Well, we got images of the primary suspect today, so I'm guessing we'll get more pics soon.

Here's what I think we know so far:

• they did recover the gun - reports are saying it's a bolt action rifle, and this article claims to have a shot at the gun, which tracks with this article where a sniper guessed the caliber from the gunshot sound (allegedly a .30-06, which has a similar muzzle velocity and size as the .308 the sniper guessed)
• the bullets were not engraved, though potentially marked w/ permanent marker or something - engraving takes a lot of work, and I doubt someone skilled w/ a firearm would bother
• the primary suspect is the right person - they arrested/detained two others, and quickly let them go
• they have some biometrics - I watched a report where they recovered palm, forarm, and shoe prints, no fingerprints as of yet

I'm guessing the perp isn't a student there, otherwise they would've been able to get a name from school records.

I guess we'll see how close I am, but in the meantime, I hope these sources are of interest to others.

Edit: Looks like they got the guy (Tyler Robinson), and I was pretty close. Some details:

• attended Utah State (not where the shooting happened) for one semester, then dropped out and attended Dixie Tech in St. George (about 4 hours south)
• bullets were allegedly engraved and the text is available, though no pictures AFAICT
• apparently he was conservative, at least a few years prior, though not a fan of Trump or Kirk
• turned himself in when his parents confronted him

We'll probably learn a ton of additional irrelevant details soon. He doesn't seem like a crazy person, just likely radicalized by the internet.