Thanks charles! It still annoys me I lost the spring and detent, but it's not a huge deal. If I could have found the spring, I would have just made a new detent.
I actually had to do that for the rear sight windage drum. It did the same thing but luckily the spring stayed behind. It's not the prettiest thing ever, but when the "metalworking" tools you have are a hacksaw, bench grinder, files, and a drill acting like a lathe, it's a miracle I was able to do it at all. You get creative when that's the hand you get dealt. It works well, actually. For those curious, it used to be a screw out of something I took apart.
I cut the head off with a hacksaw, chucked it in a drill and ran it over a file to effectively turn it down to size so that it would protrude out of the windage drum but without being able to go through it. The taper it wound up being worked to my advantage in that respect. After that, the filing was cleaned up by hand then chucked the other way around to grind it down, in effect facing it to length.
In one respect it feels kinda 'janky' putting your rifle together with parts made with, well, a grinder and a file, but on the other hand it feels kinda rewarding being able to make small replacement parts that do their job as well as the original part.
Here's what that detent looks like if anyone's curious.
Right now I have a brownells spring and DPMS detent (plus an accu wedge) sitting in my cart over at Brownells; the spring for 1.99 and the detent for 1.19. I'm contemplating taking advantage of free shipping and going this route instead of the AR stoner kit. From what I read, they're pretty hit and miss, and when they do hit the nail on the head it's 'meh'. I don't think the best of DPMS either, but I'm not sure how they can screw up a detent, when it's effectively a short piece of rodstock with semi-coned / chamfered ends. I could probably save myself a $1.20 by making one myself from a finishing nail by cutting it to length from the head towards the tip, filing off most of the tip and remembering to put it in the right way around. I haven't bought anything yet, as I'm still deliberating. I've got until midnight.