Hi guys, so i just made my first mod, nothing major, i just wanted resist and fortify potions to last longer. I tried to alter the magic effect "alchfortifymarksman" on the magic effetc list, but it didnt work, so i figured that was not the way to go about it, would be nice really, but the way i found was to modify the values on the ingredients themselves, by going on the ingredients list, and modifying their durations from there. Everything is working now, except marksman, i did change all the durations on fortify marksman effects on ingredients to last 5m, and now i tried changing it to last 300s. But still when in-game every other fortify skill and resist potions last 300s but fortify marksman still lasts only 60s. What am i doing wrong?

Hard to say. From what I can tell, altering the ingredients is the only way. Have you double-checked the changes?

Edit: I just tested it myself and got the 300 secs with a fortify marksman potion.

Yeah all the ingredients are right, triple checked it. I would upload the .esp but there's no option for that here. I'm starting to think it might be another mod, going to load up tes5edit and check it out.