how much to raise or lower the comb to achieve the change in point of impact you wish to achieve. As a simple example, if the distance from your eye to the muzzle is 1 yard/36" and you want to raise your point of impact 12" at 40 yards/1440", then you have to raise the comb 36 x 12/1440 = 0.3 " at the point where your face meets the stock, which typically is 7 to 7.5 inches ahead of the butt plate.
Increasing the LOP can also have a very small effect because your face will be further back on the stock and therefore a bit lower if it is a typical butt stock with more drop at heel than comb but usually that change downward is only a very small fraction of an inch and not problematic with a field gun... potentially more so with a gun being used for long yardage handicap trap.
I hope that helps.

Thanks for the reply. Before I reach for the screwdriver, I should do some measurements first.

 

[cosmic]

The two buttstock screws fit into holes in the buttpad. In turn, they line up with threaded holes in the buttstock. Seat the screws fully in the buttpad, thread into the buttstock holes, working back and forth. Pretty hard to mess up. I assume they are long enough to accommodate the LOP spacers.
Shoulder the gun with your eyes closed. Open your eyes, note what you see looking down the barrel. Are your eyes on center with the rib? How much of the rib do you see? Repeat several times... Adjust cast and drop accordingly, until your eyes are centered on the rib, and you see roughly a bead height of rib.