Call it a fuller or indents or channels or flukes or dimples or bohi (Japanese) or what it really is a cannelure...A central fuller is different then the fuller I was referring to…A fuller is usually a groove(s) or risers a raised section(s) down the centre of the blade, for strength and lightness…Used to strengthen the blade, to stiffen the blade and to lighten the blade sure, absolutely, no question whatsoever, 100% in agreement...I’m sorry in calling it a blood groove (but it was all that came to mind when I wrote it) and perpetuating the myth…Which myth? The blood channel or the blade getting stuck? The first I have no knowledge of and the latter, although not first hand, the next best thing to it, forty uncles and great uncles, cousins and nephews I think…
As to the vacuum effect, unfortunately I've never experienced it first hand as I've never had to bayonet anyone, stab them with a knife yes, bayonet on the end of a rifle, no! Some of my relatives, on the other hand have! We have had members serving the British crown, taken the King’s shilling, from Redcoats in the F&I War and as Green and Redcoats in the Rev War (we were kicked out of the Colonies to Upper Canada for being Royalists), 1812-14, Crimea, India, Zululand, Boer 1 & 2, WW1, WW2 and lastly Korea and almost all did experience vacuum sucking the blade...We have this from their memoirs (those that could write) passed down through the centuries (and now located in the Museums in Ottawa, Chicago, Smithsonian, Manitoba and in unit museum collections in Great Britain) and of course word of mouth from surviving family members and their (now mostly late) friends...Most of the WW1 guys died when I was young but a good number lasted into my teens (1960s & 70s) and we'd all listen to their stories at family functions--especially Remembrance Day or whatever you call it, Nov. 11th...
The opening to allow air to escape, erroneously, but commonly, called a blood groove is that small indentation (a fuller actually) just below the spine of the blade, usually a forte (strong section) et pre le (and before the) ricasso, and seen best on the likes of USMC Fighting Knives by Ka-Bar or the Marble’s Camp Blade series…The theory behind it’s usage and development is told by too many service men/instructors, martial artists, knife makers et al over the years from the time of Frederick the Great to the present day so I'll have to take then at their word...
They did lots of bayonet work in the trenches in WW1…We were told that this vacuum phenomenon was created mostly when the bayonet (or knife) was rammed with great force in the Hun’s body, say after seeing the SOB kill a friend of yours and if you didn’t twist the blade when ramming it, it would get stuck and be hard to very hard to extract…Sometimes they had to shoot a round into the body to break the “air pocket” so it would release…I’ve read and heard of other incidents where the blade was in the stomach and the Tommy would be jumping up and down on the dead (sometimes) soldier’s stomach, yanking at the rifle and screaming expletives while trying to free it…Had it been into the rib cage and got stuck between the ribs or pushed hard into a bone that’s a different matter altogether and there is no saying that the blade didn’t get stuck in the spinal column when rammed home…
The relaters of these incidents, and many, many more, were my family and of course the NCOs when I was in the service who have also then perpetuate this "myth" of vacuum under a stab and the reason for the twist before removal and the erroneous purpose of the flukes...If you want to call my great uncle, a retired RSM--Regimental Sergeant Major--a liar for telling me the vacuum/groove theory go ahead cause I sure the Hell won't and he's ninety seven (Tues just past) and he got it not from hand me down stories from his ancestors (which they probably did) but the British Army Training Manual, c.1943 and having his blade stick in I think three or four Japanese during WW2 before and after he was captured and sent to a work camp alà “Bridge on the River Kwai”...
Of course the bayonets (originally baïonnette, from Bayonne, France) were derived from swords as most big knives did from medieval to Renaissance times -- then rapiers became more prominent and the triangular blade was in its heyday...How many big knives derived from cut back swords have you ever seen in major European Arms or Castle Museums, me personally, a few hundred, as they would not throw away a very expensive and still usable, albeit shorter, implement that with a bit of grinding/shaping is a new knife with a sword’s hilt...
The manual of arms for bayonet fighting, blade detached, is almost like a sword fighting manual as you do have a short sword (16” to 24”) there so the moves should be appropriate…With bayonet attached there is hardly any difference from the 1720s manual of arms, 1810 manual, 1870s manual and to the 1943 manual except for some new equipment added to the frog and bayonet—like a slip ring/socket and barrel ring, nomenclature that had changed over the years due to technological advancements but stab, recover, parry lunge are all the same…
During the F+I War the shoulder strap would hold the plug bayonet and a hanger (short enlisted man's sword) and light companies like Rogers may have carried a tomahawk there instead of the hanger...
Go back to the Napoleonic War and the introduction of the Baker Rifle, which was quite short so they took an old short sword (hanger) and put a slotted sleeve on the quillion and voila a bayonet that was a short sword as well and brought the length to almost that of a Bessie with pig sticker attached...
It has been remarked by numerous surgeons during many different conflicts that they hardly, if ever, treated bayonet victims...Then again they only cared for those they could save, usually gun shot or sabre wounds and based their findings on that as they didn't do body retrieval and noting the method of demise!