Actually, I'm not entirely sure it's really a knife column, either. You see, this is the Guard Father Spike OTF. And you'd have to be very charitable to call it a "knife." That's because it hasn't got an edge.
It's completely round in cross section and from a couple of feet away looks like it might be the world's most bodacious tire gauge. But peering down the barrel of it you can see that what it does...
...Is this.
It's billed as an automatic ice pick. The potential applications for such an object are, naturally, left as an exercise for the reader's imagination.
At its core is a slightly over quarter inch thick (0.257"), 3-7/16" long stainless steel spike. The whole thing is just about 5-7/8" long retracted, 9-1/4" fully extended, and it rings in at 63.3 grams or 2.23 ounces. And the end of course terminates in a vicious point.
The fire button lives in the track where the pocket clip goes, and you can rotate the clip...
...To cover over the button and act as a rudimentary safety.
You'll probably feel a little more comfortable for that, and also knowing that the button takes a committed mashing to set the thing off. This is a good thing because the Guard Father is a single action out-the-front mechanism, which means it's just raring to go under powerful spring tension at all times. Cry havoc and the dogs of war are slipped in a hurry; when you press the button the spike fires out with extreme alacrity. And it locks in the forward position ready to serve as, just for sake of example, the world's manliest leather awl.
But! There is no mechanism for retraction like your standard issue Greaser switchblade. The only means of putting it away again is to hold the button down and manually push that pointy pokey tip back into the barrel. I highly advise not using your fingers for this, not only for the fact that doing so is functionally impossible but also a highly fraught undertaking. Instead, it's best done by pressing the point against a sturdy object but preferably one that's slightly softer than the steel is so you don't mar the point any more than it already comes from the factory.
Presumably because of this aspect, the point actually isn't quite needle sharp but arrives with a small but perceptible flat spot on the very end.
The mechanically initiated among you may have already guessed that if you have to shove the point back in by pressing it against something but still have it lock, it'd be impossible to get it completely enshrouded by the barrel without using a pusher small enough to fit inside. And since that's not how it works, you'd be exactly right. A small amount of the point is always left sticking out.
How much? Precisely 0.064", or 1.64 mm, which translates to, "exactly enough to be mildly dangerous at all times, and sufficient to draw blood if you press your fingertip against it too hard." So unless you need a drop for your next diabetic test strip, maybe don't do that.
The Guard Father Spike is not much bigger than a beefy pen or marker and it even has a clip, so the temptation to carry it in your shirt pocket immediately presents itself. The trouble with that is, with the point peeking out like that all the time it's not only immediately obvious what it is, but it'll also be at risk of raking across your shirt fabric -- or you -- at all times. Tip down carry is not an option but again, knowing all of the above, maybe that wouldn't be a great idea anyway.
Someone truly dedicated could at least probably fix the stick-out issue by reprofiling the point so it sits flush when retracted, and then devise some sort of inverse cone shaped dingus to use as a pusher tool to safely stow the spike away. Possibly with the aid of a 3D printer or something. I'm sure I can think of somebody who could do that if I thought about it long enough.
The Inevitable Conclusion
I haven't consulted a lawyer on this or anything, but I also have to wonder if this will be technically legal to carry in locales that think they've banned automatic knives but haven't worded their laws quite cleverly enough to also encompass this.
The product blurb calls the possibilities for this device "endless," but I submit to you that is only so if you have a vivid imagination and infinite patience for making up new descriptions for "stabbing things." This may fill an invaluable niche if you are, say, Fox Mulder or Agent 47. For the rest of us, though, probably not.
But it sure looks mean as hell, and I'll bet you none of your friends have anything in their collections quite like this.
If you have access to a lathe to begin with, this thing is pretty much Baby's First Lathe Weapon Project. I imagine you could turn one of these out quite easily if you didn't particularly care about the dimensions, and the only thing you wouldn't be able to produce using nothing but the lathe would probably be the pocket clip.
I haven't taken mine apart because I strongly suspect that wherever the threaded junction is holding the nose onto the body is actually located is also quite firmly glued in place. But it's just a rod with two grooves in it, a point on one end, a coil spring behind it, a tube with a hole for the button, and the button's just a rod with a short leaf spring through it that you could probably reproduce out of a slice of an old feeler gauge or something.