Barrel "Conditioning".

[dirty harry]

exellent thread, never even thought of that but when you think about it it makes perfect sense, different lead grades and batches will slightly coat the barrel and end up with a collection of different grades causing slightly different drag factors inside the barrel i would imagine.

[Johnnytopshot]

Your probably right for 99% of gun/pellet combinations, however, I used to shoot a combination of a Daystate Huntsman with H&N Barracuda and H&N Field Target Trophy for several years in the field target world. From memory i used to use Barracuda (10.6 grains) out to 45 yards, and Trophy (8.8 grains) 45-55 yards. There was absolutely no problem switching between pellets at any time, the Trophy pellets just flew flatter and a couple of inches higher, no left or right adjustment whatsoever, and consistency and accuracy with both pellets at all times. However, with every gun since, using whatever pellet you care to mention, I would agree that there is a short 'settling' period after cleaning the barrel, or changing between pellets, or even between different batches of the same pellet.