I have refinished a lot of stocks and always use aircraft/marine grade stripper. It takes 2-3 repeats with this strong stuff and wouldnt mess with low powered stripper. Mop it on heavy and wrap it in saran wrap or something similar to keep it from drying out on you and to let it work longer so you dont have to work as hard!
I use a stiff nylon or soft brass bristled brush to work in the stripper too. Let the first coat soften the finish and start brushing with the second coat of stripper. You'll want that brush for the checkering also. Just dont get very agressive with the brush on the checkering.
When I think the stripper has done its job I wipe the stock down the best I can and then wipe it down again with plenty of laquer thinner. The stripper will pull stain out of the wood and so will the laquer thinner but the thinner helps clean off the stripper. And I dont know if my last step is necessary , but I do a final wipedown with denatured alcohol to neutralize anything that might be remaning on the stock and to clean out any nooks n crannies that need it in the inletting.
Ruger uses some sort of a tinted polyurethane finish and it doesnt go very deep into the wood so its pretty easy to remove. I think my refinishing using a stain and clear poly look better and is absolutely more durable. Minwaxs "Gunstock" color is a very close match to Rugers color and if you mix 15% to maybe a max of 20% of dark walnut to the gunstock , it will still have the reddish brown color but really help to pop the grain.
This is a 77 Ultralight with straight gunstock color I recently did...
And this is an old Rem 721 just done and I used 20% dark walnut in the mix since it wasnt quite as red as the rugers usually are. It still has quite a bit of red in the color ,more than I thought it would , but made a nice difference in grain constrast. I'll be doing my next Ruger this way.
Im no expert by any means but have finished quite a few and have done tons of wood windows and cabinets for customers that give new meaning to fussy! If you have any more questions I'll help out if I can...