JG Bar10 sealing issue

Rifle background(shooting around 550fps):
-PDI spring, spring guide, piston, trigger assembly, and sear
-6.03 long barrel
-firefly hard bucking
-rest of gun is stock

If anyone remembers my previous posts I described how the knubs on my hopup lever broke awhile back so I used a cut in half bb resting on the lever to apply hopup which gave me amazing accuracy at 80m. My firefly wore out in the last couple months so I made some changes until a new firefly hard bucking and the dangerwerx B type lever came in.

When they arrived I installed them, cleaned the barrel, regreased the trigger assembly, and relubed the oring on the piston. No actual changes, just a cleanup. Piston seems to have a good seal as it will not freely move in the cylinder.

Upon testing I found the gun to be loud(like slamming) and accurate only to 50m. The dangerwerx arm didn't really apply enough pressure to get a good hop(though I believed this may be a result of the sealing issue) so I added just a dab of hotglue to it and made it as even as possible. Hopup is better and sound was a smidgen better but accuracy was still only 50m. I then replaced the dangerwerx arm with my old flat lever + 1/2 bb. Same thing.

Summary: The gun quiets down and shows good sealing only after too much hopup is applied. Even so, the accuracy is appalling to my normal range. Thus, I feel I have two issues.
1) Sealing problem
2) BB issue

I tried Airsoft GI .4's, Madbull .4's, and soap washed Madbull .4's and they all came with the same results. Every couple shots I get a dead bullseye shot and the rest curve wildly to one side or another. The Madbulls are a bit old and seem to be multicolored as if whatever is coated on them has been worn off or evaporated. Can get pics if need be.

Final note: I never really attacked the sealing problem because I never had issues before and since I haven't changed anything I wanted to believe it relied in the bucking.

Any help?