I'll chime in. As someone who has dumped 2500$ into a factory remington setup and about to drop 2300$ on a Custom GAP Tempest barreled action, i'd say i've been where the OP is.
To answer up front about SAC, Madball they're good to go. Mark does phenomenal work. I wouldn't hesitate with going with him. Matter of fact, Mark at SAC, George at GAP, Chad at LRI, Robert at Gradous, Greg at southern precision, Mike at Tac Ops, and Terry Cross at KMW all make phenomenal rifles.
Seems you are wanting a practical/tactical type rig? Or a benchrest rig?
Either way here we go.
Caliber
If you reload i suggest 6.5x47 Lapua first, 6.5 Creedmoor second, and .260 lastly. Nothing personal against the .260 it's actually the only one i own at the moment. The crux of it is the 6.5x47 can be pushed to similar results as the .260 and 6.5CM while burning 5gr less powder and the brass lasting much longer. Also the 6.5x47L is apparently fool proof to load for as it hammers in the accuracy department. Case design is very strong, and can handle decent pressure. Downside is that Lapua is the only supplier of brass and it's currently 113$/100. Also it uses a small rifle primer and some firing pins need to bushed to keep them from piercing or cratering primers.
6.5CM is the .260 done right IMHO. The longer neck and less steep shoulder angle allows seating the long 140s to mag length without seriously taking up powder capacity. Also factory ammo is readily available with 6.5CM it's not too hard to come by. Cons are if reloading, brass is narrowed to Hornady or Norma/Nosler of which the latter two are very high priced at 1.40$ a piece. It's to note Nosler/Norma does make exceptional brass. It's to note i say norma/nosler because i do know norma does manufacture some nosler brass for sure.
.260 while suffering from seating the long 140s to mag lengh and taking up powder capacities does have a good brass selection. Lapua, nosler, norma on the expensive side and Remington on the cheap side.
Ballistically they're all pretty much equal with the 6.5x47L falling slightly and i mean just slightly behind them. All of these cartridges will do the job and do it very well.
The Action
There are the remington 700 clones Defiance, Stiller, Surgeon, etc. That all roughly are machined one piece, integral lug, integral rail, one piece bolt, side bolt release, m16 extractor, fluted bolt, bolt knobs, etc. Prices can range from 950ish to 1400$. Most of the actions you see like SAC's proprietary, GAPs (minus the tempest), Gradous, Rbros, KMW, all have Defiance build them actions to their specs. Which speaks volumes about Defiance. Stiller does the same with some gun smiths as well as having won the Crane contract for the MK13. So they directly support our snipers with their TAC300 action, speaks for them as well. Surgeon has been in the game for a while as well though i don't have any provided examples like i do for the others. Though plenty of smiths use their actions GAP and KMW come to mind. I think it's become more difficult since they sold out.
There are the three lug actions, BAT, GAP tempest, and Badger M2013. Which besides the obvious 60 degree bolt lift and three locking lugs the differences aren't just inherently noticeable. The Tempest and m2013 use a removable breech ring, i'm not sure about the BAT. Associated downsides with three lug actions are cocking. Recocking the action after a fired shot is usually tough. I know there were many complaints of the m2008, i don't or can't really find much on the m2013. In the Tempest however this issue has been addressed, if you google it it will show George lifting the action with a finger.
Then there is the latest and greatest Mausingfield developed by Ted Karagias from American Rifle Company. Which is probably the most innovation or refinement rather bolt actions have seen in a long time. Ted took the Mauser 98 action and built upon it. It's very different from the others. It has control round feed, mauser claw extractor, springfield ejector, Toroidal locking lugs, tapered key rail mount, and from what i can tell it's smooth as silk. Also love the way the extractor rotates with the round so it doesn't shave into the rim of the brass. I will own one eventually. Only issue is they're 1600$. So a bit pricey at the moment.
There is always a Tikka which will save you some money as the don't have to be trued, come with a side bolt release, sako extractor, and a good trigger. All potential upgrades you'd do to a 700. Though the recoil lug needs to be replaced IMO as well as the bolt shroud. So that's some added expense. Downsides are you can't buy the action direct, they come in long action only, and Tikka is about to stop production of the T3. The way they use the actions for short action cartridges is a longer bolt stop to shorten the length of travel when cycling the bolt. If you can find a good deal on one say 425$ it's not a bad route to go. Tikkas also have a 70 degree bolt lift. Not quite 60 but not 90 like the 700/clones.
Then there is remington. Which you can use. All that really needs to be done is truing and then barrel it. 95% of people can't shoot the difference between a properly barreled 700 and a custom. Having said that some of the upgrades are desirable and resale value sucks for remingtons. Though you can get a blueprinted/trued one from PTG for about 550$
Barrel
Pick which ever you can find in stock, as long as the proper smith installs it you'll be fine.
Bartlein
Krieger
Rock Creek
Obermeyer
Broughton
Brux
Hart
Hawk Hill
etc. the list goes on.
Stock/Chassis
I went with a McMillan A5 for my build, nonadjustable ran me 700-750ish, 300$ bedding job, 400$ inlet job, so it came out pretty expensive. Manners the other big player in the stocks has a minichassis that you can use that comes with DBM that will save you money.
Chassis' which are what i'm going with on my Tempest build (specifically KRG Whiskey 3) are a little cheaper.
KRG
McCree
XLR
All make quality adjustable chassis'.
Optics
This is where i will differ some. I understand wanting to go with some great glass to start off. I started with a USO SN-3 and i do love it. Recently owned a Leupold mark 6, which i traded for a Bushnell ERS. I also own a Razor Gen II FWIW. I will say for the money the Bushnell HDMR, ERS, or XRS are hard to beat. The glass is very very clear, feature rich just like most 2000+ scopes, and from what i have seen they're dead on when it comes to tracking. Something i couldn't say for my 1700$ Mark 6. Which coincidentally was 6/10ths of a mil off at 10 mils at 100yds. Having owned and currently owning some premium glass i will say the ERS isn't really short coming at all. Don't get me wrong it isn't 2500$ glass but it is clearer than my Mark 4 M2 on my MK12. There is also the added fact that the used market is ridiculous for these scopes. You can get an ERS at 1050-1300$ on the used classfields at Snipershide. Second recommendation would be a vortex Gen I Razor, while they don't make them anymore Vortex has the best warranty in the business. You can find them used for 1300ish.
If you have any more questions feel free to pm me. Also here is a good read on getting started into LR shooting.
http://demigodllc.com/articles/practical-long-range-rifle-shooting-equipment/
This is just kinda thought poured out on post, i'm definitely missing things here and there so i apologize in advance. It's late and i'm tired.
