Originally Posted by cavtrooper94
I'm looking to load the 225 TTSX in my 338 WM using H4350. When I talked to Barnes they recommended loading .050 off the lands. I used a Stoney OAL gauge to measure 3.473. Minus the.050 that makes 3.423, but my manuals say the maximum COAL for the 338 WM is 3.340. Any recommendations on what OAL I should use.
Max COAL in your loading manual comes from the SAMMI specification that is used to ensure that ammo will fit in and feed easily and safely in all factory rifles.
COAL in your loading guide and in the SAMMI spec is also based on the overall length from case head to bullet tip rather than the ogive.
While seating bullets shallow or deep affects containment and hence, pressures, you should use the measurement for your rifle as you have done. But, you simply need to back down from the max load and work up safely for your rifle.
If the desired seating depth that you've come up with means that the loaded cartridge doesn't fit your magazine, then you will either need to (a) use it as a single shot, (b) find a seating depth that your rifle likes which allows the cartridge to fit in the mag well, or (c) investigate magazine modifications that allow for longer cartridges.