Wildcatting the .400AR

[panatomicx]

If I haven't seen enough cartridges in this world. I mean, c'mon just look in the back of PO Ackley's books with all those wild permutations of brass with ordinary bullets, primer and powder - what were they thinkin'? Did they expect there'd be some miraculous breakthrough from some odd chamber shape reamed into the breech to come up with a magic bullet? Like, is there really a need for yet another AR-15 cartridge?

Ok, so it can stack twenty-five rounds in a magazine. So? Did I mention it's a big bore, can push over 2,700 FT-LBS out a 10mm barrel? From a little AR-15? Yes!

Okay, so there's a new high-power AR-15 cartridge, the 400AR. It's still a wildcat, so you'd have to convert an AR-15 by adding a custom barrel, off-the-shelf bolt and modified magazine, not to mention making the cartridges - necking, sizing, trimming, etc.

But what about it? Is this just a compromise between extremes? Or is there a sweet spot in the middle? The article says it rates over 26 on the Taylor KO Factor so hits harder than a .300 Win Mag with half the kick. C'mon! Really? How?

Can this be for real?

 

[Tirod]

Link to more info: https://400ar.wordpress.com/

If it can use carbine gas then it can be SBR'd and suppressed.

AK/Grendel bolt, Grendel tweaked mags, and Carcano cases, custom barrel. Pistol bullets gave the top figures in performance with the caveat they are pistol bullets working out of the design envelope. Needs gel testing to see what's going on.

It seems to be the heyday of wildcats as everyone attempts to exploit the limited OAL and bolt face capacity of the AR15.

 

[eldon519]

I could be wrong, but TKO is usually applied to non-expanding bullets, so it is kind of a silly metric to compare these two with. I don't doubt the .400AR would be quite potent, but I have my doubts that it would have better terminal effect than a .300WM expanding bullet.

 

[OilyPablo]

Just when I was getting this in my budget: http://10mm-firearms.com/10mm-rifles/10mm-socom-(pic)/

 

[jim in Anchorage]

And the reason for not buying a AR10 is?

 

[R.W.Dale]

And the reason for not buying a AR10 is?

About 3 lbs


I for one feel there's plenty of room to diversify calibers and cartridges friendly for the ar15 platform. I would like to see more offerings that bridge the gap between 300blk and the real heavy hitters of the big bore single stack variety. I will be onboard for something that replicates 35rem with a case and dies that's readily available.

Look at it like this. How many "bolt action" cartridges do we have on a .473" case head alone?

 

[Casefull]

Although interesting idea it does not do anything for me. Poor down range ballistics for the short, fat bullet. My 458 socom already does what this does with admittedly less mag capacity. My 7.62 39 has much better long-range ballistics. I really think Remington did better than anyone with the ar30 and not enough folks wanted that. That is the problem with all of these 'in-between ideas', not enough shooters see the usefulness over what we already have available.

 

[jim in Anchorage]

About 3 lbs


I for one feel there's plenty of room to diversify calibers and cartridges friendly for the ar15 platform. I would like to see more offerings that bridge the gap between 300blk and the real heavy hitters of the big bore single stack variety. I will be onboard for something that replicates 35rem with a case and dies that's readily available.

Look at it like this. How many "bolt action" cartridges do we have on a .473" case head alone?

You feel 7.7 lbs is to heavy? To be Shooting .308 vs a exotic wildcat?

http://gunblast.com/SW-MP10.htm

 

[R.W.Dale]

You feel 7.7 lbs is to heavy? To be Shooting .308 vs a exotic wildcat?



http://gunblast.com/SW-MP10.htm

I like 5 to 6 lbs better.

If I wanted to be boring I don't even need an ar10 at all or any other gun beyond my 77mkII all weather in 30/06 but where's the fun in that

 

[jim in Anchorage]

I hunt sheep in some hard mountians 6-8 day trips all on foot where every oz is important. I consider 5 lbs to light.

 

[agtman]

Against hogs, the 400AR won't do anything the .300BLK can't do as well and, weight-wise, the .300 is almost identical to its 5.56mm host (i.e., same BCG, same mags).

If I want or need more power, I've got a 7.62/.308 LMT LM8. Fantastic weapon, but it does get heavy when you start adding "stuff" to it.

 

[jmr40]

An AR15 in most calibers is going to come in at around 7-7.5 lbs loaded and with optics. That is a decent weight and exactly what all of my go-to rifle chambered in 308, 30-06, and 300 WSM weigh ready to hunt. About the same weight as my scoped AR's in 5.56.

An AR10 is going to be 10-11 lbs after adding optics, ammo and any other accessories. I can carry a 10-11 lb rifle, but would prefer not to when I can get the same performance out of a 7-8 lb rifle.

 

[jim in Anchorage]

An AR15 in most calibers is going to come in at around 7-7.5 lbs loaded and with optics. That is a decent weight and exactly what all of my go-to rifle chambered in 308, 30-06, and 300 WSM weigh ready to hunt. About the same weight as my scoped AR's in 5.56.

An AR10 is going to be 10-11 lbs after adding optics, ammo and any other accessories. I can carry a 10-11 lb rifle, but would prefer not to when I can get the same performance out of a 7-8 lb rifle.

Click on my link above.

 

[CraigC]

Barking up the wrong tree. Firstly, TKO does not apply to high velocity rifle cartridges. It's a misapplication of the concept and yields nothing useful.

This is nothing new. JD Jones did the same thing by necking down the .454. He discovered the obvious, existing pistol bullets are too tender for the purpose.

I can tell you what will happen with existing pistol bullets, they're going to explode when they hit, if they survive the trip at all. I've tested several .40/10mm bullets in a .38-40 rifle and with only a few hundred feet per second over their design envelope, they expand VERY rapidly. The 180gr Gold Dot flattens out the size of a quarter when launched at 1475fps. The 135gr Sierra explodes like a varmint bullet at 1600fps.

Those 200gr bullets they're using in the article are better but still light in the loafers for big game.

What would be needed is a heavily constructed controlled expansion design of about 220-240gr at ~2000fps. Then you would have something. So if existing bullets cannot be used, what's the point???

 

[OilyPablo]

I often wonder the same thing, even for my 10mm AR. Any plated bullet us useless. The HAP bullets are decent. But those really high velocities may need solids. Such as copper or another alloy.

 

[redneck2]

I have an AR in .358 WSSM. Shoots flat enough to take deer to 300 yards. Uses real live rifle bullets. 200 grains at about 2,700-2,800 fps

 

[panatomicx]

That's some fantastic performance. Your AR an AR-10? Because I reckon a 358 WSSM cartridge delivering 2800 FPS with a 200 grain bullet would have to be at least 65,000 PSI. A 358 Winchester with that capacity doesn't get much more than 2500 FPS and it's rated at 50K. A word of caution: oversized chambers in the AR-15 are usually limited to 35,000 PSI.

Hunting deer usually doesn't need more than a couple of shots, so a single stack is ok. But if you've ever been in the middle of a herd of hogs in the brush, you'd want as many rounds as legal, which is why the 400AR came along. It can hold up to 25 and is rated at 50,000 PSI.

 

[Casefull]

That's some fantastic performance. Your AR an AR-10? Because I reckon a 358 WSSM cartridge delivering 2800 FPS with a 200 grain bullet would have to be at least 65,000 PSI. A 358 Winchester with that capacity doesn't get much more than 2500 FPS and it's rated at 50K. A word of caution: oversized chambers in the AR-15 are usually limited to 35,000 PSI.

I agree. Maybe it was a 24 inch barrel. Think of what you would need to get a 308 of 200g up to 2800 fps. I wonder how much powder was in the case to get that velocity?

 

[crazysccrmd]

That's some fantastic performance. Your AR an AR-10? Because I reckon a 358 WSSM cartridge delivering 2800 FPS with a 200 grain bullet would have to be at least 65,000 PSI. A 358 Winchester with that capacity doesn't get much more than 2500 FPS and it's rated at 50K. A word of caution: oversized chambers in the AR-15 are usually limited to 35,000 PSI.

Hunting deer usually doesn't need more than a couple of shots, so a single stack is ok. But if you've ever been in the middle of a herd of hogs in the brush, you'd want as many rounds as legal, which is why the 400AR came along. It can hold up to 25 and is rated at 50,000 PSI.

The WSSMs use a completely different bolt and barrel extension. They don't have the low pressure limitations of rounds like the 450B, 458S, etc, that use a standard bolt with the face opened up. A 358 WSSM, depending on version, has the same case capacity as a 358 Win.

 

[panatomicx]

Against hogs, the 400AR won't do anything the .300BLK can't do as well and, weight-wise, the .300 is almost identical to its 5.56mm host (i.e., same BCG, same mags).

If I want or need more power, I've got a 7.62/.308 LMT LM8. Fantastic weapon, but it does get heavy when you start adding "stuff" to it.

Whenever the .300 AAC Blackout comes up for hogs, I always think about the time my brother was mauled after shooting a 350 lb boar three times with his .30 Carbine. It was lucky he'd fired three rounds, because his friend up the trail thought he was in trouble (three evenly spaced shots being the universal call for help) and he was. His buddy found him unconscious, bleeding out, with the pig long gone. After hospitalization and several months later, he went back to the same place, knocked it down with a single shot from his Springfield .30'06.

The .300BLK is ballistically superior to the .30 Carbine, but I still think of that experience when considering what to take. I love my .300 WSM, great for deer and elk, but it's a bolt gun, not so fast on the followup when hunting hogs. The 400AR produces 75% more power than the 300 AAC Blackout - a thousand foot-pounds more with a bigger, heavier bullet.

 

[agtman]

The .300BLK is ballistically superior to the .30 Carbine, but I still think of that experience when considering what to take. I love my .300 WSM, great for deer and elk, but it's a bolt gun, not so fast on the followup when hunting hogs. The 400AR produces 75% more power than the 300 AAC Blackout - a thousand foot-pounds more with a bigger, heavier bullet.

Sorry to hear that about your brother, but a 220gn subsonic OTM bullet fired from my 10.5" .300BLK (suppressed) isn't even in the same universe as a piddly 110gn pellet from a .30 Carbine pea-shooter - and 200gn-220gn .300 BLK loads have been killing hogs every day all over the USA for ... what?, like the last 8-years?

 

[crazysccrmd]

I'll take a 110gr hunting bullet in a 30 Carbine over a 220gr match bullet in a 300BO any day. A subsonic match bullet is a poor choice for a hunting load. A hard cast 220gr 40 caliber bullet at twice that speed is far and away superior.

 

[CraigC]

The 400AR produces 75% more power than the 300 AAC Blackout - a thousand foot-pounds more with a bigger, heavier bullet.

Which does you no good if the bullet doesn't hold up. Which they don't.

 

[R.W.Dale]

Which does you no good if the bullet doesn't hold up. Which they don't.

One word

Cast


I also believe there are tough .400 diameter bullets intended for 45 caliber muzzleloaders. So this whole there's no bullets assertion is a red herring

ETA just one example
https://www.midwayusa.com/product/1...with-45-caliber-sabot-box-of-50-bulk-packaged

 

[agtman]

Which does you no good if the bullet doesn't hold up. Which they don't.

Correct.

In terms of projectiles, the .300BLK is using .308 rifle bullets that have a proven record of performance on hogs, deer, et. al., whether at supersonic or subsonic velocities.

No doubt hard-cast boolits are effective too, but those aside, pistol bullets fired at rifle velocities typically under-perform.