True oil will do a good job, but you must prepare the wood, then put on multiple coats allow it to dry in between and rubb with 4 ought steel wool wipe down and continue all over again till you get the finish you want. You can also rotten stone it after you get a good finish to really set it of. This is a true oil finish.
There are several good videos on you tube on refinishing a rifle stock. I have done several rifles with Birch wood Casey tru-oil if you take your time and follow the directions it doses a beautiful job. I just did a Savage I bought off a forum member on here. I striped the stock, lifted some minor dings with heat and a damp cloth, I then stained it with a light walnut. I finished it off with fifteen coats of the Tru-oil. It came out beautiful.
I've been using formbys high gloss tung oil finish..while not 100% pure tung oil it works well and dries faster...
I prep the wood..then thin the finish 3-1 or 4-1 mineral spirits to finish...I soak a heavy coat in..next day a 2nd..that's the entire stock..thinning it gets the oil to penetrate better..and dries faster..
Then I start coating it...thin coats rubbed by hand..let dry a day..0000 steel wool works..I've also been wet sanding between coats..more work but I like the results..
Continue till pores are filled..then like John said pumice and rotten stone will polish the finish to the highest gloss and remove "wet" looking spots and imperfections etc..then wax it..
I tried truoil and just couldn't get it to look right..don't know why...many guys love it...
I haven't had the tung oil finish outside yet but it seems really tough and water resistant...it is a lot of work...but I enjoy it..
Hate the Birchwood Casey finish. Way to glossy and it chips and mars easily. I stripped off the finish I applied to one rifle the same summer i applied it.
I use tung oil as a base layer x 3 coats. Let it dry up several days between coats. Then use 0000 steel wool and go over it well. Make sure to remove all dust and particals before applying another coat.
After the last coat of tung oil - let it set for a full week or longer (after final sanding with 0000).
Get a can of spray on Minwax Helmsman Spar Urethane. Pick your poison - gloss or semi gloss. Follow the application directions closely!!!
Build up multiple coats and do the steel wool (0000) between aplications. I applied about four or five coats.
After final steel wool buff - get a old nylon stocking. Cut a wide strip of it without any seams. Buff the finish with the intent on "warming" a section. No need to go caveman - your just buffing it up.
You know have a fully waterproof stock that the woods natural bueaty shows through. The finish is also tough as nails.
Most important - remove all the old finish. Then make sure that the stock is baby hiney smooth!!!!!!! Look up the many video's for wood stock pre finish prep. Follow them!
If you want to stain the stock - do it before applying any other finish.
I use Jasco Premium Paint & Epoxy Remover available at Lowes in a quart size. You need latex gloves!!!
Also buy some plastic putty scrapers, a couple of cheap chip brushes, and find yourself a old tooth brush. This stuff is waterless - on and off.
You apply it and let it sit and work. I work over a large plastic tub (something to contain drips and the old finish.
You scrape old finish and this stuff off with the putty knife. Then with paper towels and mineral spirits wash it off and stop the stripping action ( get a can of mineral spirits and some extra brushes for the heavier areas and checking too).
Make sure you have everything. Wear safety glasses and a old long sleeve shirt.
Some finishes come off easily. Others are tough. You may need to repeat the process on parts of some stocks. The back side of a plastic knife is handy for scrapping tough areas - gently..
Once done, if you have some light finish left - sand it off. Then let the stock dry out for at least a week.
The old Remington and a few others has a stain that will "bleed" red. Just keep after it.
Before you start stripping - have everything ready. No dogs, cats, or kids in the area. Read the stripper directions well and everything will go good.
This stripper does not raise the grain at all. Though it seems involved - it is one of the better strippers out there for this sort of stuff.
0000 is your friend as is several pairs of old nylons. The only thing more important is taking your time and not rushing the process. If the directions call for X time between coats take the time. Then only proceed when everything is right - if things seem tacky - wait.
*** A note on the spar finish***
I have this finish on my deer rifle.
After three seasons of hunting bear and deer. With all the travel, moving through brush, slips, trips, falls, and at least one inadvertent slide off a tree when leaning, this finish looks as good as new.
It has been rained on for several days on end. It has been snowed on. Froze, and even had fog freeze on it. It has been ice coated as well as severally dusted.
It still shines, and is impervious to moisture.
I did the finish 360 degrees. Inside, outside, and under the recoil pad.
I used nearly one full can of the spray. I did remove a lot of the spray between coats and left lots of time between coats.
The wood grain still comes out clear with all the details in the grain showing through.
It may not be a traditional finish for firearms. But, it works great.
On checkering, apply one coat and allow to fully cure. Then tape off the checking and continue to finish the rest of the stock. At last coat of the stock, apply one more light coat to the checking. going to heavy will fill the checking in.
Take your time and have a light finger on the button. You will know real quick if you went to much. But when wet - a good clean cloth takes off errors.
If you get lint while cleaning checkering - wait for everything to dry and use 0000 with a old tooth brush slowly and gently.