If anyone needs gas checks for .33 or .338 I have some.sunray said:Yep. Likely a .33 Winchester CF(aka .33 WCF). It was Winchester's first medium bore cartridge back in 1902. It used the same bullet diameter as the .338 Mag. Drives a 200 grain bullet at about 2100 or 2200 fps. A 250 grain bullet at 1900ish fps.
It came in the Winchester Model 1886 lever action originally. Later in the Win Model 1885 falling block and in the Marlin Model 1895 lever action.
There's lots of on-line info about it and you can still get dies and brass for it.