Hatsan Bully 25 cal initial shot strings - slug data

I got back out to the IndianaAirguns.com range on Sat. Before I start tuning the Hatsan Bully 25 cal, I wanted to get baseline data on slugs. The temp was in the low 50's. All slugs fit in the Hatsan Bully magazines, including 55gr NSA ammo. While shooting, I noticed some slugs pushed right. The more surface area engaging the rifling, the more it pushed right. The 55gr pushed a full 5” to 6” right. Like pellets, specific slugs seemed to perform well around a given speed. Probably barrel harmonics. H&N Grizzly's were on point around 880 to 900 FPS. The mid weight NSA slugs were on point at around 900 to 930 FPS. Any faster and the groups opened up. The gun can be tuned down to shoot Grizzly's, or NSA 39gr. NSA 44gr shot at a perfect ~900 FPS for almost a full mag.
Had some problems with the Chrono toward the end of a few shot strings,and didn't capture the end of the strings. Here's some data and shot curve chart:

1525047419_5644839275ae6607b1a8253.53176163_Hatsan_Bully_25cal_slugs_1st_shot_strings_Mag_aver...png


1525047434_7839487215ae6608a0c2324.27291743_Hatsan_Bully_25cal_slugs_1st_shot_strings_graph_sm...png


-Rich

EDIT: To better see the chart data, right click and select "Open Image in new tab". The photo will be larger in the new tab.