I've had at least six 340 over the last 45 years. Mostly 22 Hornets and one 30-30. I've tried to buy three 225's over the years, but they are always priced like high grade Winchester Model 70's!
In talking to my buddies that own and load for them, 1) keep the FPS below 3000 with 50/55 grain bullets, 2) Flat based bullets respond best, 3) Brass prep: Primer Pocket, Flash Hole, Uniform Trim Length & Neck Wall Thickness are all critical.
My experience with that series of rifle is, they prefer Ball style powders, such as WW748 and H335.
The 223 and 22-250 get much better velocity, so stick to slower accuracy loading.
The Split Action causes problems with scope mounting. Most models were drilled and tapped for the two-piece Weaver side mount cantilever bases (with Weaver rings). The scope axis will be 3/4" to left of bore axis and the mount will handle objective Lense bells of 44mm or a little more. On my Hornets I zero at 150 yards Knowing 300 is the practical limit. (Many rifles are missing the rear sight because it interferes with scope mounting; I found mounting the rear sight backwards works fine out to 150-175 yards, with a 100 yard zero.)
Ivan