Duke, this has been a very interesting read for sure! your efforts are not waisted! what you are doing is a learning curve! you have a rifle your trying to figure out how to make it work! but I think you have found the ugly side, and that is the barrel! The 350mag is not a gun to have barrel issues with, their hard enough to shoot accurately when all is working correctly, with a lot of practice! if I were you I would try to find another barrel, In my experience with the 350mag, the shorter the barrel the better off you are, due to the stroke length, the faster the pellet gets out of the barrel the less the chance of human error! with hold issues! just my thoughts!
I think most people shooting the 22 version are getting velocities like that in the AA rifles? High 500's?
Pretty much all magnum rifles have 19-20ish inch barrels.
Mark,I have played with the idea of chopping the barrel. The 350 Mag is a little too long, as far as cocking ergonomics and field handiness go, and the chop would fix these, even if accuracy benefits weren't to be had. The 350 is so easy to cock, that a moderate chop wouldn't hurt the cocking effort, either.One biggish chopping issue with my guns is that I need the front sight. So, chopping a barrel neccessitates making new dovetails for the front sight. Nothing some skillful work with a Dremel and diamond files + a little bluing liquid couldn't do, but still something of a challenge, getting everything absolutely centered and aligned. Now, the new .22 cal barrel is loose everywhere but the choke. In this case, chopping the choke (which would certainly go with any meaningful chop) might create a scatter gun. Premilinary shooting in tells me this barrel can be accurate with the big FTT's. Further testing pending...
There's always something, Grrr.Having accuracy issues with my 350 Mag I took the gun apart, yet again.I noticed the yoke under the receiver that the front stock screws go into (see pic) is loose: it can be rocked side to side for about 1mm total travel. It's obvious movement here can wreck accuracy, as the irons have a chance to move during the shot sequence, even when the stock (and the shooter) didn't. 1mm movement here projects out to several mm's at the muzzle, to maybe inches at the target...Let me wonder what Diana engineers were thinking, joining the yoke into the receiver by a SCREW, in a magnum springer known for its powerful recoil? Sure, the screw head has been struck (twice) by a punch at the factory, but it just cannot suffice to make the joint magnum-proof. There's a reason other manufacturers weld this joint. Unscrewing the yoke screw revealed a machine-oil soaked mating surface, lightly ribbed for extra friction. The yoke itself is dovetailed into the receiver bottom, and doesn't want to come off (not that I really tried, seeing no reason to risk it). I reckon cleaning, Loctiting etc., possibly re-punching are in order here, but let's hear if you have had the same issue and how you dealt with it.