Out of these two rifles, which would you choose?

"you want full powered rifles "

The **** are you talking about? Both of those rifles are civilian versions, and what rationale do you have to support your 'full powered' vs what idea?

" Sig SSG 3000 patrol upgraded to a McMillan stock vs. Remington 700 Target Tactical? "

Well, since they are both < 0.5MOA guns with similar velocity profiles (Sigs are known to have fast barrels, but the 700 has 2" more length), one probably won't shoot better than the other.

Next up on my list is cost, weight, and condition. You know what condition your Sig is in, you only have an idea about the condition of the 700 unless you did a careful inspection and looked at it through a bore scope.

In theory, they cost the same (I don't know exactly what the deal is and what you paid for yours).

As for weight, the stock SIG 3000 and the 700 are within 1/4 lb of each other, so that shouldn't matter, but IDK how much the McMillan stock will change the weight of the SIG.

In the end, it sounds like you really aren't gaining anything with the 700 except you will have it faster and already set up (no fitting or anything) but you won't have as good of an idea about condition.

If I was in your place, I'd keep what I had.

You are not "building" anything. Putting a commercial stock on a commercial is not building it.

Changing the stock does not change the range of the rifle.

I seriously doubt that you are up to the accuracy of either of those rifles off the shelf. Changing the stock will not make you a better shooter, nor do I necessarily think they are improvement over what the specific models have off the shelf.

While the M700 Target Tactical is an excellent rifle, you are deluded if you think that simply changing the stock will make it a civilian version of an M40. The M40 is a weapon SYSTEM, which includes a custom action, custom tuning, and custom and 24" barrel, and a Schmidt & Bender 3–12× 50mm Police Marksman II scope.

Trade a Sig SSG 3000 for a Rem 700 Target Tactical after 3 months ago you traded the Rem 700 AAC-SD for the Sig SSG 3000 patrol, I am calling it all BULLoney. My guess is that you are 15 years old and won't have enough money to purchase any of this until you are 32 and will never have the talent to use it. Who else would come to anonymous forum and ask how they should spend about $2000 on a rifle? Can you say Mall Ninja?

Invest in a reloading kit from RCBS or similar maker first;won't matter what rifle you're shooting if the ammo isn't made for it specifically. I have factory stock A-Bolts that get Sub-MOA with my handloads, and in the long run every longer range shooter is going to need to load for the rifle: you need to establish proper COL with a gauge,work your loads up and put in range time.

Rifles you might want to look at besides those are the Sako TGR 22 and CZ 750 SR

Full power depends upon the caliber that the rifle is chambered in and you can spend $5000 on a stock and it will not give the rifle any more power.

Well...in MY world, I would get the cheaper one ( guessing that's the 700, right ? )..in 338 Lapua Magnum....since that is the current world record sniper round. You should be good out to 1500 meters.

You should buy a Mosin Nagant.

And a tube of vagisil.

What is wrong what the stock it has already? Would you not rather worry about optics instead?

never get civillian versions of guns you want full powered rifles