KWA MP7 Question
 

Hey,

I tried searching but came up with a bunch of conflicting information on numerous forums. I will be getting the KWA MP7 and am worried about the hop-up swelling.

First of all, is this still an issue on the currently produced MP7s? If so, what do the current users of this gun use for gas? A certain green gas brand? Propane with a certain adapter and only adding specific amounts of silicone oil?

I have a WE SCAR and I find that my madbull propane adapter keeps it running pretty wet with oil. More so for the first 5 or 6 mag fills then it tends to dry up if I don't refill. By using this adapter will my hop up swell? Some people say they run dry propane and just oil the parts in the gun. My experience with the WE system is that if you don't have silicone in the propane it will dry out the nozzle O ring very fast.

Any advice from people who own or have owned the MP7 would be greatly appreciated!

Cheers,

Keith

I've always put a few drops of silly oil in my propane, never caused any issue for my KWA MP7...I had pre-ordered mine and I'm not sure if there were any design revisions since. But I've heard about the swelling hopup though I've never had that issue as after each game I tend to clean out my whole gun.

I dont add oil to my gas as often as it is suggested for. Usually once every 25 fill or so.

I did encounter hopup swelling, three times on three different guns, it's not matter of propane+oil vs green gas it's both. If there's excessive oil (both are usually used in excess, it will swell after 5k)

hopup rubber is rather inexpensive and readily available for kwa guns, if you're that concerned about it, order an extra and have it on hand to put in if you need immediate replacement.

dont lube your hop up period!

KWA Mp7 is pretty hard to access the hopup bucking, it'll take me ~20 to disassembly it (and about 30 minutes to reassemble it. First time took me over an hour to reassemble)

Thanks for the information, Do you use a light oil? I have been purchasing the "AI Lightweight Pure Silicone Oil 1.5wt" from Airsotparts.ca and using that in my madbull adapter. I think I may get another adapter and just put a few drops in every 20 - 25 fills like you mention to avoid the hop up swelling.

As far as installing a new hop up in the gun, would you recommend an aftermarket one? I have read that there is a Falcon hop up that does not swell. If/when I do need to get the gun apart do I need any special allen keys? I believe I read somewhere that the gun requires a uniquely sized allen key to get to the hop up.

Thanks

As Kullwarrior was alluding to, the KSC/KWA is a pain in the ass to get to the hopup rubber. You'll want to completely minimize the number to times you ever break the gun down that far.

And you don't really need to if you use your common sense a bit. Stick with 1-3 drops of lightweight (1.5wt) silicone oil in your propane adaptor (refering to the AI design). If you're using the MB resevoir one...then don't put so much oil into it...or don't put any in and just add 1-3 drops to the top of the tank before you put the adaptor on.

Oil is good for the piston cup, the internal touching/bearing/friction surfaces, and the seals in your mags.

While it will blow most of the oil into the first mag and much less into the other mags...if you rotate your mags eventually you'll end up with oil in them all at some point. You do not need oil in every mag every time.

If you can't sleep without knowing that there's some oil in each mag...then leave your tank/adaptor dry and just put 1 drop on the fill valve of each mag before you fill it.

Don't overdo the oil on the KWA/KSC MP7...it's much more like a GBB pistol than it is a closed bolt WE SCAR. A drop or three now and then is enough.

interesting to learn that about the mp7... I've been considering buying an mp7 or an mp9 I'll need to look into ease of service when it comes closer to buying.

KWA used to put a little drawing into the manual showing the user pouring oil into the rubber. But yes too much oil means that it swells.

It is kind of a pain to get to, But I still think I prefer it to an AEG.

Maintenance is fairly easy. The parts that need to be lubricated regularly (bolt) is easy to access. As long as you don't oil it too much and have your hopup rubber swell, you're golden when it comes to maintenance. Otherwise, the MP7 design is pretty bulletproof. Haven't heard of anyone having any issues with the gun other than the hopup swelling.

Yeah, I'm generally not terribly afraid of maintenance, even if I replace the hopup rubber once a year an hour of work is not a huge concern. What concerns me is the robustness of airsoft parts in general and their durability in terms of repeated assembly/disassembly.

The swelling is also caused by idots using the wrong type of Silicone oil (IE the Canadian tire stuff, not 100% stuff), and then putting the oil directly on the hopup (don't do that). treat it more like a pistol as m102404 pointed out and you will be golden.

First time you take it apart its not so bad, but I had a hell of an issue putting the trigger back in.

Thanks again for the information,

one final question, what type of oil should I use for the bolt? On my WE Scar I have been using grease on the metal bolt as the silicone oil wasn't really allowing it to slide well. For the MP7 bolt should I just stick with the silicone oil provided by KWA? Does anyone know what weight it is so I can purchase more from a hobby shop in the future?

yeah I make sure the oils I use on my guns are all silicone or rubber safe... anything out of an aerosol can is bad since it uses petroleum distillates as propellant.

Ok i jsut had this issue with my KWA MP7

Lube your mags a little less then you would with your normal GBB mags

DO NOT lube your internals with silicone oil, use either grease or graphite filings. Both will work fine but remember to be light on the lube, use just enough. Remember to keep all the lube away from the air nozzel and the hopup. As soon as silicone anything touches the rubber it expands and there is no going back.

IF YOUR RUBBER SWELLS do not panic! You can order them directly from KWA for a couple dollars a peice. I recomend having them on hand if they do swell.

There are a couple videos on the internet which show you how to replace the rubber because this is such a frequent problem. This video should be useful. It is very easy to do this, just remember to be gentle with the gun and when you take out the mechanism from the reciever to tape the selector parts down so they dont fly out. The hardest part of the process is getting the trigger back in, make sure your spring looks like the one in this picture and is not bent all screwy.
http://i181.photobucket.com/albums/x...0309-00133.jpg


kwa mp7 replace hop up disassemble and reassemble p1 - YouTube

If you ever need help with the assembly please shoot me a PM, I will be glad to try and walk you through the process.