I doubt the quality of that barrel is the issue. I suspect if you swapped it with a stainless Steel PDI of the same size the results would be the about the same. Try a heavier BB as well. My sons stock Mauser shoots quite a bit better with premium .30-.32 bb's over medium grade .25's. Quite noticeably actually. Bump up the hop up with the heavier bb.
If that fails check into hop up slop and what not.
In general a 12 inch overall grouping at that range with occasional flyers and a few tight grouped here and there is kinda normal.
If that fails check into hop up slop and what not.
In general a 12 inch overall grouping at that range with occasional flyers and a few tight grouped here and there is kinda normal.