Other AR-15 Calibers

Boxcab · Jan 26, 2009

Can someone edjumakate me on the other calibers that will feed through my standard AR-15 lower when the appropriate upper is attached? I'm looking for alternatives to the .223/5.56. What caliber is the most painless to transition to? (Uses std AR mags, etc.)

Thanks,

Boxcab

eddiek2000 · Jan 26, 2009

Not standard mags, but looks good:

http://www.brownells.com/aspx/NS/store/productdetail.aspx?p=27008&mc_ID=3020

Redneck · Jan 26, 2009

Pistol calibers:

7.62x25mm Tokarev
9x19mm Parabellum
10mm Auto
.40 S&W
.45 ACP
5.7x28mm
.50 Action Express

Rifle calibers:

.17 Remington
.17 Remington Fireball
.22 Long Rifle
.20 Tactical
.204 Ruger
.221 Remington Fireball
.222 Remington
.222 Remington Magnum
5.45x39mm
5.56x45mm NATO
.223 Remington
.223 WSSM
6 mm PPC
6mm-223 Remington
.243 WSSM
6.5 mm Grendel (.264 cal)
6.8 mm Remington SPC (.270 cal)
.30 Remington AR
.300 Whisper
7.62x39mm
.450 Bushmaster
.458 SOCOM
.50 Beowulf

SCARCQB · Jan 26, 2009

Wow Red,

can you recite all those calibers with just one breath? Just kidding, but I think thats all of them.

there is also a 410 shotgun conversion, only available in europe.

bluecollarkid · Jan 26, 2009

Remington has 7mm-08 AR rifles

Redneck · Jan 26, 2009

Id almost like a 17HMR AR

FIREHAWK · Jan 26, 2009

don't forget 5.56 golfball launcher

http://www.cowtownshooters.com/

Bigdtc · Jan 26, 2009

Hmmm, Does anyone make 7.62x25 uppers? I would consider an AR if they did.

smokey · Jan 26, 2009

7.62x25 upper!? sweeeeeet

4g64loser · Jan 26, 2009

available, cannot remember who made it. only seen one once. on an M16 lower, it was a sight to behold. I'd love to have one. beats 9mm any day of the week.

boricuamaximus · Jan 26, 2009

I love the 6.8. It's the rifle I will use for hunting this season. I am really thinking of getting the 5.7x28 upper just for kicks and so my son can shoot an EBR.

http://www.57center.com/m8_view_item.html?m8:item=AR57-100

BenL · Jan 26, 2009

Here's my .50 Beowulf...

BeltBuckle · Jan 26, 2009

Benlineberry said:
Here's my .50 Beowulf...

LOL

that's one sweet lookin giant killer!

fivepointstar · Jan 26, 2009

no 7.62x54r???

E.Shell · Jan 26, 2009

bluecollarkid said:
Remington has 7mm-08 AR rifles

The 7-08 and other .308 family members will be in an AR10 platform.

fivepointstar said:
no 7.62x54r???

Too long, too much rim.

Boxcab · Jan 27, 2009

Thanks all,

I'm looking for something with a little more punch. The Beowulf looks great!

Of the following, what caliber is most compatible with a standard AR-15 lower and magazines?

6.5 mm Grendel
6.8 mm SPC
7.62x39mm
.450 Bushmaster
.458 SOCOM
.50 Beowulf

How do the ballistics compare? Availability of ammo or reloading components?

Basicly, what is the Practicality level of each?

Thanks again for bring me up to speed,

-Boxcab

Redneck · Jan 27, 2009

I posted this in the .280 Semi-Automatic thread theres a little more info there too.http://www.mdshooters.com/showthread.php?t=14089&highlight=.280

6.5 is a better round than 6.8 IMO. I looked at the 6.8 round bc like you said, its almost a .270. But when I compared the ballistics between the 6.8 and a .270, they were completely different. 6.8 is slower and has much less energy than a .270.

Ive always wanted to chamber an AR in a round that had similar ballistics to a .270. Unfortuantly you get either energy or accuracy. Sure the 50 beuwolf has a lot of energy at 100 yards, but is dropping like a soft ball.

The 6.5 grendel seems to be a very fast and flat round, but it just doesnt have the muzzle energy or energy at 100 yards that id like to have.

From the muzzle the 6.5 with a 123 grain bullet has 2065 foot pounds of energy going 2750 fps, at 100 yards it has 1829 foot pounds of energy going 2588 fps, and at 200 yards it has 1615 foot pounds of energy going 2432 fps with a 2.7" drop if zeroed at 100 yards. Thats a little more energy and less velocity than a .243 shooting 95 grain Winchester Ballistic Silvertips.

From the muzzle a 6.8 with a 115 grain bullet has 2002 foot pounds of energy going 2800 fps, at 100 yards it has 1647 foot pounds of energy going 2540 fps, and at 200 yards it has 1343 foot pounds of energy going 2293 fps with 2.91'' drop if zeroed at 100 yards. Thats even slower and has less energy than the same .243 round mentioned above.

The .280 round that you are looking at from the muzzle shoots over 3000 fps and has around 2800 foot pounds of energy. At 100 yards your looking at around 2800 fps and 2500 foot pounds of energy. At 200 yards the round is traveling about 2650 fps with 2200 foot pounds of energy and a drop of about 2.8" if zeroed at 100 yards.

The way I see it is we can't get what we want, looks like we will have to settle for less or buy something in the AR 10 platform.

Hope this helps

Check this site for other caliber ideas http://www.accuracysystemsinc.com/ar15_conversion.php

canuck · Jan 27, 2009

Box

I have both the 6.8 and the Grendel. If I were you I would opt for the 6.5. AMMOMAN has great deals on the ammo now. $10/box delivered. Just got a case.

Neither the 6.8 nor the 6.5 use "standard" 5.56 mags. The internal geometry is different to account for the positioning of the shoulder on those 2 rounds. C Products makes excellent Stainless teflon coated mags in both calibers. I have dozens of them and they work flawlessly. They are in stock at c products.

Attached is a comparative ballistics table that compares the 5.56, 7.62x51, 6.8, and 6.5. Some of the conclusions that RED posted, I just dont agree with. When you are looking at the point where a round has <500ft/lbs of energy the grendel is far superior to 5.56 and 6.8. It has plenty of energy. Using a standard AR reciever - the grendel is about as good as it gets.

BTW - you will also need to change the bolt head to go with 6.8 or 6.5.

BenL · Jan 27, 2009

Boxcab said:
Thanks all,

I'm looking for something with a little more punch. The Beowulf looks great!

Of the following, what caliber is most compatible with a standard AR-15 lower and magazines?

6.5 mm Grendel
6.8 mm SPC
7.62x39mm
.450 Bushmaster
.458 SOCOM
.50 Beowulf

How do the ballistics compare? Availability of ammo or reloading components?

Basicly, what is the Practicality level of each?

Thanks again for bring me up to speed,

-Boxcab

The SOCOM and Beowulf use factory standard 5.56 mags. Beowulf suggests that you bend the feed lips out slightly, but I never have, and haven't had a problem. I actually use Pmags for it without issues.

They are all equally compatible with the lower. I guess it depends what you want to do with it. The beowulf is ballistically similar to the .45-70. With the right load, it's good for hogs, deer and moose- it's a thumper.
I hear the Grendal is a good distance round (don't know... don't have one). What are you going to do with it?

If you're looking for "practical", stick with 5.56. Most of the ammo you've listed (except the 6.8SPC & 7.62) is expensive and/or hard to get. Since Nov. 4, Beowulf ammo that used to sell for $25 a box and was readily available, is getting upwards of $70 a box on gunbroker and hard to find.

canuck · Jan 27, 2009

Ben

Take a look at the .pdf I posted. The Grendel is THE distance round in standard AR lowers. I have mine set up with a 2.5x10 Night force. It's my 350 - 800yd choice.

The Beo is a beast and a great short range thumper. I've attached the Beo ballsitic tables - if you don't already have them.

Other AR-15 Calibers

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