I find it hardly likely that it would be lower given you would have to factor in accidental death, suicide, murders within gun owning families, etc, and on the other side there are just the situations where owning a gun actually stopped you being shot, which are obviously much much less and often end up with the other gun owner shot, so effectively reducing that number still further. It seems fairly obvious that proximity to a deadly item increases the chance of being killed by it.

Surely those who frequently encounter dangerous situations or routinely feel that their safety is at risk are much more likely to own or carry a gun (e.g. retail business owners). I'd wager that this self-selection bias skews the statistic significantly.