Greetings Again kiwi-adam,
Have been thinking of your predicament holed up in Lower Gotham City waiting for opening up and had a few thoughts that may help.
As I said previously I would not be in any desperate hurry to get on to load development. Rifles usually take a number of rounds to smooth up and settle down. For your rifle I suspect that accuracy will be good to start with and better as it beds in. You said in your OP that the primary use for the rifle is hunting out to 400 metres. This does not require .25 minute accuracy so your current need is for a load that duplicates your factory loads. As suggested earlier zeroing the rifle and conserving your remaining factory loads for hunting. I looked at some of the loading data and it seems pretty consistent so coming up with a factory duplication load should not be that difficult. Please chronograph your factory loads as part of your zeroing process but I suspect that they will give a little under 3,000 feet per second. I will do some more notes tomorrow but in the mean time I would work on doing your load development yourself once all of your cases have been fire formed and conditions improve. No point letting someone else have all the fun at your expense.
Regards Grandpamac
Bookmarks