I'm no expert but I think the Monte Carlo stock will make you shoot below the target and is especially needed in target shooting. However, depending on the fit, one can or cannot benefit from a MC stock vs a regular stock. I do notice that some of the recent BT-99 guns do NOT have a MC stock, so I don't quite know if I'm correct or not..
My M12 trap gun and my M70 rifle that I hunt with (among others) both have Monte Carlos. Pat I. is right about keeping your head upright and it's something I really prefer. Given a choice, I'll take a Monte Carlo stock, especially one in nice walnut.
MODIFIED GUN STOCK. "Something New From England Which Isn't Popular"
A representative English gun firm recently devised a new gun stock which is quite a novelty, but not likely to find favor with many sportsmen. The firm terms the new stock a "modified stock." This stock, while retaining the extreme drop at the butt, has a parallel bend along the face line from the comb to five or six inches back, giving the same alignment at any point between these limits, subject in some cases to slight modifications.
It is generally conceded that shooting is greatly improved when the stock fits easily against the face at the moment of sighting. This cannot always be obtained when the drop of the stock continuously increases from the comb to the extreme butt. As most guns used by American sportsmen have a bend of one and three-fourths inches at comb to three inches or more at butt, there is an increasing slope of about one-fourth-inch between these points. It follows that in shooting a high-flying bird the face presses against the stock nearer the comb than when aiming at a low-flying bird or ground game; therefore, according to the flight, high or low, so the sight is taken at various distances from the comb and practically increasing or diminishing the bend of the gun at each shot.
English and continental sportsmen for years have used stocks parallel from comb to butt, but the extreme drop of guns which has prevailed with American sportsmen, although there is now a tendency to use straight stocks, has interfered with, the attainment of that desideratum - easy and accurate shooting.
I have a fat face with basically no neck. I use a monte carlo stock. Years ago one of the AA shooters could not believe that I use a monte carlo stock. I told him it feels more comfortable to me than a straight stock. With this particular type stock, I see a figure 8 and it breaks targets with absolute authority. To me, if the sight picture and the gun breaks targets, and it feels comfortable, who's really to say what is the correct type of stock to use? I also like the placement of where the recoil pad is on my shoulder with the monte carlo stock compared to a straight stock when I mount the gun.
To each his own on Straight Vs Monte Carlo Stock, the one that is most comfortable, and gets you the sight picture you require w/o lifting your head when you shoot to watch the target break.
I have a hell of a time getting a stock w/enough cast off for RH shooter, I like 1/2"inch cast off.
My personal opinion is the length of your neck determines the stock, average neck to long neck a Monte Carlo stock w/ single, double, or triple Monte Carlo stock. The double Monte Carlo works best for me, what that means is the Monte Carlo is twice as high as a standard Monte Carlo.
The stock is lower on and in my shoulder pocket, and my head is more up-right.
You will need to try them out to see which is better for you.