In the early 1980's or there about a I spent a lot of time on a 660 Or 600 Remington. I replaced the stock with Kevlar, bottom metal with AL, barrel with high dollar 22". I worked on many loads. I worked on loads through April 2005. I thought that I'd share the loads. I didn't have a chronograph at the time.
55 gr H4895 Hornady Interlock 250 gr sp .7 MOA
55 gr Win 748 Hornady Interlock 250 gr sp .9 MOA
60 gr Win 748 Hawk 225 gr TOO HOT 7 MOA do not use
57 gr Win 748 Hawk 225 gr 5+ MOA
56 gr old lot IMR4064 225 gr Hawk 4 MOA
57 gr Win 748 250 gr Speer sp 1.9" MOA probably too high pressure
61.5 gr Win 748 225 gr Nosler PT 3.1 MOA probably too high pressure
56 gr IMR4320 250 gr Speer sp 1.5 MOA
55.5 gr IMR4064 250 gr Horn sp 1.4 MOA
57 gr Win 748 250 gr Horn sp .75" MOA top load - do not increase
53 gr IMR 4895 250 gr sp 1.8" MOA
60gr IMR4895 225 Nosler pt 2.8 MOA
56 gr H335 250 gr Speer sp 3.75 MOA
56 gr IMR4320 225 Hawk 5+ MOA
55.5 gr IMR 4064 225 gr Hawk 2.35 MOA
54 gr H335 250 gr H335 WLR primers unburned powder
60.8gr H335 91/2M primer 225gr Nosler 3MOA TOO HOT
56 gr H335 250 grain Speer 3MOA Horn 2.5MOA 91/2M primer
57 gr IMR 4895 225 gr Nosler pt 2.5 MOA
60 gr Win 748 225 gr Nosler pt 3+MOA
62 gr Win 748 225 gr Nosler or 1.25MOA DO NOT EXCEED
56 gr IMR3031 225 gr Nosler pt 2MOA
56 gr IMR4320 250 grain Speer or Hornady .4MOA BEST GROUPING!!!

I shot quite a few more groups, but my notes show too hot or inaccurate.

I've settled on H4895 55 gr and Hornady Interlock. I've had bad luck with Speer hot cores in other calibers - so have not used them on game yet. I've read high praises from others though on this bullet.

When there's a temp insensitive powder from IMR close to 4320, I'll try it.

I shoot the same case necked to .375, and it too runs well with 4895. The H version has shown single digit variations on the chronograph, but I mostly run the I version for a bit more juice. Another powder that's worth running in this case, at least in a fatter bore, is TAC. Where the 4895 were where the best speeds were coming before TAC arrived, with TAC I get some really good numbers on the chronograph.

I necked it down to 8mm with great success.

What a great little case IMO. It really could have been the ideal short magnum but the fickle bunch probably 'knew' the belt is bad.

What surprised me was I thought that round nosed bullets would be best, but the ones I tried would not work at all.

Probably the round-noses weren't very well balanced. Not many companies bothered (and may still not) to make round-noses very carefully, because after all they were "short range" bullets. This means they ran their forming dies long after dies for spitzers would have been considered worn out.

Learned this a while back by using a Juenke machine to test bullet balance. There was a VERY high tendency for all sorts of bluntnosed rifle bullets to be poorly balanced--and they shot that way. These days the problem isn't as common.

Klik,

TAC also works great in both the .350 and the 9.3/.350 wildcat, most commonly known as the 9.3 B-S.