MontanaCreekHunter,
I don't have a Whelen so I have no dog in this fight.
Twist rate is all about length. Not enough is disastrous, but too much has downsides also.
If the 225gr TSX is about the same length as a conventional 250gr flat base spitzer, then 1 in 16" will do. However, I would recommend 1 in 14" for the flexibility of changing your mind later and using some of the very long, heavy for caliber bullets that are available.
1 in 12" in too much of a good thing. Unnecessary even for the longest available bullets and there are downsides to too fast rifling:
higher pressures restricting max velocity before max safe pressure is reached
faster bore wear
faster/increased jacket metal fouling
slightly less accuracy due to greater effect when bullet center of mass and center of form aren't exactly coincident (which is most of the time with standard production bullets).
Due to the large bore volume compared to the case volume, even very short barrels like 16.5" will be fairly efficient in a .35 Whelen. However, short barreled rifles are fine off the bench, but handle like a club when shot offhand. I would recommend a standard 22" to 24" barrel length for better handling when shooting under hunting conditions.
Last edited by Brazos_Jack; 11/02/10.
