I don’t ever “review” airsoft guns, because frankly, I don’t really care how they shoot out of the box; I’m just going to open them up and make them better anyway. What I do enjoy is diagnosing the internals of a gun and determining what they have the capability of doing. The gearbox is really where the beefy stuff is; if you want to know what the outside is like, go to a shop and hold one and see for yourself. I’m not going to waste my time by trying to describe it to you. Below is the analysis of the Classic Army SR25 internals, which I hope will answer some questions and give some insight.
Gearbox:
(I understand that there is at least one company other than Classic Army that makes an SR25; I cannot say whether or not this list can speak for other brands.)
Gearbox shell: Proprietary. A lot of people have been calling the SR25 gearbox a “long version 2,” which is an incredibly inaccurate description. Not only is it not shaped the same as a V2 gearbox, there are less V2 compatible parts in it than an M249. It is impossible to fit an SR25 gearbox into an M4 lower or upper together or individually because it is shaped differently from front to back. However, they do have resemblance to each other. Like a CA V2 gearbox, it has reinforcement around the gears area. The front end is not any more reinforced than a V2.
-Cylinder head: Standard V2 cylinder head.
-Nozzle: Surprisingly, not an M4 nozzle. You’d think so because the hop-up unit is the same, but I guess the cylinder head must sit back farther because it is quite a bit longer. The CA nozzle appears to be the diameter of a bore-up nozzle, which is actually quite stupid, because it’s not a bore-up cylinder head, so the nozzle wobbles all over the place.
-Cylinder: Longer than standard. The entire gearbox is designed specifically around the cylinder being longer so that it can output more air to accommodate longer barrels. It APPEARS to be the same cylinder as used in the PSG-1, but that is just at a glance. I did not compare them side-by-side.
-Piston head: Standard type piston head used in almost all AEG’s.
-Piston: Proprietary type. It looks much like a standard piston, but is longer and has 3 extra teeth so that it can be pulled back to the length of the cylinder. Made from the same material as other CA piston's, which is pretty decent.
-Gearbox Spring: Uses standard springs, BUT they do NOT bring the same results as used in other gearboxes. Since the gearbox is longer, the spring will never become as compressed. To give an example, an M120 spring is going to bring about the same results as about an M100 spring in a V2 gearbox. Use tighter springs than you would normally use.
-Spring guide: Standard V2 spring guide.
-Sector gear: Proprietary type. Looks exactly like a standard one, but has 3 extra teeth to pull back the longer piston. Other than that, same build and material as a standard CA gear.
-Spur gear and bevel gear: Standard type.
-Bushings: 7mm metal bushings.
-Tappet plate: Proprietary type. It is longer because the gearbox is longer.
-Selector plate, cut-off lever, wiring harness, trigger, trigger switch, safety latch, and anti-reversal latch are all the same as used in an M4/M16.
Other parts:
-Motor: Long type.
-Barrel: Standard AEG barrel
-Hop-up unit: Standard M4 hop-up
-Magazines: Proprietary
-Barrel thread: Standard 14mm CC
Battery and wiring:
The same as any other AR variant. Comes wired to the back, but could be wired to the front just as easily as an M4. Full stock can fit as much as a 9.6v Sub-C pack. The wiring is CA’s typical 16AWG, and all solder points seem to be clean and unexposed.
Air-seal:
7/10. A wobbly nozzle doesn’t help much, nor does the M4 hop-up design, but surprisingly still seals up decently well.
Noticeable flaws:
Only the seemingly mismatched nozzle seems to be a flaw in the gun’s manufacturing. Overall: a well-built, well-designed gun.
Conclusion:
As mentioned above, the point of the SR25’s gearbox design is the effective use of a longer cylinder, which creates more air-flow to accommodate longer barrels. Based on my diagnosis of the gearbox, it seams to be a very effective system for barrels exceeding 500mm. If you buy one with the intent of using a barrel shorter than that, you’re just getting an M4 that has bigger magazines and uses a bunch of proprietary parts. The SR25 is a great long-range AEG alternative to designs like the PSG-1, and it’s going to cost you much less to upgrade.
Sorry no pictures; maybe some time in the future. If you want me to make an analysis of any other guns, feel free to PM me.
-BATMAN
