remington model 12A eject problem

[3-tours]

I just today bought a rem. 12A. Its serial no. is 228xxx. It's in great shape other than some of the blueing rubbed off on the barrel. The stock looks mint not a scratch or dent on it. On top of the barrel it says REMINGTON ARMS-UNION METALLIC CARTRIDGE CO.,REMINGTON WORKS ILION,N.Y.USA. PEDERSON'S PATENTS JAN.5,1909,OCT.12,1909,MAR.81910,NOV21,1911,APR.16,1912. In back of the rear sight it says Remington trade mark .22short.long or long rifle. Now to my question; I brought it home and cleaned it, reassembled it and put 3 rounds of .22 in the tube mag. 1st round was winchester wildcat solid lead slug high velocity the next 2 were remington high velocity 22 long rifle solid lead slug, also on the rem box it says extra power cartridges. after I fired the first one, i could barely pull the slide back to eject the spent cartridge. I fired the second and had the same troubld and so on with the third. the accuracy was excellent. Any help on why ejection is so hard? other then that the cycling is flawless.