My only experience of "budget" pellets in recent years was with some Marksman in .22. I only tried them (briefly) in my 2240 pistol, intended purely for the back garden. Not good. May have performed better in other guns but I wasn't tempted to try. They looked quite "shabby" and almost of oxidised appearance. I'm not sure if that's how they are or if they were very old stock?

Back in the day my worst shocker with pellets were the Lane's Heavyweight Special. Awful. They differed hugely in length from one another, maybe by as much as about 1mm?