The ESP Guitar Company

I turned one of them by hand about half a turn and heard a slight cracking noise (probably the lacquer) so immediately stopped and I'll be buying the old version of the schallers instead! 

I wouldn't ever consider the noise I've heard installing them as 'cracking', but our idea of cracking might be different. Depending on the side of the existing holes from OEM strap buttons, you might need to drill it out a little first before installing strap locks. You might caused some internal fractures by putting too much pressure on the wood. I suppose if you don't see any damage, probably not much to worry about. 

I use the s locks on all my guitars and only had to drill out the holes a little in one (LTD V-500). It was fairly obvious that the S lock screws were massive compared to the OEM screws. 

Thanks for replying! I literally did half a turn on this new one and it made a tiny cracking noise so I stopped. Obviously with it being a brand new guitar, I don't want to damage it within a day of getting it. From what i can tell, the OEM screws are about 0.5mm smaller than the schaller ones. Maybe in a few months I'll be brave enough to drill the holes out a little but for now I'm gonna get some of the old style schaller buttons and use the OEM screws

I put them on an LTD Truckster with no problems, the Schaller screws were longer, but I just screwed them in until snug with no drilling.