|Leave this at home when the crap hits the fan? Crazy?|
In full apocalyptic battle gear, with a rifle in hand and a load of mags to back it up, carrying a sidearm is still considered pretty standard wisdom. If your primary goes down, at least you've got a pistol to turn to, right?
Of course, at standard rifle engagement ranges, a pistol isn't worth a whole lot. Better than throwing rocks, yes, but a guy with a pistol versus a guy with a rifle is not an especially fair fight...put 50 to 200 yards between 'em and it just keeps getting worse. At that point, you better hope you brought friends.
You did bring friends, right?
Let's face it--rifles don't have catastrophic, 'out of the fight' failures very often. If your primary goes down due to a common stoppage, then it can be resolved and put back into the fight quickly. Being able to instinctively ID a malfunction and resolve it is critically important and something you should train for anyways.
So, 99% of the time, if your primary goes down it's due to running outta ammo or some variety of simple malfunction.
Transitioning to a sidearm is faster than reloading or clearing a malfunction--no argument there. But fighting and especially reloading should be done from cover, not standing out in the open with bullets flying around you. You should also have those well-armed friends you brought along with you, to pick up the cadence of fire when you need a few seconds to get your weapon back up and running. Fighting from cover, with teammates fighting with you, you've got that extra second to reload your rifle and get back into the fight in a meaningful way.
What if you run out of ammo for your primary? If the gunfight is that bad--if you're only left with a pistol to fight with, you should really be withdrawing or relying on your buddies to finish the fight. If you can't withdraw...well, I 'spose at that point you'd want a handgun for making your 'last stand' against enemy forces.
Talk to vets from the wars in Iraq and Afghanistan; read the accounts from the Special Operations Forces guys. They rarely, if ever, use sidearms in combat.
And we're not soldiers. As a civilian in a post-collapse scenario, if you've got a rifle in hand, a load of magazines on your person and a couple of similarly equipped buddies in town, your odds of needing that handgun are really, really low.
Given the relatively low utility of a sidearm in a gunfight, would you be better off using that weight and gear real-estate to carry something else? How about more rifle mags? A loaded PMAG weighs in at just over a pound, so you could carry 3-ish extra rifle mags for the weight of a pistol + 3 mags. 90 (more) rounds of 5.56mm sounds a lot better to me than half as many pistol rounds. Not that the 3-ish pounds of total weight should be the deciding factor behind carrying one - just an example.
For further reading, Max Velocity - who carries a pistol on his battle gear - has a good post up on what he thinks is an over reliance on pistols in today's tactical training. Good perspective from someone much more knowledgeable than I.
Edited to clarify: This is discussing a scenario that would require you to don whatever full level of combat gear you have - chest rig, plate carrier, battle belt - and have your rifle within arms reach constantly. So you're on active patrol/guard duty after a major collapse, for example. Not a scenario where the rule of law is still largely in effect and concealment is important, or you're rambling around your homestead doing chores and may need to set your rifle down.
What do you think? Anyone purposefully run without a pistol? Would you?