Not doubting you, but that seems a little counter intuitive about the bipod placement.
Why would you think that? And, I'm not trying to pick on you, just trying to understand where you're coming from. I was a machine gun repairman for Uncle Sam for a few years in the 70s, and they have always interested me, so I've got a little more experience with their designs and operation than many people, including some infantry machinegunners, who, no doubt know their service weapon well, but often don't know a lot about other guns or design principles.
First, take a look at sporting rifles, particularly varmint rifles, which are often used with a bipod. Where is the bipod mounted? NOT on the barrel, but on the stock, usually on the QD sling swivel stud. The function of those rifles is to be accurate. Mounting the bipod on the barrel works against that.
Has it been done, is it done today, yes, on military arms, where pinpoint accuracy isn't the requirement. (and also as a cheap plastic clip on for .22s) But not when accuracy is important. Even mounting a bipod on the stock can change the point of impact to a degree, but stock mounting seems to be more consistent and affects shot to shot accuracy less than barrel mounting.
With a machine gun, where the object is not to put 20 shots in a group you can cover with a quarter, but to put those 20 shots scattered over a couple square feet (and in one to two seconds) the effect of a barrel mounted bipod on accuracy is usually insignificant, because the overall design of the gun isn't all that accurate to begin with.
Browning machine guns were kind of an exception, even in their heyday, they were exceptionally well made and accurate. Remember that in the pre-WWII world, military arms were made like civilian arms. Heavy steel, made to last, and generally accurate to very accurate.
War time experience taught every nation's military some important lessons, one of which was, building quality machineguns like traditional sporting arms was a waste of money. Guns (all of them) get lost in combat /damaged /destroyed at a huge rate, they almost never survive long enough to actually wear out from use, WWII taught designers the value of guns made cheaply, which would last "long enough" and if cheap, could be easily replaced. (and note, I'm speaking primarily about infantry machine guns here.)
WWII proved the value of guns made with light metal stampings as major components. Not only were the guns lighter weight (and therefor better liked by the guys who had to carry them), but they could be made faster, and cheaper than the more traditional guns. When bullets fly, armies learned that "works good enough, and is cheap" was better than "costs more, but lasts". That lesson is still with us today, at least, when it comes to small arms.
There are several "classes" of machine guns, and some armies class the same gun different ways, depending on its intended use. Some guns cross classes, and some are kind of in a class by themselves.
The general classes are Light and Heavy, based primarily on the overall weight of the gun system, but also taking certain other features into account. Light machineguns include many belt fed and box magazine fed designs. They are intended for intermittent full auto fire. Heavy MGs are belt fed, intended for more sustained fire (many were water cooled). Caliber also plays a role in classification, as .50 /12.7mm /13mm are considered heavy machine guns, even when air cooled and built as lightly as practical.
The Germans introduced another class, just before WWII, the GPMG (general purpose MG), where the same gun (MG 34, and later MG 42) were considered a light MG when fired off the bipod, and a heavy MG when used with their tripod mount (and optical sight).
I love to talk machine guns, and will go on at length, if you don't stop me.
What do you want to know??