Re: Main reason for docking barrels?
All the cool kids are doing it.
For some cartridges it makes very little difference in performance in terms of MV, especially with the newer powders hitting the market in the last 10 years.
I have a 20, 21-1/8, and 26" 308 at my disposal. The difference in MV, all with premium, hand lapped, cut rifled barrels across the 6" span is about 40fps.
The guys doing it for a living are doing it for making the rifle handier. There's suppositions of improved accuracy, easier to find nodes, and some other things.
Considering that there are a couple of 1000yd BR World Record groups held by a 30" barreled Krieger I don't give a whole lot of creedence to the "more accurate" statement. Every time that I've looked into someone who's claimed that the rifle was "more accurate" I've found other mitigating factors. Barrel harmonics theory doesn't support the idea of "shorter, stiffer, & easier to load for"
But they shoot well, the performance drop for something of average "overbore" and expansion ratio (ie 223, 308, 6.5 Grendel, et al) do very well with shorter barrels.
The big factor to worry about in today's age of commonly found, high quality LRF and good ammo is generally NOT drop but rather wind drift and other "less scientific" effects that really bring the shooter into the equation. The wind drift of a 20" 338LM is affected, but affected in a manner such that the extended drop trade off for a handier rifle makes it tolerable.
If you're chasing speed records then a short barrel isn't the solution. If you want an all around, handy rifle for many different applications then a 20" 308 is pretty nice in my experience.
