H1000 and 4350 will both work with your 180s.
If you are in a crunch for time, I would at least load 4 at 2 grns before max listed, and 4 at max listed loads. Check for pressure signs on the 1st charge before trying the second. If one particular load gives you the velocity and accuracy you are after, load a batch, shoot a group to verify consistency, zero the rig, and go kill and elk. There are much better ways to come up with your loads, but that method works when time is a concern.
Look on Hodgdon's site for data. I don't have mine with me and can't remember what weights I used for the two.
I usually grab for H4831, IMR7828, or R22 for the 300WM and 180s, but I have used the two you mentioned and they work well too.
There are quite a few good powders for pushing 180s in the 300WM.
Good Luck
loder
