Mini 14 question

My Dad had a Ruger Mini 14 Ranch (186 series) that was shipped in 2001, so compliant with the rules of the time. Presumably an 18.5" barrel and 1:9 twist. After the ASW ban expired, he tricked it out as an FU to the government. In addition to dreaded 20- and 40-round magazines, he had a Tapco adjustable stock w/pic rails (also a BC folding stock), a "sniper scope", a "sniper bipod", a fore grip, a barrel shroud, and a birdcage flash hider--alas, no shoulder thing that goes up. Basically everything that gives the haters nightmares.

My question: since I don't think barrels back then were threaded, what is this flash hider and how did he attach it? Looks like there's a pin that isn't welded and it has wrench flats so did he have had the barrel threaded? It has a flat cutout with threaded holes to take a front sight. Mostly wondering if it can be returned to original since he kept the stock (but not the front sight). Thanks!

Attachment 90591

Being as the flash hider is on a Mini-14....

I would tap the pin out and see if I could twist the flash hider with some gentle wrench application. With only the one pin, removal shouldn't be too hard. Just be gentle. If you want to put it back, apply a little grease before you do. I have a military/police model Mini with an entirely different arrangement at the muzzle. I don't know if Ranch models had pins in the front sights or not.

Attachment 90594

This is the one I took off my dads 181 series Mini 14 last year.
It was pinned in but easily removed. A rubber mallet help knock it off.
It was not threaded.

Roll pin. Very common on Mini-14's. I had an old Mini with a roll-pinned flash suppressor too.

You should be able to tap the roll pin out with an appropriate sized punch. A little heat (not a lot) might help.

Looks like a set screw too, I'd try that as well as any pin. Also looks like some sort of barrel shroud thing on there too. I think that muzzle device is some sort of grenade launch or blank adapter or something.