Are the wood for the 870 express and the 870
Wingmaster the same. Does it mater if it is a magnum or 2 3/4 .

Half of you question is yes, the other half is no. The only difference is the quality of the wood and the finish. The one exception might be a forearm for a light contour barrel might need to be inleted a tiny bit for a standard barrel.

Thanks I have a Magnum reciever and want to have a Tarhunt slug gun built. but I needed some wood so I can get a set cheap.They use their own barrel that is perment.

Hold on thar!

The original 20 gauge 870's used a slightly larger receiver (and larger diameter barrel shank) than the current production. I'm not sure when the changeover occured, but there is a measurable difference and the barrels for one are not interchageable with the other. Take this into account.

I suspect that the wood for the old larger-frame would interchange with wood for the newer smaller frame, but I'm not certain about that. Be aware that Express wood is very plain stained Birch, while wood for the 870 Wingmaster is walnut.

The original 20 ga was built on a 12 gauge frame. The change came with the 20ga LWT the frame is smaller and while the 12 ga wood could be cut down to fit it would be better to purchase the correct wood.
My answer was in reference to 12 gauge guns, I should have clarified that in my answer.
The barrels from a 20 ga LWT will not intercange with the 20ga built on the 12 gauge frame.