In the OR we have topical coagulants (applied directly to the wound) used to control oozing. For that use they work well. They are not typically used for cuts in large vessels during surgery. To the best of my knowledge, the products we use are not intended for field use.
However, if the Army has coagulants for field use, they are very likely of benefit in some situations. My ignorance on this topic keeps me from telling you exactly what those situations are. Directions on the package and website information might be helpful.
Direct pressure is the best way to control bleeding from a large vessel/spurting artery. If you press a bandage on the wound, the thicker the bandage, the more dispersed and less effective the direct pressure is. In the OR we use a tourniquet above the wound for direct pressure. In the field, your finger or hand can be effective for applying pressure.
Whatever you do, seek help/medical attention right away!
If you decide a coagulant is worthwhile to have, be aware that most medications have an expiration date...usually no more than a couple years down the road. Replace with a new product at or before expiration time.
OkieG