While it is possible that the feedramp is the problem, I doubt it. It should feed FMJ ammo, at the least.
Charlie is right that the problem is hard to diagnose without seeing the gun, and I too suggest taking it to a gunsmith. However, since this is the internet -- and a certain amount of speculation and gratuitous suggestions are expected [ :wink: ]-- I'll offer a couple of comments.
As a blowback gun, proper function is going to depend on achieving a balance between the recoil force of the cartridge, and the forces resisting that recoil, such as the slide mass, slide friction, and recoil spring and hammer spring tensions. Even the magazine spring tension pressing up on the slide plays a role.
Since you have a used gun, it is possible that the gun springs are worn. I could see how the "pauses" you experience could be due to a weak recoil spring. You could try ordering a tune-up kit from Wolff and replacing the springs. On a blowback gun I suggest replacing recoil and hammer springs at the same time, though you may have to experiment with different weight hammer springs to optimize functioning.
Also, while you say the pistol is clean, make sure it is properly lubed.
Make sure your magazines are in good shape, especially the feed lips.
Also, try a couple of more different kinds of ammo and see what happens.
The above suggestions range from free to relatively inexpensive, and generally fall within the do-it-yourselfer prime directive ("First, do no harm"). If things still don't work after trying them, then get thee to a good gunsmith.