Welcome to the board K Hini. I've found that my .223 is pretty immune to OAL changes, however that's in my rifle. The safest way to test it in your gun is "start at a lower charge and work up." You'll hear that phrase A LOT in reloading. If in doubt start low and work up.
In my 22-250, if I load to the recommended OAL for the 40gr V-Max, the bullet will drop into the case with just a little pressure. To remedy this, I need to load longer than recommeded OAL. Loading .050"-.100" longer didn't effect pressures at all from what I can tell.
I think, and somebody please correct me if I'm wrong, but loading longer will only decrease pressures. You need to worry more when you shorten the OAL.
