Not every day I get to correct Mojo.
Kevlar shoot packs have about 20 to 30 layers of woven Kevlar fabric. The are only useful in stopping rounds from a handgun.
Bullets fired from a rifle (typically) will pierce thru a Kevlar shoot pack. The military uses hard inserts to stop rifle rounds. These inserts are called plates. Not sure what they are made from. Some are ceramic, I believe. A newer plate is made from a dense plastic that stops bullets in part by slowing their rotation.
Kevlar: handguns; hard plates, rifle rounds.
Like you, I think it doubtful that DS or ‘pure spider silk’ will be useful in shoot packs and they sure won’t work as a replacement for hard plates. Groin protection may be the best military apparel application, but only if that pesky super contraction problem is fixed.