VV N310, N320 will work for you and you will find the load between 10 and 5 grains.
BUT
- you might have unrealistic expectations to the terminal effects on the bullet of choice
- you cannot mix'n'match supers and subs and expect to hit something (with the subs)
- you probably cannot shoot the subs w/o certain preparation and expect to hit something
- velocity variation would be out of window (bore condition, successive round count etc)
- at 50m/y it's kind of difficult to make a load that WOULD NOT have acceptable accuracy (velocity wise)
- at 150y it's VERY difficult to make a load that WOULD have acceptable accuracy (velocity and general dispersion)
- even if you succeed in everything else, 308 subs have practically the same trajectory as 22LR subs so over 100y/m your basically "centimeter per yard" drop if not worse
If you insist on trying, first get hold of reliable chrono. Then work down as stated, you can surely find loads from US forums. If you're not bothered to find them, DO NOT bother with loading them.
Make sure to have reasonable samples and pay attention how velocity varies (prob rises) when round count goes up in single session. Try to find cleaning regime that gives you decent amount of shots with decent variation, shot as you would in real use case (so no consecutive shots w/o long cooling periods in testing). Then zero with cold bore, preferably over several sessions. Similar support as using in field.
Make very sure you start field testing with short distance (50y in your case) and bait station or similar where you take the guesswork out of equation. I'd bet Sub-X is OK for 50y terminal wise. Longer ranges it's a toss. Also make sure you practice religiously and make sure you have foolproof way of getting ranges. Work very slowly from 50y out to the distance you feel comfortable. Remember that even 50y the flight time is relevant, fox might move after you make the decision to shoot and before bullet gets there.
