SU35
I was also sceptical when I heard about these figures from a 300wby. I have seen these loads myself over a chrony about 2 months ago.
I started playing with Rel25 & 150gn Speers myself.
Being cautious with my handloading I started at 95.0 grains rel 25 and worked up to 97gns - just out of curiousity.
My results were 95.0gns/3520fps, 96.0/3560, 97.0gns/3620fps average over a 3 shot group.
I left it at that - mainly because for what I want I do not personally have a use for a 150gn projectile at these sort of velocities.
I have been handloading for 15 years - long enough to know conventional pressure signs when I see them. There were none. I miked my cases (once fired), there was no sticky bolt lift, marks on cases or anything like that. In fact the case necks were still sooty.
The groups from my rifle were not particularly good - and I got the impression that maybe another grain or 2 would have tightened the groups considerably - something that is normal for the Roy rounds when they are not producing enough pressure.
I have not bothered with it anymore as I still think the 300 does its best work with a 180 projectile.
These loads that 340wby talks of have been tested across about 4 different rifles all with very similar results.
Not suggesting that anyone should attempt them - but with Reloader 25 and a 150grain projectile ONLY, this combination would appear to produce exceptional velocities without any normal signs of pressure in the 300Wby.
