There are more than one type "corally" plug out on the market. You have to be very careful and just keep to one brand. I used to always keep to genuine corally ones as i always thoughts theirs were better than any others.
These different brands are not all the same. You can have plugs that won't fit tubes, and plugs that are loose in tubes. None of this is good!!
They are all "gold plated" (maybe!) which in truth as a material is crap as far as conductivity is concerned. It's a material that is used purely as it doesn't corrode easily.
The LRP silver ones would be much better in this respect - silver being the best conductor of electricity (yes better than copper).
........and one of the best (funniest) reasons that i ever heard to solder was that a driver was too tight to buy corally's - as his sponser didn't have them!!! made me laugh.
Personally i (generally) solder my cells in, all classes. First did it 12th scale as it was actually easier as it took up a lot less space inside the car. Some of my practice cells still have corally's on them - as i can't always be ar**d to solder at club meetings
