resting your gun on its buddybottle. loss of accuracy?

I find that the accuracy when shoot off a bag is related to how far forward or back on stock you rest the gun on the bag. I'm pretty sure it has to do with the harmonics of the vibration from the shot. You can experience this by taking a butter knife or other longish, thin metal object. Hold it between your thumb and index finger with one hand and flick it with the finger of the other hand or tap it on a hard object. The metal object will vibrate or not, depending on where you are holding it with your thumb and index finger. Move your holding spot up and down the object until, when you flick it, it vibrates. This point is where the vibrations moving up and down the object in a sort of infinity loop cross. It teds to be about 1/4 to 1/3 the distance of the object from either end point. I'm pretty sure this hold true for the rifle and why accuracy is affected by how far forward or back on the rifle you rest it on the bag. My experiments have shown that resting the rifle farther back towards the action produces better results. But, that may just be for my rifles. I suggest you experiment with this as my experience has shown there can be quite a difference in accuracy from just a few inches forward or back. 
 
"chasdicapua"I find that the accuracy when shoot off a bag is related to how far forward or back on stock you rest the gun on the bag. I'm pretty sure it has to do with the harmonics of the vibration from the shot. You can experience this by taking a butter knife or other longish, thin metal object. Hold it between your thumb and index finger with one hand and flick it with the finger of the other hand or tap it on a hard object. The metal object will vibrate or not, depending on where you are holding it with your thumb and index finger. Move your holding spot up and down the object until, when you flick it, it vibrates. This point is where the vibrations moving up and down the object in a sort of infinity loop cross. It teds to be about 1/4 to 1/3 the distance of the object from either end point. I'm pretty sure this hold true for the rifle and why accuracy is affected by how far forward or back on the rifle you rest it on the bag. My experiments have shown that resting the rifle farther back towards the action produces better results. But, that may just be for my rifles. I suggest you experiment with this as my experience has shown there can be quite a difference in accuracy from just a few inches forward or back.
I have experienced various effects like that too although it varies by gun. Some are far more hold sensative than others and some are more effected by what you rest them on and where on the gun you rest.

I don't use many bottle guns but the issue is the same with tube guns. Depending on how robust the breach and stock is, upward pressure towards the end of the tube or bottle can stress the threads where they connect to the action. 

One of the reasons I started getting interested in making my own stocks was the poi shifts I was seeing from relatively minor things like holding too hard or slightly over torquing a stock screw. It really doesn't take much.

I think that if you were building a rig for ultimate accuracy, you would free-float the bottle or tube and either rest on a separate piece (like how the bipod rail is on the metal trigger block on the Impact) or have a super rigid stock with as much of the bottle or cylinder free-floated as possible.

I have been wondering if the larger one-piece breach block on the Daystate Wolverine reduces this effect. I'm still not sure I would choose to rest on the bottle though. 

On some of the custom benchrest stocks I have seen for bottle guns, the bottle is protected by a wide extended forearm. I assume this is to give you something to rest on without putting pressure on the bottle.