This is a great forum.....

Any how, I am considering taking an old Model 700 in 270Win and converting it to 338-06AI 26" barrel. I have planned on taking 35 Whelen brass and sizing it down. I am looking at a Redding 3-die set.

The questions are:

1. Do I have to fireform even with the full length sizing die?
1a. If I have to fireform, what's a good fireforming load for it?
2. Are there feeding problems with the AI? Feeding probs with a neck sized case?

Since this will be primarily used for whitetail, I have planned on using 225gr bullets. I am open to powder suggestions. I was thinking Reloader 15 would be good.

Thanks in advance for the help!

1.-Yes
2.-Max 338-06 loads
3.- Maybe. Sometimes they feed fine, sometimes you have to do a little rail/magazine lip work.

Hope this helps. - Dan

wpm,
Yes, fireforming is a must. I suggest you only use new cases rather than previously fired ones.
Dan's use of max loads also means using jacketed bullets. That's too expensive for me, cause even though they fit the chamber at this stage, they're not accurate enough for hunting. My gunsmith said to use about 10 grains of Bullseye, fill the case to the neck with cornmeal and stuff in alittle pillow ticking to hold all in place. Hold the muzzle to the sky and fire. That worked OK but it doesn't keep the case against the boltface when the firing pin hits the primer. I called the Sierra bullets hotline and got some hints from one of their techs. My new way leaves a perfectly formed case ready to use with any accurate deer load.
I bought a Lee lead bullet mold in .338 caliber. It's 220 grains. I cast them out of wheelweights, and tumble them in liquid Alox.
I use CCI 200 primers, 28.3 grains of SR4759 powder and seat that lead bullet out far enough to
hit the rifling--which is pretty long in my gun as it's throated for the 250 grain Nosler partition. The case stays up against the boltface and the shoulder gets perfectly formed all in one go. Sometime in the future I'd like to perfect a cast bullet load to use in the field. Loading your own ammo is one thing, making your own bullets is like icing on the cake!
RL-15 is good, so is IMR4320. I'm working up a load using VV N550 with a Barnes 'X' FB at 225 grains. So far 2565 fps with a 10 round extreme spread of 20 fps at 58 degrees F. in a 24" barrel.
My Rem 700 started out as a 25-06. As far a I know there wasn't anything done to the feed rails. It feeds slicker than, well you know what.
I haven't used 225 grain bullets on deer cause 200 Speer soft points tear them up pretty well.
Hope this helps.