Yes!!!, I know that all air rifle barrels are not the same even on the same make and model rifle, the barrel diameter can be larger or smaller and the rifling is also a little different its like a finger print....please!, see link bellow very interesting reading and info indeed, and proves the point in regards to head size of pellet ect.
see bellow link.
http://www.vogelusa.com/pellettesting.htmTherefore, pellet testing, matching amo for one's barrel is a must to achieve great accuracy, Whatever people say about pellet head size and batch no, I do believe without any doubt it really do's make a difference to accuracy, For many years no matter if using air guns or firearms finding the perfect pellet/bullet for ones rifling and diameter of your barrel will be as important as shooters skill and technique to achieve and strive for best accuracy.
Having tried and tested just about every pellet I could get my hands on over the years I can say without any doubt the best pellet ever,,, in any of my 4, Air Arms spring rifles which include TX200HC,1 and TX200HC,2 prosport and TX200 full length.
The JSB EXACT EXPRESS,4.52 787,gr, and AIR ARMS EXPRESS,,, have given ultimate accuracy even out to extreme long ranges at 90+ yards. this pellet has even gone through the same hole @ 50 yards on a very calm wind free humid summer day.
I highly recommend you try and test JSB EXACT EXPRESS and Air Arms EXPRESS pellets in you Tx200's and prosport.
The JSB express 4.52 AND AIR ARMS EXPRESS,,, also work incredible outstanding long range accuracy in my Weihrauch barrels my HW,100T'S loves them and so do's my 97KT and HW,77, HW,45 pistol and Alecto, top accuracy amazing pellet.