Hi Andy, I use a £10 blast gun from Aldi Lidl with a 2.5hp compressor. I buy a bag of bicarb from the local animal feed stockists.
It works for me. I posted a bit about it on the other forum.
Just bought a second gun as it was on clerance for £6 so couldnt resist. I also bought a needle de scaler, clears scaly rust like a powerfull blaster but much less mess. Been using it on a tractor chassis. Look at needle scalers on u tube.