I've been welding a bunch of 1/8" wall square tubing together and I've been beck welding stringer beads to counter the warping... All of my fillet welds are perfect, but when I weld the 1-1/2" long stringer bead- I get a little butthole at the end EVERY TIME. I've tried going back into it, swirling, back and forth- to no avail. It won't affect anything- but I hate the way it looks...
Are you tapering off when you swirl? An extra dab of filler at the end helps to. It looks like you need to clean your workpiece some to. There's a lot of contaminate just sitting there.
Those are stick welds. A big deal in Europe is to attach a pendant amp control to your (capable) stick welder, and adjust it as you weld, with your opposite hand, and then taper of the amps completely at the end as with tig welding. Don't break the arc.
In your case, I would break the arc, wait a second, and then do a little dab on the crater, before the pin hole forms. (As in whilst still very orange hot.
While you weren't specific about the 308 rod, I was reading so many forums I missed that you'd posted in the SMAW forum, and should have noticed...
The same "button-off" advice still works, but the method is different, obviously. At the tail-off, I suggest you long-arc it a good ways until the puddle begins to chill, and dive back in for a good half-second. The actual timing will take some practice, but the idea is the same.
While I think in your case that li'l dimple is harmless, the ultimate solution would be to do half the weld from each side, meeting in the middle.
Problem with welding ss with stick is a lot of heat. I think your puddle is getting very hot towards the end of the bead and the filler metal is somewhat sinking into the base metal more. Try with the rod angle - when nearing the edge slowly turn the rod in the opposite direction so you should "slide" the rod over the edge of the pipe with a push (go a little over the corner). Watch your weld speed and watch for undercut or spilling over. And keep a tight arc length, don`t extend the arc length otherwise you will get the thing even more hot.