Adding a 6.5-284 barrel to a switch barrel/switch bolt head Specialty Pistol.
Also, moving to a magnesium chassis stock, so now, it will be a switch stock as well. Already have one in wood.
Once this arrives, I will have barrels in 25 PRC, 6.5 PRC, 25-284, and soon to be added 6.5-284.
I will...
The times I have gone above max in a load manual, is when the cartridge in question was long for the action chosen...For instance the 284 Winchester.
It was set-up in short action rifles, with the bullets seated quite deep.
Put that same cartridge in a single-shot action, with a longer throat...
There are no cons, other than you will have reduced MV compared to longer barrels
Just use the same powders you would normally use for a standard rifle length barrel of 24-26 inches.
Let's say the MV with 140's is 3000 fps with a 26" barrel.
I would guess 25 to maybe 30 fps loss per inch...
Discover the changes for yourself!
Put some of your ammo in your freezer, and then chrono it, as this will give you hard data.
Also get your ammo heated to around 70 degrees, and chrono it.
What is the difference in drop with the velocity change with your TAC load once you know the two extremes...