most everyone familiar with the k-31 in 7.5x55 knows it shoots a .307 bullet, but since the american made .308 is all we can get it works perfectly in place of the .307. The highest velocity info that I have found is 2839fps in front of 51.0 grns of H4350 using a 125 grn bullet. A .308 win. shooting a 125grn bullet is capable of 3194fps using 48.0grns of imr 3031. Since the case of the 7.5x55 is slightly taller than the .308, In my custom action, I should be able to load up to and possibly over the .308's fps. I would not recommend trying this using any of the k-31's. H4350 or 4320 will most likely be my first choice of powders that I try.
I used the stiller TAC300 custom action which uses the standard bolt face for the .473 range of cases, then had it opened up to accomadate the 7.5x55 case.

the barrel is a Hart stainless in .308 bore then chambered to 7.5x55. $315
chamber reamer from Pacific Tool and Gauge $129
stock is from Stocky's Stocks in Florida $197
Timmney trigger and Vias muzzel brake
$200 from Brownells
scope is Leupold 6.5x20-50mm

will send pics of target and field report when avaliable.
Main purpose........ No one else has one like it!!!!!!!!!!!!!