If you are going to "always have the pistol with [you]", then I would only carry a shotgun. 12 or 20; your choice. I'm not sure how much you gain by having a second pistol caliber or second barrel of your carry pistol with you. Also,none of us can be sure of an "always" condition.

2 cents
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"Its not a matter of being ready as it is being prepared" -- B. E. J. Taylor