Would this be overpowered?

GarethQ

Well ive been picking my nose and reading M203 listings on eHobby Asia and was wondering, if I pick an M203 would it be above 1 joule before its imported, and if so is it best to ask for a downgrade on power?
http://shop.ehobbyasia.com/other-gun/grenade-launchers/king-arms-m203-qd-grenade-launcher-short-1.html
Thats the M203

evilrobotshane

It won't be above the Joule because it doesn't really do anything; it's the 'grenades' that you put in them that hold and fire the BBs (and they can do it without being put in the launcher, too). So the grenade launcher is fine, it's the grenades you need to worry about, but I don't think they have the oomph to get anywhere near the Joule anyway.

GarethQ

So an idea would be to import the M203 and get grenades from the likes of MIA

Spooky-Vinny

I honestly doubt you'd hav any trouble with the fps of a nade...
xXx

Firekitten

output of green gas grenades in Irish conditions is roughly 200-250fps. Enough to wallop out a load of bbs, but not significantly 'omg'ish. Should be grand. Though I'd avoid C02 grenades,

NakedDex

Without a grad-card and a high speed camera, it's not really possible to "chrono" a 40mm grenade accurately. I've heard - anecdotally - that an average 120rnd grenade on green gas fires it's rounds at about 200fps (+/- 30fps for manufacturer) at our average temperatures and pressures, and CO2 at around 270fps (+/-20fps).

It's something I've been curious about, but it's difficult to test without said equipment, and grenades themselves are temperamental at the best of times. They also vary wildly from manufacturer to manufacturer, and even vary with the firing mechanism chosen.

Bemused

Just curious about a couple of the responses:

Dex, why would the output depend on the "firing mechanism"? Something to do with the difficulty of firing at higher pressures?

Firekitten, why would you avoid CO2 grenades? I'm just getting some M203s for the first time and am more inclined to go with CO2 for better range. Are you shy of them because of reliability issues?

Thanks for any replies.

NakedDex

The faster you can push the firing pin open, the better. It's essentially a slam-open gas valve, so a rapid, controlled operation is required for reliable readings if you're measuring output.
For example, comparing a Madbull XM203 and a regular M203, the Madbull has a direct-push trigger rod which requires a lot more force to open the valve than the levered, indirect-pull trigger mech of a regular M203.
Similarly, an Star/Ares AG36 will have a different trigger weight to a Star/Ares EGLM due to configuration differences, despite both being levered, indirect-pull triggers made by the same company.

Also, I'd be fairly sure FK was referring to the CO2 grenades being possibly over the 1J limit, but the whole grenade power issue is a gigantic grey area of unclarified definitions and difficult testing procedures.
I've personally heard nothing of them being possibly over the limit without modification. it is possible to bore out some higher quality grenades for increased gas capacity, or even make extensions to them for same. Not recommended at all (though few will try given the required machinery and expertise), but certainly possible.