PLEASE HELP !!! My APS ASR-110 started to crush BB's

I've been tinkering with an old non-working APS ASR-110 replica for a while now that I came across here on the forum. I am trying to make it for a disabled colleague Anton from Sofia. It had a burnt contact group and wiring, and the piston had split lengthwise and the toothed rack had seized and destroyed the cylinder. I replaced everything that was damaged and after two days the APS was humming. However, there was one significant problem: a 220 mm barrel with a cylinder volume below 5 cc. It blew the pellets in all directions due to the excessive amount of air fed into the very short and small volume barrel. Anna's handicap tournaments are basically target and object shooting. The optimal ratio which should be 1.8 to 1 here was 1:1. So I bought a barrel with the correct barrel (380mm) here on the forum which achieves 1.8 to 1. And here something strange happened: The replica began to crush pellets and expel them through the muzzle of coarsely ground salt. Before I changed the barrel, it was eating perfectly. I did the disassembly and assembly according to all the rules (it's not the first time I've done this) I put the old rubber, thoroughly degreased the lips and the port, checked the nozzle-chamber alignment with an assembled barrel with rubber and hop chamber I passed the tests for unobstructed feeding, for double feed and for passage in both directions. Everything top. the compression nozzle-rubber is normal ( I cracked my cheeks from inflation 😉 ) I put it back together and the rifle continued to behave like a coffee grinder, not like an airsoft weapon... Inner and outer barrel do not have a gram of clearance, everything is heavy, in a word EXCEPT THE NEW BARREL EVERYTHING DIFFERENT IS THE SAME and I really don't know what to do.
If anyone has a similar case or has an idea what went wrong PLEASE ADVISE !!!