Should an AR-15 carbine be kept in condition one for the purposes of self preservation within the domicile? Or, is such a practice dangerous and is the AR system not designed for keeping a round chambered with safety on for an extended period?
This is a good question, and one we've discussed several times (one example
https://www.thehighroad.org/index.php?threads/ar15-bolt-closing-issue.728414/ ). There may be mitigating factors general to all firearms as others have mentioned around children or others in the house, but SPECIFIC to the AR15...
I strongly recommend you store with loaded magazine, and bolt CLOSED on an EMPTY chamber, and I prefer safety on, because i train to flip the safety off as my sights come on target and to put the safety back on when i drop to low ready. There are 3 things about the AR that combine to result in this advice.
First, Please perform the following experiment yourself to familiarize yourself with the action:
1. ensure rifle is unloaded by removing the magazine, cycling the CH and visually and digitally inspecting the chamber
2. lock the bolt to the rear and push the CH forward.
3. hold the rifle muzzle up, maybe 6" off the floor, and then drop it so that the butt hits the floor. (it's ok to keep your hand on it so it doesn't fall over and scratch something up)
What you should find is that it takes a minimal amount of force to close the bolt. The bolt is held back by a spring loaded lever. If you take the weight of the bolt off it for an instant (by bouncing the butt on the ground), it will retract, allowing the bolt to go forward into battery.
This is important because a lot of unexpected things could cause your rifle to fall over and load itself. If you lean the rifle up against a wall, and something brushes it and knocks it over, the bolt could close and now the gun is loaded. If your gun is in a car bolt open, and you come to a very sudden stop, it could also close the bolt.
Second, slamfires are a possibility. Although quite rare, they can happen, so always keep the muzzle pointing in an especially safe direction when you send the bolt home. Next time you're at the range, put the AR selector on 'safe' and load a round in the chamber, then eject it without firing. When you inspect the round, you'll see a dent in the primer from the firing pin. Why? The AR has a floating firing pin. There's no spring holding it back. It always bounces off the round when the bolt slams forward, but lacks the mass to detonate an in-spec primer. Of course, a combination of a sensitive primer, slightly out of spec pin or bolt, or whatever, maybe combined with excessive dirt, etc. could cause a slamfire. Member 'slamfire' here at THR has documented many of these.
As a result, if you are the kind of person who loads a rifle once and lets it sit there for a decade or two, the risk of a slamfire may be low enough to ignore, but if you're the type who shoots your defensive weapon a few times a week all year, plus cleaning and other misc handling, resulting in loading and unloading it daily, my opinion is the risk adds up, so I just don't chamber a round in my house, and recommend others don't either. And ESPECIALLY, don't chamber your precious $3/round super killer defensive round over and over, double especially if it's not crimped in a cannelure. bullet set-back is a thing. and also, while I have no evidence, I'm concerned continually smacking the same primer with your firing pin could either make it more sensitive, or not go off when you need it. If you are going to chamber a round, rotate it. You should have 30 in the mag. Just put a different one in the chamber each time. When you eject a round without firing it usually the ejector pushes the bullet into the lug in the barrel extension, causing a long scratch down one side of the bullet. It's a fairly reliable way of telling if you chambered a round before.
Third, the AR "safety" selector is not a firing pin block. It just prevents the trigger from being pulled far enough to the rear to release the sear.
so, worse case, you lean the rifle against the wall, bolt open, loaded mag, and your dog runs by and knocks it over, causing the bolt to close and slamfire, sending a bullet into something you really didn't want shot.
leaving the bolt closed on an empty round makes that practically impossible. and it saves you from the temptation of rechambering the same round several times.
bolt closed also prevents dust, cat hair, etc from collecting in the action as it floats by and sticks to whatever lubricant you use
now, all that said, there's nothing about the hammer or trigger springs that would cause an issue being left cocked for an extended period of time. in fact, my recommended bolt closed on empty chamber, safety on means the hammer is cocked and spring compressed. if you wanted, you could do the IPSC "slide down hammer down" thing, and close the bolt on an empty chamber and then dry fire it to take pressure off that hammer spring, but i can't think of a good reason to do that aside from preference or some other training or habit.
