User blog comment:Apepa/More powerful Frag Grenades for the Stimulus Package!/@comment-1079585-20100319205033

Weapon classes are assigned mobility values. They do not have actual weight. Picking up a weapon does not change your mobility.

SMGs and Snipers (including the 30 pound Barrett) - 100%

ARs - 95%

LMGs - 87.5%

Riot Shield - 80%

You always have the mobility of whatever primary you spawned with (or swapped to with OMA until your next swap).