For those with FX slug liners in .25 and .30 caliber

Bio-man, Regarding the NSA .25cal slugs, are all of them that you are using - Flat back or Dish base?

I have a moded 25 cal. with the FX Power plenum kit using a 700mm slug liner.

I have tried the NSA FB 33.5 and FB 29.0 with no luck regardless of reg. and hammer spring settings.

Only head way I have made with the NSA's is the FB 29.5 gr at 940fps which will literally shoot hole in hole from 7yrds to 40yrds beyond that range the grouping opens up to a 4" plus erratic cluster no matter what tune I try. I have yet to try the 36 gr. (Note: Reg pressure range tried 115 - 140Bar).

NOTE: I also shoot the MKII's with this setup and they are tack driving from 7 to 100yrds at 940fps. (reg. pressure 115Bar)

I do pest control and would rather shoot hollow point slugs over pellets as the terminal devastation is much greater. 

Thanks in advance. 
 
AM

Pretty much everything I shoot is flat backed and .250 diameter. The .249 slugs do not seem to shoot quite as well in my gun. I have shot the NSA 33.5gr slugs at 740 up to 940 fps with MOA accuracy at 100 yards. Seems to be an accuracy node at every 20fps or so mark. Then again I tuned for each of the velocities I shot at. The reg is set at at 130-145bar and some kind of plenum installed for most of this. I think I am settling on the NSA 36.2 as my go to slug of choice. I am still shooting paper at 100 and spray paint cans at 200 yards as I have not looked for a permission yet.

I wish you luck in your quest.