So far mine has been fairly accurate with crossman premier which I view as a crummy pellet. The gun came with 5-6 guns of various pellets one being the Brazilian made RIFLE round pellet. The previous owner stated it was the most accurate he had tried. I tried some out and it was very accurate. Just not many left.
This may help with the shimming. lay two pencils down in parallel and as you move one end of the top (scope) pencil you can see the effect of the bottom (rifle bore) pencil.
In most cases you're right. Some cases it is noticeable. The Diana's can be pretty bad. Looking at the rifle from the side makes the bend least noticeable. Looking down the top or the side of the gun makes discrepancies more obvious. These are clearly noticeable unless your Mr. Magoo
Wow, that looks like it was run over by a truck. Since you work on Dianas do have any experience bending the barrel on a 48? I want to bend mine but not sure about that barrel harmonic crap they put in there under the barrel sleeve. I guess they are brazed on, so not sure if it is feasible.
The barrels aren't bent from the factory. They just point ever so slightly downward. Even a small angle like 1° downward will move your pellet impact 15" at 25yds. I'd imagine getting the perfect lockup position is probably fairly difficult to do even for professionals.
I'm sorry, I was referencing Dianas well known and deserved reputation of drooping barrels. I don't really work on Dianas. I only did one old D27 for a friend and that's it. I don't know them well enough to comfortably work on them for people. Sorry I can't help you.
