Hi Bruce,
I'm not sure on whether the Sellier Bellot projie is the Highland by another name these though being a FMJBT have and open rear so would I surmise upset a bit I shot the Highlands in my comp No.4's they fly very well.
Sadly as you know the chap who tried to resurrect Taipan Projectiles closed it down due to thieves and break ins and damaged equipment.
They were the best projies I came across being .312" 174gn HPFB they shot beautifully I managed to have an original 100 from Malcolm Bones day and squirrelled another 400 odd before the bust just could not afford to buy 2000 of them.
I also lucked onto 400 174gn FMJBT's Highlands a little while ago (3 years) so have @500 of them tucked away for a rainy day but the bulk of my 303 are Sierra's which can be fickle depending on load.
I have had good success with the Hornady .312" SPFB 150gn they fly very well indeed I've only shot them to 500m out of my 2 groove No.4's they go pretty good.
Have a look at the Projectile Warehouse in S.A speak to Rusty (08) 7325 0390 they helped me out and have a large selection of projies on hand I was told Hornady were not making the 168gn .308 A Max anymore by my G/S.
This proved to be a fib as I got 500 from Rusty and they had plenty more in stock it's what my APRS shoots although I tried the 168gn FMJ and luckily it is the same POA, pretty disappointed in my G/S saying they could not get them!
See pic how I load them with a medium crimping into the cannular.