Stuey Posted November 18, 2012 Report Share Posted November 18, 2012 Hi all, I'm hoping some genius can help me with a particularly vexing issue with my KWA MP7. Usually this thing runs like a train but today it wasn't having any of it - it fires BBs only some of the time, and it sounds weaker than usual. It's not cycling fully either because the bolt doesn't go back far enough to lock when the magazine runs out of BBs. Most of the time it doesn't even have the power to push the BBs past the hop-up rubber, so with each shot it just fills up the barrel with BBs. I'm stumped, I can't see anything obviously wrong with it, what could it be? Problem with the floating valve? The hammer spring (would explain the low power)? The mags even? Halp! My favourite gun is borked. Link to post Share on other sites
DrAlexanderTobacco Posted November 18, 2012 Report Share Posted November 18, 2012 When was the last time you used it? Link to post Share on other sites
Stuey Posted November 18, 2012 Author Report Share Posted November 18, 2012 Errr, before today? Last Saturday. And it gets lovingly maintained after each skirmish, that's why I'm so confused Link to post Share on other sites
Danke Posted November 18, 2012 Report Share Posted November 18, 2012 Your hopup rubber is swelled. That's all that is wrong. Swap it out and i'll run like a train again. Link to post Share on other sites
bbstriker Posted November 18, 2012 Report Share Posted November 18, 2012 I would 2nd that. Swollen hop rubber is common with stock hop- up rubber. I had same issue and then carefully disassembled the weapon, replaced hop rubber and it now fires like a dream- again! Avoid lubing the breach chamber when you've replace the hop rubber - if that's what you decide to do. There's a YouTube vid on this. Link to post Share on other sites
msx361 Posted November 18, 2012 Report Share Posted November 18, 2012 There is also talk of soaking the hop rubber in warm soapy water. Make of it what you will. Replacement kwa hop's can be got from kwa pro store in the US, good luck finding one in the uk. Or there is the falcon hop rubber, which is getting harder to find, again good luck finding one in the uk. If you can wait a few a days (maybe a week) i just ordered a kwa hop, but then found a falcon one in stock and my original started working again, so you can have the one i just ordered for cost of postage (£2) if you want it? PM me Link to post Share on other sites
Stuey Posted November 19, 2012 Author Report Share Posted November 19, 2012 Ahh dammit I can't believe I forgot about the hop rubber swelling up I - know it's an issue with this gun, completely slipped my mind. I don't have a spare rubber but I'll take it out and wash it tonight. I did try the Falcon rubber for a while (which apparently doesn't swell up) but it essentially ruined the gun, giving me massive over hop even on minimum and removing all semblance of accuracy/consistency. The MP7 shoots fantastically with the stock rubber so I'm just going to stick with it. Link to post Share on other sites
Danke Posted November 19, 2012 Report Share Posted November 19, 2012 Buy a few at once. I dont' like washing it out since you can't be sure when you put it back if it's good enough to work again. If it's your only choice though then it's your only choice. It's the same as the KSC Glock so if you can find one of those. Link to post Share on other sites
Stuey Posted November 19, 2012 Author Report Share Posted November 19, 2012 Well I washed it and the gun seems to be back to its normal awesome level of performance, plus I've hopefully acquired a spare from msx361. Otherwise WGC usually have them and fairly cheap shipping. Thanks for the help chaps! Link to post Share on other sites
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