Discussion in 'Rifle Country' started by EMT40SW, Sep 29, 2022.
I color code the magazines with tape on the magazine and on the dust covers
5.56, Black (regular magazines)
300 BO, FDE (Magpul)
350 legend, Green
450 Bushmaster, Blue
I use orange tape and sharpie on my 300blk mags so anyone, not even me, can tell that they aren't normal.
I also keep all my ammo in labeled ammo cans so I don't mix anything up. Never loose rounds.
I almost never bring both a 300blk and 5.56 to the range at the same time and I empty my range bag after ever trip.
So, a person could build a blue AR for a given caliber, and a red one for yet another.
AR, in large or small frame offer so many possibilities as to make this as easy or as difficult as a person could desire.
In practice, not 100% sure, but I wouldn't lose sleep about it.
As for .300, presumably the bullet width wouldn't allow the case to headspace into the chamber, so the BCG would be out of battery where the bolt stops, and in any lower that's close to in-spec, the hammer will hit the BCG shroud before the firing pin. If your bullet is seated deep enough that it won't hit the chamber shoulder before the bolt is in battery, I suppose that could be an issue....but I can't say for sure, as I haven't played with loading .300BLK.
I mean, if it's a major concern, just make sure you only have one out of it's case at a time, keep the ammo separate and clear any loaded mags before switching rifles.
For 5.56 I run translucent Lancers, so I can always take a quick glance if I'm not 100% sure.
I also don't bring 5.56 and .300bo ARs out at the same time, one or the other, and each caliber stores in a different ammo can.
The force of the bolt running into the case is enough to push the bullet back into the case until the bolt closes. At that point the cartridge head spaced off the bullet and will fire.
I learned this when a neophyte buddy loaded and fired his .45 Colt revolver after grabbing .44 Magnum loads out of the wrong ammo can. If it wasn’t an old model Vaquero that he was shooting, it could have been catastrophic.
Unless you build two exactly identical rifles, it should be easy to identify them.
If you are you worried someone about mixing up your rifles and blowing them up you should limit access to non-idiots.
Byron had a habit of buying multiple identical handguns. Sometimes they would be identical in every respect, and sometimes they would be the same except for caliber. He became somewhat more cautious after slapping in a mag of 10 mm in his Dan Wesson 1911 .45, and touching off a round. Fortunately, there was no damage or injury.
Unless you end up with both inch and metric mags somehow!
Or worse, you end up like my buddies Century FN FAL. It wouldn't run with either inch or metric. Just the one mag it came with. 5-6 of both types wouldn't run more than 1-2 causes cartridges at a time if at all. That one mag it came with ran pretty well though. But it somehow didn't match up with either inch or metric. Just Century being Century I guess.
So given that paradigm, we could never rely upon any procedure - such as marking magazines, ammo, or uppers, or separating/segregating ammo, or only loaning out one rifle and matching ammo at a time, etc. Any procedure like this is not infallible.
For example - despite marking magazines, an unwitting shooter might not realize the meaning of the markings (different sized mags or colors), or the markings may fail (bands slipping off or breaking), or a person still might load the wrong ammo into the magazines, or simply grab the wrong rifle, or assemble a non-5.56 upper onto a 5.56 marked lower, or a person might put ammo into the wrong box, or put a box of factory ammo on the wrong stack or shelf, or… or… or…
Physical/mechanical safeguards DO constitute full value ISL’s, so mechanical safeguards are far more reliable than procedural - human dependent - safeguards. We like to pretend in firearms world that our procedural 3 rules of gun safety are the highest safeguards, but statistically and factually, mechanical safeguards always promote greater safety than procedures. Bluntly, you are more apt to forget to activate a mechanical safety on a rifle, or inadvertently deactivate the safety than the mechanical safety is apt to fail - AND - good PSM programs require methods to regularly confirm function of safeguards.
But physical fit is a mechanism which cannot fail - so quite literally, owning the 300blk is the only real risk in this scenario. There is no other combination of cartridges between which the larger bullet diameter cartridge will fit into the chamber of a smaller bore cartridge. 6.8 SPC, 6.5 Grendel, 204 Ruger, 17 Rem, 20 Pract, 6 ARC, 223/5.56, 458socom, 450 bushy, 350 Legend, 224 Valkyrie, 22 Nosler, 25-45 sharps, 7.62x39… all of these have sufficient interference in cartridge dimensions such none of the larger bore cartridge ammunition will fit into a smaller bore cartridge chamber. For the few which CAN chamber into eachother such as 17 Rem being fired in a 223/5.56 rifle or 6 ARC in a 6.5 Grendel rifle, the under-sized bullet will rattle down the bore, with no greater severity of consequence. The 300blk is the only larger bore cartridge which is sufficiently short to successfully chamber into a smaller bore, 223/5.56 chamber, causing a bore obstruction and potential catastrophic failure in a single shot.
So mechanically, no combination of cartridges and rifle can present a significant risk if you do not own a 300 blackout. If you DO own a Blackout, then there’s really nothing beyond fallible procedures which can prevent a Kaboom, which then requires at least two procedural confirmations to promote a single layer of safeguarding.
This whole thing is partly why I'm on the fence for a 300blk.
I can go 7.62x39 or 350L with almost as much ease and similar performance, and a much higher degree of safety. If it was just me, I would be very comfortable with a 300blk, but between the wife and kids, there's a fair chance for a mix up.
It just comes down the "headspace and timing" of the operator, keep your gear basic and simple to what works for ya.
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