This is what I had on my 350
http://www.pyramydair.com/s/a/UTG_Scope_Mount_Base_Fits_RWS_Diana_34_36_38_45_Compensates_for_Droop_Stops_Scope_Shift/2298However, because of weight, I went to just a one piece mount. I did have to shim the scope to make it work, but it is holding fine so far. My Leapers AO scope was having some issues. It is now on the Whisper and they love each other!
I bought another non-AO scope Leapers Golden Image 3-9x40 Rifle Scope, Illuminated Mil-Dot Reticle, 1/4 MOA, 25mm Tube, Weaver Rings, Rubberized Exterior, and broke the mount on it with my screwdriver! I ordered a one piece mount with 30 mm rings (rubber makes the tube thicker), and it has worked great-no slipping nada.
Just my opinion, but you'll either need to shoot the B38 a lot, or get a lube tune at least. Miy 350 was brutal early on to shoot. The inside guts should look about the same as a 34 I would think making it not too hard to take apart.
Your new gun I think will be smoother. I know folks here disagree between the clones and the real thing, but the real thing tends to be smoother out of the box, is delightful to look at, and is just better made. That isn't to say you can't make the clones better because you can. (Not trying to start anything I'm just trying to make a point and I don't know how).
Congrats on the new gun! If you get to the end of your rope with the B28, I can always buy another gun rack and it can have a home in Tennnessee
