Calling the Kel-Tec SU-16C the ultimate prepper rifle is like calling a Leatherman the ultimate hand tool; I suppose you could drive a nail with a Leatherman, but it is certainly not the right tool for the job. In the same way there are tasks that are less well-suited to the SU-16C. If I was hunting squirrels for dinner, I would much prefer a .22 rifle and scope. If someone was breaking through my front door, they would be more likely to face a 12-gauge pump shotgun loaded with 00 buckshot. If I had to take down a zombie at 300 yards, it would be better accomplished with a good bolt action .308. Even certain combinations of tasks could be better accomplished with a different firearm; if I needed a semi-automatic battle rifle that was also able to take that zombie at long range, I would likely choose an AR-10, like the Smith and Wesson M&P 10.
However, if we approach the question in a different manner by asking “if I could only have one long gun…”, the answers begin to change. I would want an effective defensive caliber that is capable both up close and at a distance. I would want a long gun that is highly portable– light-weight and compact. I would want the accompanying ammunition to have a good ratio of size/weight to stopping power. As I am not rich, I would want a gun that is not prohibitively expensive, yet it must also be durable and reliable.
Some may question the premise, because we plan and expect to have multiple firearms at our disposal so that we can choose the best “tool” for the job. Nevertheless, we also plan for the eventuality that we must “bug out”, “get home”, or otherwise travel to or from our weapons stash, including the possibility that we must travel on foot or, at least, with no more than we can personally carry. Much as I would like to have a .22 rifle and a 12-gauge shotgun and a bolt-action .308 and/or an M&P 10 along with an abundant supply of ammunition for each, this may not be feasible, which brings me back to the original premise: if I could only have one long gun, a strong argument can be made that it should be a Kel Tec SU-16C. Consider some of the qualifications of this particular firearm:
Caliber
While there are many who swear by their Ruger 10/22 (or similarly reliable .22 semi-automatic rifle) and while these firearms have some very clear advantages, they have one serious, disqualifying disadvantage: the .22 long rifle cartridge is not a reliable man-stopper. That is not to suggest that they cannot be lethal (I certainly would not want to be shot by one), particularly when the shot is carefully placed and followed up by many more. However, the .22 long rifle cartridge simply does not have the range or the penetrating power of a center-fire cartridge.
Meanwhile, there are those who are devoted to their shotguns. While they are an awesome and effective up close weapon, they are not designed to project beyond 50 yards.
The 5.56/.223 caliber is an effective defensive caliber with considerably more power than a .22 and considerably more range than a shotgun. Numerous battle rifles exist in these calibers because they work; they have the range and the penetrating power to effectively engage an enemy up close or at a distance.
Weight
Of course, if we are concerned with stopping power, why limit ourselves to 5.56/.223? Why not choose a .308 battle rifle? The .308 has considerably more range, penetration, and stopping power. Fortunately for us the U.S. military has already addressed this question. The .308 round is nearly twice the size/weight of the 5.56/.223 round. In other words, we can carry twice the number of 5.56/.223 rounds for the same weight/size. If it becomes necessary to take only what we can carry (possibly on foot), this becomes a huge consideration. I would rather have 300 rounds of 5.56/.223 than 150 rounds of .308.
This consideration becomes even more significant when considering the rifle itself. You would be hard-pressed to find a center-fire, semi-automatic rifle to match the sub-five-pound weight of the SU-16C. I very much like my Ruger Mini-14, but it is several pounds heavier. Apart from the extra weight of the steel magazines; the SU-16C is entirely comfortable with polymer AR-15 magazines. If I was required to travel on foot, those extra pounds would become a serious issue. The same may be said of virtually any other long gun, including anything remotely resembling a battle rifle– AR-15, AR-10, AK-47 (not to mention the wonderful but extremely heavy classic battle rifles and their modern variants like the SOCOM). If there is a semi-automatic center-fire rifle and 300 rounds of ammunition that weighs less than the SU-16C while retaining (at least) the range and power of the 5.56/.223 cartridge, I am not aware of it.
Size
While AR-15-style rifles commonly have collapsible stocks to reduce their overall length, the mechanism of the AR-15 makes a folding stock impossible. The SU-16C has a true folding stock that reduces to a total length of approximately 26 inches, which is small enough to conceal in many backpacks. This could become a decided advantage if circumstances dictate stealth. While most of the SU-16 models have a folding stock, the C model folds to the smallest overall package and is the only model that may be fired while folded.
Durability/Reliability
While initially having the appearance of a somewhat cheaply-made gun, numerous reviews and YouTube videos bear testament to the durability and reliability of the SU-16C. I purchased a used SU-16C with 1500 rounds of ammunition through it already, yet it has functioned flawlessly after another several hundred rounds. Owners quickly discover that, while not an elegant firearm, it has been designed and manufactured for reliable utility.
Cost
A new SU-16C retails for $779, however, your street price may vary. Regardless, it is likely to be comparable to an entry level AR-15, a typical AK-47, or a used Mini-14. My used SU-16C set me back $500. As the previous owner had secretly longed for an AR-15 for some time before actually getting one, he had attempted to convert the SU-16 to a pseudo AR-15 with a replacement stock/adaptor and fore end. I immediately re-installed the original stock but kept the AR-style fore end (although the stock fore end adds some utility, as it can be deployed as a bipod). Add a few inexpensive 30 round PMags and I have a reliable, effective semi-automatic rifle for $550.
So what is wrong with the SU-16C? There is just one thing as far as I can tell; they are difficult to obtain, due to very limited supply. Kel Tec does not have dealers. Instead, virtually any dealer can order one through a distributor who, invariably, does not have one in stock. I was on a waiting list at my favorite gun shop for a month before finding one on the used market. Apart from this, I would be hard-pressed to think of one thing about which I am dissatisfied.
There is typically only one additional decision to be made with respect to an SU-16C, and that is sights/optics. I have found the stock iron sights (rear peep and front AR-style post) to be surprisingly effective despite my aging eyes. I am deadly at 50 yards and dangerous to 100 yards. However, the sight rail molded into the frame of the SU-16C allows easy attachment of optics such as the inexpensive but highly regarded TRS-25 red-dot or my personal favorite– a low-power variable scope with illuminated reticle. I am confident suitable optics would make me deadly to 100 yards and dangerous to 200.
Let the debate begin. A strong case may be made for a Ruger 10/22, an AK-47, a Mini-14, or a short-barreled shotgun. (Any of these may be equipped with a folding stock to reduce size when needed.) Others will swear by their AR-15, AR-10, M1A, et cetera. However, if I could only take what I can carry, I would add a handgun (either a substantial center fire caliber like 9 mm or .40 S&W for concealed personal protection, or an accurate .22 for use in hunting small game) to my SU-16C and stack that configuration against any other combination for weight, size, versatility, reliability, and firepower at a modest cost.