Hi, I bought these screws a few years ago and they've been just about perfect for everything I've used them for, but I've no idea what they're called so I can't find them again! I think I originally bought them in B&Q, but I'm not certain. As you can see there's a second thread with a much steeper pitch. This helps them bite into the wood really nicely, so they're great in a tight spot where you can't get a good angle with a drill or driver. I'm down to my last 2 now! Any help much appreciated, thanks!
Look at the Spax range, sure they wood suit your needs,& Timo do a similar screw both from our host, & TS have twin treaded screws. https://www.spax.com/uk/handymen/screw-finder/products/pozi/pozi-hardened-steel-yellow-zinc
None of those were quite right, but you have led me to them! Many, many thanks, I've been after some more of these for years http://www.screwfix.com/p/turbogold-woodscrews-double-self-countersunk-4-x-50mm-200-pack/12110
Great screws! Shame you just missed them earlier in the week. They were a 'deal of the day' item. £16 for a 1000 screw mixed carry case. Hopefully they'll come up again.
They are a good cheap and cheerful screw, start easily, not bad for not splitting the wood and hold well.
I like the Screwfix Turbo Gold screw as well. Not too expensive (unlike Spax). They drill and hold the wood nicely with a tight grip. Sometimes no need to pilot hole. Also reasonably rust proof. I left some out in the garden for 3 months on the floor - still no rust and look new. After I used these I would never switch back to the very cheap Screwfix more standard screws called "Gold screw wood screws". They are weak, break easily and very poor thread which doesn't hold very well in wood. Always Turbo Gold for general purpose is my everyday choice.