Don't try it. I don't know what finish they use, but you will need a jack hammer to get it off. I have been applying Jasco for three days now, I think I need three more, and that's before I can start sanding. Next time I will just buy a new stock.
This is an older AL390, the stock actually cost as much as the gun does, because it is Black Walnut. I do not buy plastic guns. But nice try at being funny. I did find out that this is a two part finish and it is hard as nails. It will be another two weeks before I am finished, but I will post a pic.
I would use Tung Oil or Tung Oil Varnish after staining. Put on seven coats. Tung Oil is the most resistant to water other than Teak Wood Oil which is very expensive. Rub it with 0000 steel wool between each coat. The Tung Oil Varnish will dry faster. It is much better than Linseed Oil with the driers. Ned S
That's where I am now Jon, first coat went on this morning. However, I did buy a plastic gun yesterday, almost on impulse. I was in my LGS and Jeremie says look at the new 400s, they moved the KO, it's more water proof, woo, woo, woo, and I'll give it to ya for woo. At least now I won't be fighting over the old 400 with my daughter.