[Chaz]

You could always go longer and add a suppressor to the end of the barrel?
From what I have seen tightbores are slightly over rated. Read up on polishing and waxing your inner barrel. I have had great results in terms of accuracy.
Tightbores just help increase FPS.

 

[Chaz]

Try polishing your current barrel - this might be enough.

Best to try this before dropping the money