I've used stainless steel bolts similar to that dowel for weighing down hop bags, nowadays I only use that for dry hopping in the keg ( as it is just as much a of a pain in the ass to get out of a carboy as a bag weighted with marbles).
I would recommend dry hopping with pellets and then allowing a good 2 days at 35 degrees to drop most of it out, A slightly larger batch size really helps too so you don't have to siphon anything off the bottom. I switched to this method about a year ago because i was getting sick of trying to find an adequate straining device for my siphon.


