I am currently considering building a 338 Remington Short Action Ultra Mag. and am looking for past experiances or helpful input. I will use either a Ruger Mk II, Rem 700 or a Mauser 98 action. I am still considering which.

" First There"

If you aren't too far, keep in mind that you may not have to. Ruger is getting ready to release a 338 RCM (Ruger Compact Magnum) which they are claiming is close to the 338 Win Mag in performance.

The above advice is 100% correct ... buy factory if you can ... and the 338RCM is very close to what your wanting to build.
Otherwise ... I'd avoid the M98 action, then the Rem700 ... I'd prefer the Ruger MkII. Rebuilding an M98 to feed the WSM's/RSAUM's can be tricky ... so why spend money doing it?? Rem700 magazine boxes are short and 338cal projectiles long ... so I'd avoid the Rem700 based on magazine box space. The Ruger actions are pretty good at being adapted to feed wide cases and the magazine box allows good cartridge overall lengths (not as good as an M70 though!) to be achieved. Personally I think its not worth it seeing as the 338RCM is coming ... but I almost ordered a reamer for a 35RSAUM awhile back ... so I'm not totally opposed to your idea.
Cheers...
Con

I have a 338WSM on a Savage Striker action; 17" barrel gets 2870 with 200 grain accubond and 2780 with 225gr accubond. Scott Null has the chambering reamer and did a super job. savagegunsmithing.com. Is a Savage guru but works on them all.

Incredibly precise work at very competetive prices.

338

Doing wildcats on actions that feed from a magazine that has the feed lips built into the removable magazine box is much easier than using a 98 action. Lots of folks use the 700 long action or long magnum action simply because it gives you much better bullet seating options.

Like 338CE says the Savage's are one of the simplest actions to wildcat and play with different chambering because of the simple head spacing and interchangeable bolt faces.

If you guys want to build a 35 that shoots HARD, Try a 35 Wapiti. It was developed by Larry Stephens. It is a short version of a 35 RUM. You take a 300WSM, neck up to 35 caliber. Case must be fire formed as the Wapiti is a little longer than standard WSM length. All you are going to do is move the shoulder forward a bit. It will shoot a 225grn Nosler BT at 3050fps. A lot more velosity and energy than any of the short mags. Yes, I do have a reamer for it. Try it, you'll like it.
My rifle is built on a 700 Remington with a Douglas bbl and Baker Break. Kills on both ends. Gunslinger98.

Hornedy just introduced the new RCM 338. Take a look at their specs. It might be just what your looking for.