Well to add a little in regard to Bigtoe's spread, I recently rebuilt a Webley Stingray for a guy, it was .22 and the older UK barrel, I had a nightmare of a time finding a pellet that gave consistent results, I tried, FTT, AA Field, Superdomes, Bisley Field, Hobbies and Falcon Accuracy and then resorted to Caledonians and Wasps!
The AA field gave a huge spread of up to 75fps and the other modern pellets were not much better, and it seemed it was all down to the skirt and how it sat in the end of the bore, I noted the lead in on this barrel was more bell mouthed than my own .22 Webley barrel and that got me thinking!
In the end I was weighing and measuring wasps for a consistent 14.4 grains and a 5.52 head size, this helped but I still had a 30fps spread, which to me was unacceptable, I then made up a little jig with a ball bearing and a press and flared the skirts on the pellets, hey presto 10fps spread, no matter what pellets I used!
Put simply the barrel was obviously flaring the skirts in a different manner dependant on the thickness of the skirt, it's initial width etc, flaring all to the same size resolved the issue, but oddly lost me 20fps , but at least I was able to get a consistent result over the chrono to ensure it was legal.
Of all the pellets tested despite some being similar weight the Caledonians consistently have a higher output by up to 25fps!
Some barrels are just fussy!