Great to see some else is playing with the .338-06. I recently had one built on a Zastava MkX action. (I've had the rifle since 1975, killed my first deer with it in '76, in .30/06 of course.)
I too have found the H414 to be the best powder for hunting loads. I haven't shot any 225's, but have tried several 200gr and the superb Sierra 215 BTSP. My second favorite powder is RL-15.
My data and results are as follows:
200gr Hornady or Speer
Seated to 3.335" OAL (to cannulure on Hornady)
Winchester LRP
Winchester .30/06 OFB -reformed.
63.0gr H414 gave 2,868 fps. Accuracy "so-so" 1.5-2.0"-5 shots @100yds. (books suggest this is max., I concur)
62.0gr @ 2,840 ("my load"), accuracy slightly better.
54.0 Rl-15 @2,820 (books say 55.0 is max, but this is enough!, made the 2,800fps threshold I was looking for)
52.5 RL-15 @2,755 fps. Most accurate 200gr load. 3-shots @ 0.875" with Speer bullet.
Sierra 215 BTSP @ 3.315" oal
60.0gr H414 2,750fps. Duplicates A-Square/Weatherby factory load. 5shots@ 1.2" (3,611ft/lbs!)
57.5gr IMR-4350 @ 2,625fps VERY accurate, 3shots one hole (0.70").
60.0gr H-4350 @ 2,705fps 3-shots only for accuracy velocity, essentially same as H414.
52.5 RL-15. @2,720fps -also a very good load- warm though.
I might add that none of these loads showed any signs of excessive pressure. (I can't say the same for the OFB in .30/06 they were made from. -All had cratered primers and some showed head burnishing into a plunger ejector on the headstamp!)
As JimC said, the two Hodgdons powders are excellent. I plan on trying RL-19, as well as IMR-4064, and 4320. For economy and practicality, the RL-15 is probably unbeatable though.
As all my reloading manuals state, it's really hard to believe that this round has not been commercialized sooner and isn't wildly popular. Having owned and shot a .30/06 for practically my entire shooting career, I unequivically concur that the .338-06 is substantially more gun than the .30/06. Alot more than I expected! You should be able to approach 2,650 with the 225gr bullets, and 2550 with 250gr. bullets. Bear in mind that most of the factory loads I've chronographed with 250gr bullets in .338 WinMag run 2,650fps. (not my guns/ammo). I consider the comparison of the .338-06 to the .338 WinMag to be on the order of .308 WCF to the .30/06. Definitely not the order of difference of .30/06 to .300 WinMag. BTW, recoil of the .338/06 is on the same order of the .300 WinMag. (makes sense as energys are quite similar). I plan to substitute the Nosler 210 Part. for the Sierra for heavier game. Once I get the loads nailed down, I probably won't shoot this gun much, as it's really quite a bit more than necessary for deer. (I shoot those with a .257 "Bob", or a flat-top .223 with 55-60gr SP's.) The '06 was already languishing in the corner prior to the the conversion.
I hope you are pleased with yours as I am mine.
Now, If I can only get drawn for that Elk tag !!!
