I use polyurethane and it is by far the most hard, durable, chemical resistant and attractive finish in my opinion. True oil or tung oil don't come even close in terms of durability and chemical resistance.
It's fast drying and very easy to apply in aersol form, which provides a nice, even finish without the brush strokes that you get with rub on finishes.
The downside is that once it does gets scratched or worn you'll have to strip off the finish or sand it and redo it, where as with tung or true oil all you need is to rub on a new coat and it's like a brand new finish again.
Despite that, I still go with polyurethane for most of my wood finishes. They're also available in satin clear, semi gloss or gloss, quite convenient.
Here's an M1 that I refinished in polyurethane satin clear:
I would vouch for it's durability, it still looks this way till this day.
I presume that you want to refinish some AK wood?