I've been deliberately trying to kill this gun in order to test the longevity of the stock JG mechbox. I've done everything you're not supposed to do. I've used cheap .12g BBs with huge seams, and even reused BBs. I've dry-fired it repeatedly, and other than the occasional cleaning of the barrel, the gun has seen no maintenance whatsoever.
I plink a LOT at home, and the MP5 is always the first gun I reach for. I estimate that in the year or so that I've owned it, I've put about 45 000 rounds through it, as well as thousands of dry fires. I really wanted to know how well the mechbox would hold up to unrealistic abuse.
As a result, the box developed a crack near the nozzle on one half of the shell at about 35 000 rounds. But that didn't slow the gun down in the slightest. It didn't affect its performance in any way at all. It was still as accuract and its velocity remained constant at 330-340 fps.
A couple of weeks ago, I ordered a new Deepfire reinforced 7mm mechbox to replace the JG box. But I have this thing about picking things apart when they work. If something works fine, even if it has a break (the crack), I don't like taking them apart. And MP5s are a pain in the ass to disassemble compared to an Armalite, so I figured I would deliberately try to break the gun with dry-firing. I put in my battery, and held the trigger down, dry-firing away until the battery started going weak. Despite this abuse, I still couldn't get the damn thing to break.
So a couple of days ago, I took the dive and finally replaced the mechbox. I must say, I was MOST impressed with the state of the internals once I opened it. The gears are reinforced CA gears coated in thick brown goop that's typical of most Chinese clone guns. The shim job was about as perfect as I could have gotten it. I took the compression parts out and closed the shell back up. The gears had no side-to-side play and ran smooth and free. The piston, despite being considered the "consumable" part of the mechbox, had absolutely NO WEAR on the teeth whatsoever. Once I got it cleaned up, I could have almost passed this off as a brand new piston. The piston head was also in immaculate condition, as were the rest of the internals. The only worn internal was the cutoff lever which wore out at about the 25 000 round mark. Otherwise, the internals are in pristine condition...
So now the gun sports a Deepfire 7mm reinforced mechbox along with a new 7mm Modify modular gear set (torque up) for reinforced mechboxes. I replaced the stock spring guide with a metal one I took out of one of Huang's JG mechboxes. Otherwise, all the other parts from the original JG mechbox made their way into this new shell. With the same JG compression parts that previously gave it 320-330 fps, it now shoots 345-355 with the new setup.
So I think this definitely speaks volumes for the durability of JG guns when you can get a good one...
Last edited by Crunchmeister; April 13th, 2009 at 00:56..