FN509 with SRO stress test
200rnds winchester white box 115gr, no issues
100rnds federal syntech 124gr, no issues
100 rnds federal hst 147gr, no issues
40rnds hornady black 124gr, no issues
25rnds hornady critical defense 115gr, no issues
15rnds sellier and bellot 124gr, no issues
250rnds federal champion fmj 115gr, rounds struck SRO repeatedly with no damage, one malfunction as picutred
will update as i plan to put through some more of what i tested, as well as hornady duty and black, with 250rnds of the monarch zinc coated 115gr. Lots of contentious claims on the 509s performance with an SRO, I wanted to upload somewhere how it performed with specific ammunition. Mine is a 509 midsize tactical, I used a mix of 509 midsize 15rnd, fullsize 17rnd, and the 24rnd extended mags.
Overall, it seems to reliably eject carry ammo, but i want to put that test up to 300rnds before I can confidently claim reliable performance.
I would only by an SRO from somewhere you could return it and exchange for another red dot.
Updated round counts as of 5/16/26, it's easy to tell what ammunition gives problems within the first 20rnds, but i would not consider anything less than 100 reliable. So far, only fed champion has caused any issues, and it was still only a 1/250rnd failure.