Does the Airsoft M4 3181 AEG shotgun shoot single shot or spread?

This gun? http://www.amazon.com/Electric-Airsoft-Grenade-Lau...

No, the drum magazine will not work as the drum/box magazines are Tokyo Marui compatible & the replica you are looking at is a very low quality replica- low quality as in not durable, low quality parts & manufacturing, poor performance, & not Tokyo Marui compatible so upgrading & repairing are not an option along w/ a poor selection of magazines.

Are you talking about the 203 for the "shoot single shot or spread?" I'd guess that it is single shot, & I am pretty sure on that.

I suggest you check out other alternatives at reputable websites such as www.airsoftgi.com, www.evike.com, or www.airsoftatlanta.com. Since you seem to have a cheaper budget look into the following brands for each model:

-G36 Series: JG or Echo 1(JG OEM)

-M4A1/M16A#: JG, Echo 1 (JG OEM), G&G Sportline/Plastica.

-MP5: JG, Echo 1 (JG OEM), G&G Sportline/Plastica.

-SCAR Series: DBoys or Echo 1(Dboys OEM)

-AK47/AK74:*Dboys, Cyma, or Echo 1 (Both, depending on the model, OEM).

-M14: Cyma or Echo 1 (CYMA OEM).

-AUG: JG or Echo 1 (JG OEM)

Please note that Echo 1 does not make its own guns and has either JG, Dboys, or other manufacturers make them & slap on their own trades & a 30 day warranty (which is useless in my opinion as 30 days in not much...). They also make include some "better" internals, but it is not know what they do except they seem to like putting in a Madbull blue bucking which only cost $6...

arent the airsoft grenade launchers around $100 a piece

No now stop wasting money and buy a real gu dumbanus sucker