Originally Posted by BDL
It gives a better head position for one. It also reduces the clicks needed between longer shots.
It does however increase the clicks needed for shorter ranges.
That's it in a nutshell.
To add a tad more to that ...
Sit in a typical FT sitting position and rest your front hand on your front knee ( common position ). Now have your back and head in a relaxed and comfortable position. Now measure the vertical distance between the top of your hand ( where the rifle will rest ) and your eye ( where the scope needs to be ).
That will be quite a distance.
You now have a number of choices ...
You can have the fore end stock a normal thickness ... that will mean that you will need quite a large distance made up with a riser rail and mounts to get the scope level with your eye. You'll also need a very very high cheekpiece.
Or you can have a very very deep fore end ( added hamster ) and much less of a distance made up with riser rail and mounts. You could now have a much lower cheekpiece.
Most people will like to keep the vertical balance of the bore ( barrel ) somewhere near the centre of the distance from hand to eye. So they will usually have some added depth to the fore end and a moderate riser rail and mounts.
That's all with a comfortable back, neck and head position ( all quite vertical/upright ). Some shooters will have longer legs and so the hand to eye distance is less ... so they need less distance made up with fore end and riser rail/mounts. Some ( with average body/legs etc ) will still choose to have less distance between hand and eye and will make up for the lack of extra height in the stock/riser rail and instead will bend their back and neck over to lign up with the scope.
You pays your money ...