Question: are shotguns good in siege?
Answer: To be honest, all the fast-firing semi-auto shotguns are pretty good. This includes the FO-12 (Ela), SASG-12 (Kapkan, our lord Tachanka, Finka), and the SPAS-15 (Caviera). You'll need to adjust your play style a little since you traded the versatility of SMGs for close range power of the shotguns.