Sorry, I should have been clearer on what I was saying. Didn't mean that there was something wrong with the pellets themselves, just that they (JSB's) may not load well from the magazine to the barrel. I have one Bantam that shoots H&N field target trophies in 4.52 best and the JSB 8.4 clip going in from the magazine. I can single load the JSB'S but the H&N pellet is more accurate Tried the H&N 's in 4.51 and 4.53 also but not as good as the 4.52
My other Bantam in .177 shoots the JSB 10.34 best and the H&N's are all over the place. I have 2 magazines for the .22 and a total of 4 for the .177's. Change magazines and the results stay the same. The magazine on the Bantam may just be the nicest part of the whole package.
Good luck, hope the replacement magazine fixes your problem so you can get back to enjoying a great gun
Doug B.