Keith and Bill,
Sorry, can't help you with this question concerning the inside pocket. Reading through the posts, do I read it right that you really don't know what haversack is in question? You need to be certain which haversack. Having an inside pocket in a bag used for carring artillery rounds is possible but unlikely. To put any object in that pocket while carrying a live round is not good policy. In fact, knowing could would happen depending on what was put in the pocket makes me think this is not a gunner's bag for carrying live ammo, maybe for personal use. These thoughts are just reflections as I do not know about this inside pocket in a haversack.
Ron