The TaylorMade P770 irons are their forged cavity back model for better players who also want a compact blade style head.
The matt finish of the Forged 1025 Carbon Steel head gives it a classy look that mirrors the style of the P750 Tour Proto irons so that you can blend the two sets as they are very close, with the 750 having a similar style and a 2mm shorter blade length.
The mirroring continues in the cavity back of the P770 where a polished chrome strip over the top of the muscle back reflects the number back at you.
Below this wrapped around the back of the sole in the 3 to 7 irons is a Tungsten Back Bar that is there to lower the CG and increase the MOI and get the P770 launching a little higher than usual for this style of head.
In testing on GC2 with 6-irons from the P700 models, you could see that the P770 flew higher than the P750 with the same level of spin.
There is 0.5° difference in 6 iron loft with the P770 being the stronger model and then it is 1° stronger in 7 to PW
However, the real difference in distance was probably down to the lighter stock KBS Tour FLT 120 steel shaft in the P770 that averaged an extra 2mph club head speed.
The 8-iron to PW loses the tungsten, presumably because it is launching higher anyway, but I am not sure that it helps the feel much as the short irons don't quite feel as sharp as you might expect.
The wedge in particular looks quite square at address thanks to a deeper face in the heel area and is not something I am sure better players will go for.
This section of the face is deeper across the whole P770 set, but it seems to be more noticeable in the shorter irons.
The feel from the mid-irons is good and it was really these longer irons that felt and sounded the best, probably because the slightly bigger head makes better use of the cavity back design.
With the 4-iron you can also just about see the back of the cavity at address which seems unusual for a better player set of irons.
Whilst there is a progressive offset as you go through the set to make them a forgiving blade style club, it is still a pretty compact head and the combination of head size, material change and cavity back maybe does flow as well as it could through the set.
There are several competitor irons in this sector, with and without tungsten in them, which probably feel a little better and/or cost a little less, so the P770 has it's work cut out for your attention.
However if you are a TaylorMade purist playing off a low single figure handicap, then the P770 would be worth considering if you find that the P750 Tour Proto irons are a little on the small side.