OK - some results, for what it's worth. I loaded .30-30, spread from 6.0 to 10.0gr of TG, pushing that Lee 150gr FN gas checked, with Rem 9 1/2 Mag primers (what i had on hand). Without a chronograph, I can say the 6.0 load recoiled just a touch more than a .22, and from 8.0 thru 10.0 grains, recoil increased pretty quick. No excessive pressure signs what-so-ever, at any loading.
I made sure to try several powder positions, from muzzle down, to muzzle up, then level & tapping the frame to level the powder, and noticed no difference in ignition or report. All groups hovered about 1" @ 25 yards with iron sights, but of course, the groups were low compared to start loads with jacketed bullets & typical powders (4064, 4198).
I won't hesitate to load the 6.0gr of TG, & omit the gas checks, for close range plinking or small game loads.
I also loaded some 7.5x55 Swiss for my K31, with 23.0 & 24.0gr of IMR 4198, and the same Lee 150gr FN gas checked. Both loads grouped about 1" at 50yds, and had about 1/2 the recoil of GP or Privi ammo. More testing to come on this.
Most notably, I see ZERO leading in both rifles, and, strangely, the bores seem to look better after firing cast. (?)