A Gaboon viper is a lot like an Olympic powerlifter. He looks fat and lazy, like he spends most of his time on the couch watching TV. But all that bulk is actually pure muscle. In one explosive burst he can achieve unbelievable feats of strength and speed. Evolution did some pretty cool stuff with Bitis gabonica.
I would describe a really motivated Gaboon as an exploding snake grenade. Their true strike range when they decide to get serious about it is close to 100% of their body length at any angle except straight vertical or directly backwards. Then it drops slightly. That means that a hand on the tail of a Gaboon viper is not in a very safe place if the head is not physically blocked.
I have heard some people talk about being able to pet and touch their Gaboons because they are such slow, docile snakes. I have seen a number of people handle Gaboons with their hands inside what I know to be the accurate strike range of the species. I think they believe that they are doing so safely because they have never been treated to the sight of an ass over tail Gaboon explosion. If you frighten, hurt, annoy or trigger the feeding response of a Gaboon viper sufficiently, the physical response they can muster is far beyond most people's expectations.
Gaboons look and act awfully touchable. I know a number of people who have freehandled them and never been bitten....yet. I also know people who have petted or freehandled or tailed Gaboons and they have been bitten. Many of them have expressed awe and wonder at the manner in which they were bitten, because big fat slow snakes are not "supposed" to be able to perform such acrobatic feats.
I strenously discourage anyone who appears to be spreading the already too common idea that Gaboons are okay to touch and hold, or even okay to tail without a few more precautions than you would take with other species. Their physical capabilities are greater, and where a rattlesnake or a cobra cannot turn around and reach you, a Gaboon really can, and with absolutely no warning. They go from immobile to explosive in a split second; it's the way evolution designed them.
A lot of keepers don't actually know about the full physical capabilities of these animals because you could keep Gaboons for years and never see them really exert themselves if you practice good husbandry and don't stress them. I've seen some of the more extreme maneuvers only because I am doing examination and treatment of freshly imported adults, including some unbelievably stressed animals with painful injuries. Keepers who are smarter than me and stick with healthy captive born animals will hopefully never see an angry, hurt Gaboon unleashing the full acrobatic ability of this species.
If you have a nice captive animal, try playing "Gaboon football". Show the snake (from a distance and held on long forceps) a prey item of appropriate size. Wave it around a few times until you see those subtle little eye motions definitely following it. Then throw the food at the snake. The speed with which a hungry gabby can intercept your airborne pass is very educational.
I have a copy of a paper somewhere on the physics of a Gaboon strike; it was theorized and pretty well tested out that one of the reasons they have extreme fecal retention is ballast to launch some of these impressive, spring loaded, flip ass over head airborne strikes. I guarantee that if your hand is on the animal's tail and its head is not physically blocked, there is the capability of a strike even if the animal is held at 90 degrees vertical. Anyhow a lot of you probably know this already, but some people apparently don't, and they underestimate these animals badly.
The difference between handling a large black mamba and a Gaboon is that the mamba is much more likely to get acrobatic and double back on you when you are tailing it. It is also much less likely to succeed, because you can see and feel it coming in the body motion and move to block the strike or keep the snake off balance by moving your hand around. A Gaboon will rarely get motivated enough to go for a backward strike when you are tailing. But when they do, you are in extremely deep kim chee because they can go proportionally farther back than a mamba, and the strike is much faster with absolutely no warning or telegraphing in the body language. A Gaboon will probably not miss and you will not be able to block the strike. If you are in this situation you are absolutely screwed.
It is generally easier to handle Gaboons than mambas because Gaboons sit there like a bump on a log, looking at you with their big froggy eyes and doing absolutely nothing while mambas are flying all over the room and trying to perch on your head or get under the nearest piece of heavy furniture. But given the choice of having a large adult black mamba or king cobra actively going for me while I am tailing it and a Gaboon actively going for me when I am tailing it, I will take the elapid and be very, very thankful. When you do the tail dance with with elapids, it's quite normal and expected for them to turn around and have at you. That's manageable with a hook. There is absolutely nothing I could to do avoid a bite by a Gaboon viper I was tailing if it had a clear path to any part of my body. If there is not a physical block between the snake's head and the handler, your life depends entirely on what the snake chooses to do rather than on your skill. So if the snake is having a bad scale day or woke up on the wrong side of its hide box in the morning, you're nailed. Owie.
I am somewhat attached to my anatomy, as ordinary as it may be, and I would rather not have any body parts inconveniently rotting off. So I do not touch Gaboon vipers without making darned sure that their heads are restrained or their strike path is physically blocked. Their strike path is 360 degrees all the way around their bodies and they can fold themselves in half to bite the hand that is tailing them. So that's a lot to block.
Plastic tubes are a handler's best friend as it is the work of a moment to slip one over a somnolent Gaboon's head and bother the safely restrained snake at your leisure with exam and medication as needed. Gaboons are ideal candidates for the "head masking" style of tubing as depicted here. The short tube is easy to slip over the head with forceps. This effectively "disarms" the animal within seconds for easy handling. They are not particularly good candidates for tailing for the reasons outlined above. They can be tailed if the handler takes special care to position the hook to block an upwards or backwards strike. But it is much easier and safer to use other techniques to move these animals such as two hooks, the "come along" floor drag with a single hook or tongs, or head tubing.
The "come along" floor drag technique is illustrated here with tongs. The snake's body weight is supported primarily on a solid level surface, and the handler pushes or pulls the snake along gently to move it between enclosures. A Gaboon can also be gently guided with a hook to crawl into a trap box where it can be safely locked for transport or routine cage maintenance.