EB, The takedown screw is 1/4 - 28 thread which is a standard fine. The chamfer angle for the hole is not the same as a standard flat head screw though, which are 82�, I do not have any way to accuratly meaure it but it appears to be around 70�, or less. Numrich lists takedown screws for the Model 25, these will work - they are just threaded farther and probably will have a smaller diameter head. I took a picture of different variations but I cannot get into photobucket with their new 'improved' version to upload it & their link to the 'old version' does not work.
Be carefull if you order a firing pin, you probably will get a late version and unless your gun has had the bolt replaced it will not fit & I don't think it can't be made to fit. The firing pin Numrich has pictured will not fit an early style bolt. Later bolts have an obround openning in the top near the front. Savage quit listing the early bolts at least by 1924 (that's the earliest parts catalog I have)& sold updated complete replacements after that. They do have a note to include the serial number of the gun when ordering so they may still have supplied parts for earlier bolts. The 1927 parts catalog states "
The breech bolt as illistrated is of our latest design and should function satisfactorily in your rifle though the boly you now have may be of earlier design." I have ran across quite a few early guns with the later updated bolt.
I finally got photobucket to work - from left to right; early 1903 with angled knurling; late 1903/1909/1912/1914 with straight knuring; early Model 25 (same except tapped farther); late Model 25 with smaller diameter head.