go ahead and start using the flare gun and rifle gun as weapons by now. There is no reason to save them since they have little use for the last part of this game. The only weapons that help out a bunch in the final area are the revolver and the submachine...
but the Revolver and Rifle can work as well. Make sure you have plenty of ammunition if you are bringing the gun along since this will be a long battle. Around 40-50 rounds would be recommended.