I took a look at some of the “blower-type” BB machine guns. The $250+ “Strafer” is one of these; there were also plans for similar units grouped by operation type (i.e.,vortex, cloud, etc.). They all tend to shoot at a frustratingly non-adjustable rate of roughly 4000+ RPM, which is unfortunately (and obviously) too high for target shooting, etc. Even more unfortunately, the firing speed is somewhat related to the projectile speed in these devices. Thus, if you want a higher projectile speed you wind up with a higher firing rate (which makes things even worse). There is no concept of selective-fire/semi-auto at all; each pull blows about 20 rounds, minimum. But the worst part is that they require a tremendous amount of airflow; basically a connection to shop air is the only practical way to use these things. Connecting them to portable bulk air is also possible, and it's a great way to unload some cash if you're over-rich in the green (and then you'll quickly be back to shop air as you blow through a 20oz CO2 tank in about 30 seconds). Needless to say, that also didn't get close to cutting it for me.
I then looked into the Casleman. This was better, but the information for building the Casleman was really not sufficient, and one basically needed a reasonably well-equipped machine shop (and an equally well-equipped pocketbook) to do it. And that's why so few were ever built; I think nearly all of them by Casleman himself. In addition, you needed to cast your own projectiles for the gun, which was fine in some circumstances, but certainly not fine for high-volume everyday shooting in the yard!
The Drozd was much more in line with what I wanted. Something that I could shoot everyday that was automatic. But, several things quickly dulled the excitement. First, the stock Drozd uses 12g CO2 cartridges. Now, this has way better gas usage than a “blower-gun” but still – at the rate at which you're shooting ammo, you're pouring through cartridges like a river! So, you discover that you can adapt it to use bulk gas... Which then quickly brings us to the second thing I didn't like: You go though the expense of converting to bulk air or CO2 for just a 30 round magazine (and an extra magazine is $45, ouch!). The third depressing thing was when I found out that the Drozd is burst-mode only (mainly due to the CO2 freezing up the gun); so the fully-automatic is only sorta/kinda fully auto, and I also didn't like the stock firing rate selections. Of course, you could fix this problem by modifying the electronics in the gun; but then to take advantage of that you would need the bulk air and a bigger magazine – the latter of which which doesn't exist! Fourth, there's the noise. It's enough when you are shooting full-auto, let alone at the “it-can't-be-any-friggin-louder” level. Almost everyone, everywhere, and on every newsgroup and forum wanted to find a way to legally suppress the Drozd so they could shoot it without problem (not much luck there). Now, I don't mind some reasonable loudness, but the Drozd (like some CO2 pistols) is just too loud for many areas. Add the $300+ it would cost to get the gun and do the mods and then only have a 30 round magazine... well, it was still tempting – but, I thought I could do better if I designed one myself...
So, seeing that I was already working on alternative projectile propulsion systems, I set out to build my own version of an automatic airgun. And, I wound up actually building several. Some were super powerful large-bore autocannon type devices (which led to the powerful CX-Autocannon Series), a few were smaller-bore devices, some were very exotic designs, and another was the X177.
To give you a little history on the X177 itself, during my airgun experimentation, I set out to design something that could be replicated without any special tools or special parts. Something simple and inexpensive, yet effective. It quickly evolved into this lofty “pie-in-the-sky” concept about making and automatic airgun “for the people.” In other words, something that almost anyone could build. Something that the builder could learn from, modify, customize, and experiment with. And as I read through the forums, I realized that almost everyone wanted something like this. But, many people said it simply couldn't be done without special machining. Well, I didn't buy that reasoning, and the X177 became the fruit of that labor.
The X177 design is deceivingly simply, yet astoundingly reliable. My original X177 prototype has now fired well over 30,000 rounds with no sign of degradation. This basic, “low-power” build can fire rounds at over 400FPS and put a BB cleanly through one side of a strong steel soup can from several meters (often though both sides); aluminum cans behave as if they were tissue paper from that range. I can shoot at ranges beyond 20 meters with accuracy, even on low power fills, and can hit a Necco wafer practically every time at 10m. Selective-fire, single shot up to 1200RPM (continuously variable), it sports a range of magazine types, including super high-capacity types (200+ round magazines have been tested), and can fire all these rounds on a single, relatively low-pressure air fill. In fact, it can fire off a 60+ round magazine with a relatively low-pressure fill via a small air tank (one of my personal favorite configurations), every round surpassing 360FPS. And, it only takes a minute or two to both load the magazine and fill the tank! Not bad for something that cost about $40 in parts!
A man after my own heart!
I've emailed the guy in case he's happy to reveal what the mechanism is like.