Remington 700s can be somewhat problematic to take apart without the proper tools. Like just about any other firearm ever made.
First, you need the proper wrench for the action. This wrench will have a hole for a bolt that will hold the cylindrical action and keep it from twisting and getting marred in the action wrench. Do not use an action wrench that looks like it is supposed to just fit inside the rails and you yank on it, they are an excellent way to ruin an action.
Second, you need barrel blocks that fit the barrel. Remington barrels are tapered from the receiver forward, so there is no cylindrical part to grab. Best way to grab a Remington barrel is to make the blocks fit the barrel. I know, bummer, you can't just wing it.
Third, you need a barrel vise that will clamp tightly, Remington threads are put in place and a gap filling compound is put on them to make sure they stay tight. Kind of like Loctite, only cheaper, I'm sure.
And lastly, you will need to heat the barrel up a little, then crank it loose while it is hot. Put a torch on the chamber area of the barrel, let it heat up quite a bit, then crack it off.
Eezy cheezy.
