Bronze wool? Citristrip? I'm sure the advice you have been getting has good intentions behind it, but if you use those two methods you will hurt the value of k98k. No question about it.
No bronze wool, steel wool, sandpaper, emery cloth, etc on a German stock, period. You may get away with that method on a molested RC k98k but that's about it....
Citristip and other chemical cleaners are harsh chemicals. Some do less damage to wood, some do more. Notice how the wording on the product is slightly skewed. "Safer than other paint strippers" doesn't mean "Safe" and "Can be used on wood, metal, etc" doesn't mean "should be used on wood" or "designed to not hurt wood". Citristrip is most likely the best of the bunch since its "non corrosive" but it still has its negatives. Wood is organic matter and the wood's fibers get dried out and become brittle from these types of chemicals. It is best to avoid them. When you run a search, the majority of chemical stripper users also many times end up sanding and completely refinishing their stocks so with all do respect, their opinion on the matter doesn't really apply unless your going to be totally refinishing the wood.
There are chemical free methods that are always worth a shot before moving on to chemical ones. The duct tape method is my personal number one choice. If your not aware it's basically consists of giving your stock a bikini wax. Press on a strip of quality duct tape and pull off... Now some shellac is stubborn and a good varnish will resist the duct tape method so you need to give it a test to see. Benefits are no smell, no chemicals, no damage to wood.
Second chem-free is the "scrape or glass method". You take a very small plastic scrapper or a piece of glass (use caution) and at the right angle you scrape the shellac/varnish off. This is extremely time consuming but if you take your time the results can be very nice. Benefits are no smell, chemical free and the satisfaction that you can be proud of working on a stock for hours. You can also use a combination of duct tape/scrape method...
Now if those methods don't suite you.... Try denatured alcohol first. Soak a rag and wipe off. In my experience its much easier on the wood compared to acetone. If it won't come off with denatured alcohol, them it's most likely varnish and acetone will take care of that.... Neutralize the wood with mineral spirits when your done.
The completion step for any of the "removal methods" would be Howard's feed and wax IMO. My advice is give the chem free methods a chance before rushing into the chemical ones. My buddy turned his stock into having greenish tint because many folks recommend the oven cleaner method for cleaning a stock.....
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