I am in the planning stages of building a (AI style) magazine fed precision rifle in .284 winchester. My objectives for this build are to engage a 10 inch target at 1000 yards on demand under field conditions, to shoot a perfect F Class score, and to kill whatever (up to deer size) that I feel the need to shoot when hunting. I chose the .284 because it is capable of meeting these requirements, and doing so with reasonable powder efficiency and recoil, 2000 rounds of barrel life, and enough energy to kill a deer size animal out to 1,000 yards, should I feel the need to do so. I will probably use 162gr AMAXs to keep costs reasonable, over a charge of RE17. This rifle needs to be as accurate as possible, and light enough for a sane person to walk around with in a mountainous environment. A folding stock would be a plus for transportation, and I'd like to keep the costs down to around $1500. I'm open to general suggestions and build ideas, however I have a couple initial concerns.

Short Vs. Long action.
loading a .284 to .308 mag length and getting just shy of 3000 fps has been done before, but why? Why not just use a long action and not worry about it, and in addition be capable of using 180 bergers should I feel the need to pay 40 cents per bullet? On the other hand, .284 bullets feed reliably out of .308 magazines with a little feed lip modification, I don't know whether or not that is true with 300 win mag magazines.

Throating.
There is a big difference in OAL between a .284 squished down to .308 magazine length and and one seated at a more normal where less of the bullet is inside the case. I noticed that McGowen advertises match grade .284 barrels in stock shipping in a week. How are these barrels throated? How about Pac-Nor's higher grade drop ins? Any other suggestions?

Stocks.
The easy button for this is to just use an accu-stock. They are accurate and bolt on bottom metal is available. In fact, the easy button for this whole build is to buy a model 10 FCP-SR, a prefit barrel, and a couple extra mags, screw them together and call it a day, or, for a long action buy a .30-06 with accustock/accustrigger, buy the drop in bottom metal made specifically for the accustock from midway, and create the same thing. Either of these options land me somewhere in the $1300 zone. The other option is to use a chasis system like the XLR etc. This would put me more around $1500 and give me a folding stock, a pistol grip, and an adjustable stock, all features I like. The only downside is that a lot of those system are made of alluminum, and I kind of like a non-metal gripping surfaces for things that may sit out in the hot sun, or the snow, with me for extended times.

Anyway, send me your thoughts and ideas. Thanks in advance.