Whats the most powerful round I can put in an AR-10 build?

[MoHobbyPlinker]

I was having a discussion with my brother and it was about how his AR-10 .300 BLK would do in what I would call a backwoods shooting competition against my 6.5 cm Sig Cross. They are set up for very different things. He wants his as a 300 yd subsonic shooter with a can to shoot things without being noticed. I am trying to set up my Cross to be a precision rifle shooting 700 yds.

His thought was he wants a gun that can throw as much lead down field with more force than a 5.56 but at subsonic speeds with a can to further help stay hidden if the need arose.

This got me thinking, what is the most powerful round I could put on an AR-10 frame in a semi auto form and still be able to stay subsonic, shoot 400 yds, and stay on target between shots for 10 rounds.

Can a 50 BMG be put in a semi auto form? Would it totally blow out a shoulder? Is the tried and true .308/7.62x51 the best for the what he is going for?

 

[redhooker]

40mm m203…

Most likely exactly what you want.

 

[B y r o n]

If you want a 50 cal semi-auto take a look at the

Barrett M82 A1 50BMG Semi Automatic Rifle​

300 blackout is based on the AR-15 platform and not AR-10. Both the 300 BO and 308/7.62x51 can shoot sub-sonic as well as high velocity loads.

 

[camocorvette]

Let's think critically. Can a 50 bmg fit in a AR10 pattern rifle?

 

[hlee]

If he has a 300 Bo in an ar10, he’s doing it wrong.

With a subsonic cartridge, you are limited by the speed of sound, and the only way to add more “thump” down range is with more mass.

50 Beowulf. 458 socom. Both run in an ar15.

8.6blk runs in an ar10.

You can launch 220 grain bullets from a 300bo out of an ar15 at subsonic velocities. A 308 in an ar10 does not make sense give a subsonic restriction.

No, you cannot (easily, or semi automatically) run a 50 BMG in an ar15 or ar10.

 

[sirhrmechanic]

View attachment 8071571

Let's think critically. Can a 50 bmg fit in a AR10 pattern rifle?

I’d have to check, but I think my Barrett M82 will chamber an entire AR-10.



Sirhr

 

[MoHobbyPlinker]


Let’s think critically. Can a 50 bmg fit in a AR10 pattern rifle?
- Lol thanks. I don’t know any better. Not sure what can go on an AR-15, what can go on an AR-10, or otherwise.


If he has a 300 Bo in an ar10, he’s doing it wrong.
- I’m probably wrong, it is probably an AR-15.

With a subsonic cartridge, you are limited by the speed of sound, and the only way to add more “thump” down range is with more mass.

50 Beowulf. 458 socom. Both run in an ar15.
- 50 beowolf is what I meant, not 50 BMG

8.6blk runs in an ar10.

You can launch 220 grain bullets from a 300bo out of an ar15 at subsonic velocities. A 308 in an ar10 does not make sense give a subsonic restriction.

No, you cannot (easily, or semi automatically) run a 50 BMG in an ar15 or ar10.

 

[Aftermath]

 

[BCP]

I believe there’s a 45/70 AR10.

 

[hlee]

I believe there’s a 45/70 AR10.

45/70 auto. I’m pretty sure it is a rimless cartridge based in the 45/70. That rim really makes mag feeding ‘normal’ 45/70govt a pain in the dick. I’ve never seen 45/70 auto in a store. For someone that is as new as the OP, I’d steer clear of wildcats…

 

[hlee]

I believe 300 saum is still the biggest round you can get in there.

But if you are constraining the discussion to subsonic rounds (as the OP did), is there any reason? How much bigger than a 220grain can you get in a 30 cal bullet? A 300bo does fine with them at subsonic speeds.

 

[camocorvette]

"50 beowolf is what I meant, not 50 BMG"
Mohobby,

There's a pic from the web. Ar10 could do 7-08, . 338 Federal and some others.
Ar15 yeah beowolf and similar.

Technically you can run 50bmg on a ar15 lower.

.50 bmg uppers, yes or no?

I've been interested in possibly buying a .50 bmg. I read an article recently about the uppers that can convert your AR into a .50. Does anyone know anything about these weapons systems, or has anyone ever fired one? I wouldn't want to put one on any of my lowers, I would want a dedicated...

www.snipershide.com

That pretty much will catch you up on that.

 

[MoHobbyPlinker]

Thanks for the input lol

 

[wvfarrier]

KAK Industries makes a 300WSM upper for the AR10

 

[MoHobbyPlinker]

"50 beowolf is what I meant, not 50 BMG"
Mohobby, View attachment 8071674

There's a pic from the web. Ar10 could do 7-08, . 338 Federal and some others.
Ar15 yeah beowolf and similar.
View attachment 8071676

Technically you can run 50bmg on a ar15 lower.

.50 bmg uppers, yes or no?

I've been interested in possibly buying a .50 bmg. I read an article recently about the uppers that can convert your AR into a .50. Does anyone know anything about these weapons systems, or has anyone ever fired one? I wouldn't want to put one on any of my lowers, I would want a dedicated...

www.snipershide.com

That pretty much will catch you up on that.

Thank you for the info, this does help a lot. The mag size is what made me think that anything bigger than a .308 would have to go on an AR-10 lower due to the size of the ammunition

 

[SupressYourself]

This got me thinking, what is the most powerful round I could put on an AR-10 frame in a semi auto form and still be able to stay subsonic, shoot 400 yds, and stay on target between shots for 10 rounds.

You'll be challenged to shoot anything subsonic to 400 yards. Since you're limited to (about) 1125 FPS, those bullets drop like a rock.
For example, assuming a 100 yard zero, a 220gr 30 cal bullet would need about 45 MOA of elevation to drop in there. That's roughly what it takes my 6.5 Creed to get to 1350 yards.

 

[sboone]

I believe there’s a 45/70 AR10.

There is a rimless 500 S&W, the 500 Automax. It's about the only round you can get in an AR-10 frame that will let you get 700 grains of lead moving down range in 1 trigger pull.

AR500 - 500 Auto Max - Big Horn Armory

The most powerful short range semi-auto in the world by Big Horn Armory! Based on an AR 308 platform, it is capable of putting 50 BMG power on target.

www.bighornarmory.com

 

[Nbleak21]

Putting ten rounds on target, with any subsonic round, at 400 yards is going to be challenging.
As much as @redhooker was joking about M203, it probably would be more effective, at least in satellite-clear skies.

The challenge with subs is that, like everything else, they fall at the rate of gravity.
Since they fly slower, they fall more over a given distance.
This is because they take much longer to get there.

Let's first talk about Flight time for each round:
Let's ignore everything but velocity for a minute to compare two rounds:
AR-10 Round shooting a standard cartridge, IE 6.5CM or 308.
Either can be had shooting velocities of ~2700fps

AR-10 shooting 8.6BLK or AR-15 shooting 450BM subs (these would be my choices in their respective platforms.
Either can be shot at velocities around 900fps (to ensure they don't break the sound barrier, remaining subsonic)

400 yards = 1200ft
A 308 or 6.5 Creedmoor will impact the target in ~0.45 seconds from pulling the trigger (1200ft / 2700fps)
An 8.6BLK or 540BM will impact the target in ~1.34 seconds from pulling the trigger (1200ft / 900fps)

So the first challenge with Subs is that whatever target is out there has to stay still, or any movement be accounted for, for an additional 0.9 seconds.
If you're talking about a SHTF, hunting, or any other potential target movement situation, many things can happen in that additional .9 seconds.

So now let's talk bullet drop:
Note: Calculations were performed using a free fall calculator found via google.

Free Fall Height Calculator

Our free fall height calculator can help you calculate the height an item travels through during a free fall.

www.omnicalculator.com

It's been far, too long since I've taken physics to math it out in my head

at 0.45 seconds, each projectile will have dropped ~40" due to gravity.
with the above 308 or 6.5cm round, that can be adjusted for with the scope/sights, or aim that much higher, and you've got an impact.

for the subsonic round, you're still only ~1/3 of the way to the target, and you've already dropped ~40" due to gravity.
With either subsonic round, your bullet will have fallen ~346"! That's 28ft, or darn near, a 3-story building!
So, you'll have to aim much higher to impact your target AND have that longer flight time.

In conclusion:
Your bro must be a rockstar shooter to stack impacts at 400 yards.
Quiet is nice, but at what cost? Speed, Margin of Error, moving target compensation?

Run a 308 or 6.5, with a can, and you'll reign supreme in >95% of scenarios against a subsonic beyond 100yds, all else being equal...
Or, as @redhooker was saying: get an M203 and absorb that margin of error with a real thumper!

 

[BCP]

There is a rimless 500 S&W, the 500 Automax. It's about the only round you can get in an AR-10 frame that will let you get 700 grains of lead moving down range in 1 trigger pull.

AR500 - 500 Auto Max - Big Horn Armory

The most powerful short range semi-auto in the world by Big Horn Armory! Based on an AR 308 platform, it is capable of putting 50 BMG power on target.

www.bighornarmory.com

Someone needs to make a 75 caliber AR upper. The "Brown Bessed". Greatest most stupendoused tactical subsonic cartridge ever!

 

[hlee]

Someone needs to make a 75 caliber AR upper. The "Brown Bessed". Greatest most stupendoused tactical subsonic cartridge ever!

Firearms (though not shotguns) over 50 cal are defined as destructive devices. Muzzle loaders are not defined as firearms, so are not defined as destructive devices.

 

[MoHobbyPlinker]

Putting ten rounds on target, with any subsonic round, at 400 yards is going to be challenging.
As much as @redhooker was joking about M203, it probably would be more effective, at least in satellite-clear skies.

The challenge with subs is that, like everything else, they fall at the rate of gravity.
Since they fly slower, they fall more over a given distance.
This is because they take much longer to get there.

Let's first talk about Flight time for each round:
Let's ignore everything but velocity for a minute to compare two rounds:
AR-10 Round shooting a standard cartridge, IE 6.5CM or 308.
Either can be had shooting velocities of ~2700fps

AR-10 shooting 8.6BLK or AR-15 shooting 450BM subs (these would be my choices in their respective platforms.
Either can be shot at velocities around 900fps (to ensure they don't break the sound barrier, remaining subsonic)

400 yards = 1200ft
A 308 or 6.5 Creedmoor will impact the target in ~0.45 seconds from pulling the trigger (1200ft / 2700fps)
An 8.6BLK or 540BM will impact the target in ~1.34 seconds from pulling the trigger (1200ft / 900fps)

So the first challenge with Subs is that whatever target is out there has to stay still, or any movement be accounted for, for an additional 0.9 seconds.
If you're talking about a SHTF, hunting, or any other potential target movement situation, many things can happen in that additional .9 seconds.

So now let's talk bullet drop:
Note: Calculations were performed using a free fall calculator found via google.

Free Fall Height Calculator

Our free fall height calculator can help you calculate the height an item travels through during a free fall.

www.omnicalculator.com

It's been far, too long since I've taken physics to math it out in my head

at 0.45 seconds, each projectile will have dropped ~40" due to gravity.
with the above 308 or 6.5cm round, that can be adjusted for with the scope/sights, or aim that much higher, and you've got an impact.

for the subsonic round, you're still only ~1/3 of the way to the target, and you've already dropped ~40" due to gravity.
With either subsonic round, your bullet will have fallen ~346"! That's 28ft, or darn near, a 3-story building!
So, you'll have to aim much higher to impact your target AND have that longer flight time.

In conclusion:
Your bro must be a rockstar shooter to stack impacts at 400 yards.
Quiet is nice, but at what cost? Speed, Margin of Error, moving target compensation?

Run a 308 or 6.5, with a can, and you'll reign supreme in >95% of scenarios against a subsonic beyond 100yds, all else being equal...
Or, as @redhooker was saying: get an M203 and absorb that margin of error with a real thumper!

This is great. Thank you. My brother is shooting his 300 blk unsuppressed right now out to 200 yds. He would like to suppress and go out to 300. Cant say how well he will do with it. We arent ones to do the math either. We are just dumbasses going "wonder how well this will work"
We were discussing our different strategies to our guns and while i could shoot him from 500-700 yds. His theory is he can hide in brush and the thicket unseen until his opposition is within 300yds and take them out without being seen or heard and he would rather have the semi auto over a bolt for the quicker repeat shots so if he did miss he could shoot again without moving a bunch to get the next bullet in the chamber.

These scenarios will obviously never come to fruition just a fun discussion. To fill out this scenario, out younger brother has now become out zombie/enemy bait to draw out our targets while we sit at a distance lol

 

[HOOFER]

You'll be challenged to shoot anything subsonic to 400 yards. Since you're limited to (about) 1125 FPS, those bullets drop like a rock.
For example, assuming a 100 yard zero, a 220gr 30 cal bullet would need about 45 MOA of elevation to drop in there. That's roughly what it takes my 6.5 Creed to get to 1350 yards.

Tell that to the sharps rifle crowd circa 1850s ….. or current day at the Quigley..

 

[AMMOWASTER]

Firearms (though not shotguns) over 50 cal are defined as destructive devices. Muzzle loaders are not defined as firearms, so are not defined as destructive devices.

Not all of them but I doubt you could get an exemption for a semi auto.

 

[lil'skeet]

I was having a discussion with my brother and it was about how his AR-10 .300 BLK would do in what I would call a backwoods shooting competition against my 6.5 cm Sig Cross. They are set up for very different things. He wants his as a 300 yd subsonic shooter with a can to shoot things without being noticed. I am trying to set up my Cross to be a precision rifle shooting 700 yds.

His thought was he wants a gun that can throw as much lead down field with more force than a 5.56 but at subsonic speeds with a can to further help stay hidden if the need arose.

This got me thinking, what is the most powerful round I could put on an AR-10 frame in a semi auto form and still be able to stay subsonic, shoot 400 yds, and stay on target between shots for 10 rounds.

Can a 50 BMG be put in a semi auto form? Would it totally blow out a shoulder? Is the tried and true .308/7.62x51 the best for the what he is going for?

Here is 50 bmg in an AR 15 lower.

.50 BMG Upper Receivers

The best .50 BMG upper receivers, bolt-action,single-shot and magazine-fed for AR-15 lowers

www.mccutchenfirearms.com

 

[BullGear]

The Beowulf runs in an AR15 lower. It's a good round, particularly if you're hunting pigs. Will thump them good. There are a few companies that make a 50 BMG upper that can be mated to an AR15 lower. I don't know of anyone making uppers for these 2 rounds that work with the AR10. BTW, they say that 50B is comparable to a 45/70 round.

 

[BullGear]

Here is 50 bmg in an AR 15 lower.

.50 BMG Upper Receivers

The best .50 BMG upper receivers, bolt-action,single-shot and magazine-fed for AR-15 lowers

www.mccutchenfirearms.com

That looks surprisingly like the Safety Harbor SHTF uppers. They too make a descent upper. At one time they also made a purpose built lower. This lower is exactly the same as an AR15, but it doesn't have the mag well milled out.

 

[AMMOWASTER]

There is a rimless 500 S&W, the 500 Automax. It's about the only round you can get in an AR-10 frame that will let you get 700 grains of lead moving down range in 1 trigger pull.

AR500 - 500 Auto Max - Big Horn Armory

The most powerful short range semi-auto in the world by Big Horn Armory! Based on an AR 308 platform, it is capable of putting 50 BMG power on target.

www.bighornarmory.com

That's probably the answer for the weird question. I don't think they sell just an upper unfortunately though so you have to buy a whole gun. If I could buy just a barrel and bolt/BCG the cost of entry would be a lot lower. There are also 45 Raptor which is a similar idea but based on the 460. Same guys then did the 375 Raptor which might work and has some heavy target bullets available.

 

[AMMOWASTER]

That looks surprisingly like the Safety Harbor SHTF uppers. They too make a descent upper. At one time they also made a purpose built lower. This lower is exactly the same as an AR15, but it doesn't have the mag well milled out.

I bought the complete gun on a Black Friday deal. Super light. Little crude but at the time was hard to beat value wise.

 

[kthomas]

Silly thread, but this reminds me of the time when McCann Industries made some .458 Win mag M1 Garands.

The Firearm Blog - Firearms not Politics

Firearms not Politics

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[HOOFER]

Silly thread, but this reminds me of the time when McCann Industries made some .458 Win mag M1 Garands.

The Firearm Blog - Firearms not Politics

Firearms not Politics

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You don’t gotta penetrate a plate if you collapse their rib.

If it works it isn’t stupid

 

[roostercogburn98]

I think OP should just start jamming rounds into an ar platform until he finds one that won’t work.


Then we will all have the answer

 

[carbonbased]

We were discussing our different strategies to our guns and while i could shoot him from 500-700 yds. His theory is he can hide in brush and the thicket unseen until his opposition is within 300yds and take them out without being seen or heard and he would rather have the semi auto over a bolt for the quicker repeat shots so if he did miss he could shoot again without moving a bunch to get the next bullet in the chamber.

Just counter with, “I have a thermal and you don’t so you’re dead.”

 

[232593]

VA silent Arsenal does one in 6.5 WSM. Problem is you can’t run the high BC projectiles due to mag length.

I’m told these guys make decent ARS in the calibers you seek. Never fired one myself

Custom AR10 Rifles Accuracy Systems Gunsmith Gunsmithing AR 10

AR10 Rifles customized by Accuracy Systems Inc. ASI does custom gunsmithing, builds Custom Rifles and rifle Rebarreling on AR10 rifles.

www.ar-10-rifles.com

 

[232593]

Vigilance Rifles does a really, really heavy.50 BMG semi auto and a reasonable weight .408 semi auto. Not ARs though.

 

[wvfarrier]

VA silent Arsenal does one in 6.5 WSM. Problem is you can’t run the high BC projectiles due to mag length.

I’m told these guys make decent ARS in the calibers you seek. Never fired one myself

Custom AR10 Rifles Accuracy Systems Gunsmith Gunsmithing AR 10

AR10 Rifles customized by Accuracy Systems Inc. ASI does custom gunsmithing, builds Custom Rifles and rifle Rebarreling on AR10 rifles.

www.ar-10-rifles.com

The problem is the mag length restrictions. None of those can really take advantage of "long" better bc projectiles. I love the idea of a 300wsm but we end up being restricted due to the mag length

 

[Romeo458]

Introducing the 45 RAPTOR Cartridge for the AR-10 -

Master cartridge designer Arne Brennan, the original inventor of the concept that became the 6.5mm Grendel, has developed a new round for the AR-10 platform. The 45 RAPTOR case is a necked up .308 Winchester case with a case length and body dimensions of a .460 S&W. It packs a much greater punch...

www.thefirearmblog.com

You're welcome

 

[hlee]

Funny how everyone jumps to the saum and wsm when the OP specifically stared “for shooting subsonic bullets.” They bring nothing to the table in that application…

 

[AMMOWASTER]

Funny how everyone jumps to the saum and wsm when the OP specifically stared “for shooting subsonic bullets.” They bring nothing to the table in that application…

In bolt guns some guys chopped cases and made a 50WSM and shot BMG bullets. That would be awesome in an AR10 but I can't find a lot of info on it.

 

[babyguppy]

I’d have to check, but I think my Barrett M82 will chamber an entire AR-10.



Sirhr

I know for a fact, that a 300 Win Mag will chamber and fire in a 338LM.

 

[sirhrmechanic]

I know for a fact, that a 300 Win Mag will chamber and fire in a 338LM Once.

FIFY.

Sirhr

 

[hlee]

In bolt guns some guys chopped cases and made a 50WSM and shot BMG bullets. That would be awesome in an AR10 but I can't find a lot of info on it.

A 700 grain bullet at 1000 fps would put a thwackin’ on a pig…

 

[hlee]

FIFY.

Sirhr

Probably no worse, or not much worse, than firing a 300 win mag in a 300 weatherby mag. I’ve seen a number of cases with that tell tale sign at the local range on the weekend before deer season..

 

[sirhrmechanic]

Probably no worse, or not much worse, than firing a 300 win mag in a 300 weatherby mag. I’ve seen a number of cases with that tell tale sign at the local range on the weekend before deer season..

When is someone going to create a wildcat and just call it .300 Fudd?

I mean we have the 6.5 Gay Tiger... Someone needs to do some kind of 'hot rod' .30-30 and call it the .30 Fudd. Where is @Geno C. when you need him?

Sirhr

 

[hlee]

When is someone going to create a wildcat and just call it .300 Fudd?

I mean we have the 6.5 Gay Tiger... Someone needs to do some kind of 'hot rod' .30-30 and call it the .30 Fudd. Where is @Geno C. when you need him?

Sirhr

30Fudd? Isn’t that a 270win necked up to 30 cal?

 

[Huskydriver]

When is someone going to create a wildcat and just call it .300 Fudd?

I mean we have the 6.5 Gay Tiger... Someone needs to do some kind of 'hot rod' .30-30 and call it the .30 Fudd. Where is @Geno C. when you need him?

Sirhr

Already been done... It's called the .30-06......

 

[AMMOWASTER]

A 700 grain bullet at 1000 fps would put a thwackin’ on a pig…

Yup or anything else. I really want to see a 50 Blackout that's standardized. Not near as fun now that 50bmg bullets aren't cheap. Should have grabbed a few thousand when they were under $.25 a piece. Lot's of cool possibilities with big dedicated 50 cal subs.

 

[sirhrmechanic]

Already been done... It's called the .30-06......

Sirhr

 

[sirhrmechanic]

30Fudd? Isn’t that a 270win necked up to 30 cal?

I see what you did there...

Sirhr

 

[carbonbased]

FIFY.

Sirhr

Probably no worse, or not much worse, than firing a 300 win mag in a 300 weatherby mag. I’ve seen a number of cases with that tell tale sign at the local range on the weekend before deer season..

So what happens in these two mistakes? And what do the cases look like? Just curious.

 

[DocRDS]

Silly thread, but this reminds me of the time when McCann Industries made some .458 Win mag M1 Garands.

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