I want to have a rifle put together starting with a Remington 700.
Due to Italian law I cannot change the fundamental factory specs of the rifle so;

I want a .300 win mag with a 26" barrel.
That means I have to start by buying a complete rifle, and re-assemble it maintaining the same barrel length and caliber but I can change the barrel profile, trigger, stock etc...

Tha plan is to get the rifle into a McMillan Lazzeroni thumbhole sporter stock (pillar bedded) and that it shoot sub, preferably 1/2 MOA. I have a BR smith who can blueprint the action and will install a new barrel if needed. The trigger will either be replaced or the factory trigger tuned.

The cheapest option seems to be the Sps at €781 (there isn't much of a second hand market here)
The XCR is also appealing for the special coating but are there aftermarket coatings availiable? It retails for almost double the Sps so maybe it's not worth it unless someone can tell me NiTrite the finish is kryptonite proof.
The 700 "Police" (I don't know what it's called in the US) is also appealing because the action is teflon coated but matches the XCR in price.
The Sendero is stainless and supposedly very accurate out of the box, potentially eliminating the need to blueprint the action? It cost the most of the three but is a fairly popular rifle and there is a chance of finding a second hand one.

This confusion on which model to start with stems from the question; Are all the Rem 700 actions the same?
From the Sendero to the XCR to the Sps are they all the same action just differently coated/blued or stainless?

I am undecided on the magazine configuration, detatchable or blind. Does the blind mag make for a stiffer stock and more potential for accuracy? Having no magazine to lose it a nice thing too.
I don't like the Remington DM's but have seen aftermarket bottom metal with a detatchable mag like the ones from HS Precision. Who makes a cheaper bottom metal than HS?

Thanks in advance for any help, I have a bit of time before I start and McMillan has said they have an 18 to 20 week turnaround at the moment so I guess there is no real hurry!

EXPRESS, I will try to answer your question as best I can. The Remington 700 action is available in a long & short action. You will need a long action with a magnum bolt face to build a 300 Win Mag. You did not mention what barrel contour you wanted, but from your description I would venture to guess that a 700PSS (Police) might be what you are looking for. This rifle is availvable in 300 Win mag & may help keep the cost of the project down, even though it is more expensive initially. As far as the detachable mag is concerned, I don't think that there would be much difference in rigidity between the hinged floor plate & the detachable mag. You will still have a big hole in the bottom of the action.
I hope that this is helpful.

hvy, I think I'll go with the detatchable mag. Cabelas offers the Kwik Klip kit for less than half the cost of the HS Precision bottom metal and it looks to be identical for all intended purposes.

The barrel contour will probably be a lightweight varmint, #5 from Shilen or their sporter magnum, which is lighter by a few ounces.

This rifle is for hunting but should also serve for long range plinking and hunting too.
I'm going for a setup that is comfortable enough to sit and shoot through a range session but light enough to effectively carry when hunting. I might go for a mercury recoil reducer that I can slip in and out for load development but I don't know how much hassle that might involve with removing the recoil pad each time.

As to the action, like I said, my hands are tied so I have to start with a complete rifle, already chambered in .300wm with a 26" barrel and effectively re-build it with new parts.
Hopefully I'll find a second hand rifle otherwise I'll have to order a new 700, the Sps is the sheapest facotry offering.

Another consideration I might need to make is the length of the magazine, ejection/loading port and the little feed ramp to accomodate longer COL handloads, a porblem I have encountered with many factory rifles.

Any suggestions?

EXPRESS, without looking it up I don't know the barrel length on the SPS, but it would be the cheapest route. You might be able to sell the parts you don't use. I know that the bottom metal brings a decent price here & the stock off of a PSS will sell for a good price also.
I don't know how to answer your question about the magazine. It seems to me that you would have to discuss how the chamber & throat is cut with your gunsmith. You might need to load a dummy round with the primary bullet you want to use, that will fit & feed from the magazine. The smith may be able to use this to cut the chamber the way you need it.