FWIW, I’ve heard the same thing about “suction” with respect to fullers (longitudinal “grooves”) in swords. Here, it’s clearly a myth: A sword does not have fullers to reduce suction when pulling it out of a body; it has fullers because it’s like an I-beam; it allows you to decrease the weapon’s weight without making it weak, wobbly, or bendy. Perhaps both the fuller design and the myths about its blood-channeling function have been inherited from days of yore.
I've never (fortunately) had to engage in that sort of warfare hence I have absolutely no experience to speak of however; having seen a sucking chest wound from a soviet 7.62mm round - suction definitely exists within the chest cavity of someone who hasn't yet expired.
That all said, when you drive a bayonet into the body, the whole kinetic thing along with the fact the blade isn't going to go in and out at a clean (single) angle the whole suction effect is a bit of a moot point, that fucking blade's coming back out, simple as. :-)
.. I would suggest, when the blade is fitted to a rifle and it is punched into the body with the force and anger required for that form or warfare, it wouldn't matter in the slightest, but, like I say I have no direct experience from which to draw.
All I can say is that the last three major infantry rifles used by the British Forces - Lee Enfield 303, Fabrique National SLR 7.62mm and the L85A1/2/3 all had bayonets which carried grooves/channels and the instructional material associated with it's use mentioned suction.
I can't give you a source unfortunately.
Seems to me that a fuller might even do the opposite of the supposed "blood groove" function. Wouldn't adding an additional I beam kind of structure to a blade increase its surface area compared to a conventional design, causing more drag? This would be especially true if the suction issue were true. It does seem better for pulling out the blade without deforming or snapping it.
My last phase of pre deployment saw us doing bayonet training and for the mist part we got on and did it however I will confess in that some of us SNCO were a little bored. Bearing in mind this stuff is old hat to us. The younger lads were giving it large portions of gusto however one broke his bayonet in an advance, when he pulled it from the dummy he looked at it as if to say "**** that dummy just broke my bayonet" one of the instructors was balling his head off due to the damage, the lad just charged on and shoulder barged the dummy over, then repeatedly stabbed it with the stub of the blade attached to the rifle.
We cheered him on much to the distain of the staff running the course.
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Sounds like he got the essence of the lesson.