After playing with the NSA 24.8's in .216"-.2175" sizes, Sniper showed a definite preference for the .216" and .2165". With the current reg setting(130ish bar) she pushed them to right around 1,000 fps max velocity...so I backed the HST down to 950 fps(49 fpe) and that's where I did all my testing with different slug sizes. It comes to me now that I should have experimented with velocities from 925-975 to see if I could really dial in the accuracy potential...but I've since switched back to FX Hybrids. On the accuracy of the NSA's, I was achieving 1/2"-3/4" groups regularly with the occasional 5-shot group at 50 meters coming under 1/2".
I was pretty happy with that...but the starlings weren't. I really put a hurting on them in this area with my longest shot being 85 meters. The NSA's @ 950 fps MV pleasantly surprised me on the terminal performance. The HP really did it's job well with a significant "POP" upon impact and every bird that I hit died...all quite immediately with significant damage to most. I digress...
FX Hybrid's(incidentally, the NSA 24.8 grain slug and the FX Hybrid 22 grain slug have the same estimated BC of .080 despite the NSA being almost 3 grains heavier and .2 mm shorter)...my first tests with the Hybrid's revealed that Sniper pushed them to 1040 fps max velocity which was a bit faster than I initially liked. However, I was feeling in a tinkering mood one day and decided to try them again for grins and giggles. I backed off the HST 1/2 a turn and shot a few...at around 1000 fps and yes, accuracy was not great...roughly 3/4"+ groups at 50 meters. So, I did what I should have done with the NSA's...played with the speed dialer to experiment with velocities. 875...no good. 940...money! It still needs further tuning but currently I can regularly put 3 shots under 3/8" at 50 meters. Also great is that it's using 2.2 bar/shot which means I can get at least 55 accurate shots per fill...I like. So far, I've dispatched a starling at 45 meters, a dove at 75 meters, and a pigeon at 118 meters. Accuracy definitely kills! The estimated .08 BC of the Hybrid's seems close but it's hard to tell without some serious downrange time.
I'm pretty happy with the accuracy results of the Hybrid's out of the 700mm CZ barrel but they are only doing 44 fpe at the muzzle and so wind drift may still be a struggle to deal with if I want to accurately shoot past 100 meters.
Maybe someday I'll turn up the reg and try some heavier NSA's for better BC and downrange performance but for now...I've got six trays of Hybrid's on the shelf and it's hard to mess with this kind of accuracy and shot count...
^5 shot group at 50 meters...130 bar reg, 940 fps, light wind
....hope it shoots slugs how you envision! 
