AR 15 dumb??

[DDriller]

My vote would be the 458 Socom if you haven't bought yet. Get it from Tromix and it will run well. He built the first one and has the proper bolt and extractor needed for the round. They are a blast to shoot.

[yeahbub]

I read about a chambering conflict between .223/5.56 and .300 BO which has led to disastrous results for some who own both. It seems that .300 BO can be chambered in a .223 rifle without noticing and the results are the sure destruction of at least the rifle. It's disastrous to send a .30 cal bullet down a .224 barrel. The after-action and sectoned barrel photos show the bullet in the barrel beyond the end of the chamber but now well over an inch long and jammed in place. After having read of several such episodes by experienced shooters, it was an easy choice to not get the .300 BO. The 7.62x39mm uppers will go on the same lower and easily yields low-end .30-30 performance without difficulty. There's no possibility of getting a 7.62x39mm round in a .223 chamber. Here are some links:

https://www.nrablog.com/articles/201...k-ar15-kaboom/
https://www.thefirearmblog.com/blog/...-5-56-chamber/
https://www.windhamweaponry.com/bewa...ophic-results/



If I had no .223/5.56 rifle, sure, a .300 BO would be interesting to explore, but after many incidental lessons in life about just how fallible I can be on occasion (fortunately without permanent disability), there's no way I'm setting myself up for a Murphy-takes-all losing hand. I like my parts and my rifle too much to not pay attention to what looks like something that's begging to happen. Other folks seem to own both and get along without this mishap, but this looks too much like the back route into Mordor to me.

[Texas by God]

If the 7.62x39 would function well in the AR, the .300 BO, .30 WT, and .30 Hamr might not exist. But it doesn't and they do!

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[yeahbub]

Greetings, Texas. It's my understanding that the .300 BO was originally developed to be a low-volume case for primarily subsonic use, the low-volume feature assisting in keeping pressures and velocities consistent - and it does. Another plus is that the same bolt and carrier are used with either the 5.56 or the BO. Less to buy, at least in theory. I've noticed, and others have mentioned that once I have another upper, moving my bolt and carrier from one upper to another is an annoyance - better to have a BCG for each of them. The .300 BO was not designed because the 7.62x39 couldn't be made to function in the AR's. As for your claim the 7.62x39 does not function in the AR platform, well, I'll have to disagree. True, the AR's were designed around a case with less body taper, but 7.62x39-specific magazines are available and they work. Teething trouble with this application? Maybe, but doesn't .300 BO, .30 WT, and .30 Hamr occasionally suffer from the same thing? My comments are about avoiding a serious accident, which still stands. The .300 Bo is an interesting and useful round, but I dont' need it bad enough to risk an accident as photographed on the links I posted previously.

[Texas by God]

I only have hands-on experience with one AR chambered for 7.62 Soviet. Perhaps my friend did not have the magazines you mention because it was a jam o matic. I do notice that Rock River Arms build a special lower for their version to get it to work with AK magazines.

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[popper]

I keep hearing of the BO 223 problem. Are we so complacent in loading our guns we can get mixed up?

[yeahbub]

Another really interesting possibility is the 6.5 Grendel, capable of remaining supersonic at a thousand meters. Sounds like just the ticket for long range competition.

Texas: I have seen that Rock River lower built for Kalashnikov mags and it's an interesting piece of work. At first glance I had to wonder if I was imagining things. It looks like it would work and I wonder if it's an answer to the problems others have had with a conventional lower. The case taper on the Soviet round is pronounced and doesn't lend itself well to straighter mags. I had heard comments from folks using 5.56 AR mags saying anything more than 8 rounds or so was asking for a mis-feed. The AR mags intended for the Russian round are distinctly curved below the mag well a good bit more than the usual 30-rounder and are readily recognizable. I was hot to get one of the Colt produced AR's in 7.62x39 some years ago, but the "assault weapons ban" prices were in low earth orbit by the time I got the bug. I'd still like to try, as it would be nice to have a truly accurate AR in that caliber, but there's also other spiffy deer-legal AR chamberings, like the afore-mentioned 6.5 Grendel, also based on the 7.63x39 case but straighter and operating at somewhat increased pressure. The temptation is to use the 7.63x39 BCG, and people do it, but this is considered a no-go by those who push the Grendel to its limits. The problem has to do with the increased diameter of the counter-bore into the bolt face reducing the strength of the lugs. There is, though, a re-designed bolt specifically for use with the Grendel, so this problem has been overcome. From what I read, it's best to use mags built for it, as it also seems to have had some teething trouble in the beginning.

Popper: I saw a blowup happen during a high-power match a few years back. The .300 BO wasn't involved as it wasn't invented yet. It was an overcharged case from the look of it, massive extrusion and failure into the magazine and from what the competitor was able to tell us. It sure split that upper clean back to the ejection port. No one was injured, though. The shooter was a longtime competitor, rarely used ammo he hadn't assembled himself and was a veteran at it. It happens to the best of us.

[dragon813gt]

I keep hearing of the BO 223 problem. Are we so complacent in loading our guns we can get mixed up?

Yes, people are that complacent. They aren’t paying enough attention for that to happen. I don’t own a 300 BLK upper. But I do own a bolt gun chambered for it. There’s no reason that ammo for the bolt gun should ever end up in an AR magazine. But I can only control myself. When my kids are of age I can guide them. But if they decide to do something stupid when I’m not around I can’t prevent it. Never underestimate the intelligence of stupidity

[am44mag]

Yes, people are that complacent. They aren’t paying enough attention for that to happen. I don’t own a 300 BLK upper. But I do own a bolt gun chambered for it. There’s no reason that ammo for the bolt gun should ever end up in an AR magazine. But I can only control myself. When my kids are of age I can guide them. But if they decide to do something stupid when I’m not around I can’t prevent it. Never underestimate the intelligence of stupidity

That's my biggest concern. Complacency can happen to anyone, but I'm more worried about someone else making that mistake despite my best efforts to teach them. You can't be everywhere at once.

[DDriller]

If you want to have some fun get a .458 Socom from Tromix. Basically a semi auto 45-70 with a lot less recoil. Your current mags will work but the 30 round will only hold 10 of the 458 cases.

[pakmc]

if you have several AR's that all look alike, I really liked the hand guard of a certain brand, you can get them mixed up easly. I did and I did put a 300blk in a 6mm barrel. and yes, I survived the experience. but the upper didn't! I was able to save the lower. but the 300blk is very cheap to shoot, brass is cheap and if you use puller .308 mil. bullets they are cheap also.(147 or 150gr bullets), but so it .30 caliber carbine(cheap to shoot)

[Winger Ed.]

The family bought me a Anderson multi cal. carbine in 5.56/223 and I was wondering can I buy a 300BO upper and put the lower on it ?

The .300 is fine, Now you need to get some pictures pictures of a .50BMG upper
and stash them around like the kid did for his Red Rider BB gun on 'Christmas Story'.

[Texas by God]

I still have a scaled down version of the single shot BMG upper in 7mm Mag bouncing around in my head. That would be a cool option to have on top of an AR 15 lower.

[dragon813gt]

50 BMG on an AR lower? No way I would ever shoot that. Not nearly enough weight to “tame” the recoil. The $2k+ price tag is another reason to never buy one. That’s one cartridge I’ve never had any interest in.

[Texas by God]

50 BMG on an AR lower? No way I would ever shoot that. Not nearly enough weight to “tame” the recoil. The $2k+ price tag is another reason to never buy one. That’s one cartridge I’ve never had any interest in.

Me neither. But I would shoot a 7mag version. I'd slip a limb saver on first

[Winger Ed.]

50 BMG on an AR lower? No way I would ever shoot that. Not nearly enough weight to “tame” the recoil. The $2k+ price tag is another reason to never buy one. That’s one cartridge I’ve never had any interest in.

The cost is about even with buying 2 high quality center fire rifles, which is reachable.

The deal with recoil is solved by the brake. Without one, it can brake your collar bone.

[dragon813gt]

To each their own. I live in an area where the woods are thick. A 35 Remington gives me more than enough range. I’ve shot a Barrett and it does nothing for me. I’m all for people getting whatever they want. But I’ve never had an interest in that cartridge or most big bores for that matter.