The MP5SD6 in my opinion is an assault rifle, I'm saying that because I know a lot of people say its a back up weapon, with a silencer, its barrel it greatly lengthened and I just love everything about this gun. You can get this gun at many places like HitGuns(i got mine here), AirsoftGI, Evike, and ShortyUSA.
Being my first airsoft gun, I thought it was the best, I now know I was slightly wrong, after all, it was only $100, but for the money, its awsome. Picking it up, it was quite heavy, at about 4.6 pounds it felt powerful. Being winter when I got this, I could easily identify the many metal parts on this gun. The foregrip has a nice tough rubber-ish material covering it, which doesn't slip. Since I love Heckler & Koch, I think my review will be very positive.
Being an H&K gun, I loved the look of this gun, it has a nice slick black/gray tone color to it. The rotating back sight gives you 4 different view for all types of ranges. And the rubber reinforced sliding stock feels very comfortable. Looking at this gun, you can already tell its great, most of it looks metal, but closer inspection shows that the silencer, the foregrip, the grip and area around the fire selector are all plastic. The Stock, Upper Body, magazine, front sight, back sight, fire selector, and many other parts are metal.
This gun feels great, very heavy, though light enough for me to hold it out like a pistol. (which probably isn't good for my wrist joints xD) The sling I ordered from Hitguns is hard to fit on, so I improvised. Wearing this on your back is comfortable, as long as the charging handle isn't jabbing your back.
This gun works great, with .2's and a well adjusted hop-up this is accurate for who knows when, it went so far and straight I lost sight of it. The rate of fire is very quick, 700+ rounds a minute on a well charged 8.4v battery. This thing hurts too, being my first airsoft gun, I decided somehow I needed to feel what 350 FPS was, it hurts, a lot! I've probably fired just under 1000 rounds in many varying weathers, rain, snow, sunny, humid, this gun has stepped up to the test.
Being an MP5SD, it comes with a silencer, which, to my ears does actually silencer it maybe a few decibels.
Sadly, it's not easily modifiable, it's possible, but hard. With a $50+ RIS foregrip and a $30 mount for a red dot sight, I wouldn't think its worth it. I ordered a mount for a scope for it, its nice, but I'm not going to talk about it much since I have a part review here.
Overall, this is a great AEG, and a great starter gun. It can withstand rain, snow and heat, and can keep up the fire for a few hours on the battery it comes with. Id give this a 9/10, only because the hop-up isnt very responsive, but for $100, this gun is great!
This is a great gun, definitely get it if your looking for a gun to get. Good Gun JG!