The Pelican Storm Cases iM3300 Long Hard Gun Case has interior dimensions of 50.5" x 14" x 6.0", meaning you could absolutely fit two full size AR15 rifles in this case. The Vault V800 has an extra 2.5" of interior length and 2" of internal height, meaning it will better accommodate two rifles especially if you have LPVO's or scopes mounted to your AR15's. Either or should work fine but I would lean more towards the V800 if you have, or are planning on using an LPVO or scope on your AR15's.