the 10mm uses a straight style mag, which obvoiusley this is modeled after, cause it's also the only model of mp-5 which uses an external suppressor/silencer. As opposed to the mp5sd.
Are the grenades just supposed to be slugs, they don't explode, and there shaped like HE grenades not 40mm slugs. Also, why not do a masterkey shotgun attachment.
On a real smoke grenade
1-the lever/handle comes OFF when the ring is pulled
2-the smoke comes out the TOP
3-There is a 5 second delay before the smoke starts pouring out.