I dont know how much I can help with the 175g SMKs, as I shoot exclusively 168SMK and use Varget in my 308. That said, the Sierra reloading book (my favorite) is a little on the conservative side, if thats the book your using. But you did find two loads that didn't shoot to bad, and I dont know much about your rifle, like the barrel, light or heavy, if its a hunting barrel, dont expect to small of a group, anything under 1' would be good.
Also having access to a crony would be nice, but load development is the only time I use mine.
But having a little more info will help guys, in helping you with this load, hunting, or target at what distance, type of barrel, twist Etc.
I have R-15 but have never loaded with it, yet, Varget just works to good. I can give you my two best 308 loads, and info if it will help, you might look the 168 up in the book and get some idea, but your plan is not a bad one. But if you plan to use the magazine, you wont be able to move the bullet out much, and dont think you have to have a bullet jam, some 308s like a jump, mine love a .100 jump, and shoots in the .2s and .3s for 5 @ 100. Even with Fed GMM ammo. Or the two loads listed below.

24" 1 in 12" heavy varmint, after market barrel.
168g SMK 44.0g Varget COL 2.810 = 2655 fps
168g SMK 44.5g Varget COL 2.810 = 2701 fps
Good luck.
Mike.