If your Bersa is the aluminum version, that would probably be the better option over your heavier Beretta. If you are running in shorts without belt loops your options are not very good. An ankle holster is terribly annoying while running. If your shorts allow for a belt I would recommend a Galco fletch retention holster. This can be used in either CC or OC and has an over the top strap to provide retention, also as it holds the gun snugly to your body it will be more comfortable and will not bounce around. You can use one designed for the Bersa or one designed for the Walther PPK or the Sig 232 works just as well.