FlynnCastle
Member
I currently own an AR-15 chambered in 5.56mm, m4gery style. Basically wondering if 6.8 mags fit in the standard 5.56 mag well. Has anyone ever tried this? Can I just swap out upper receivers? Or do I have to get a whole new gun?
Switching an AR-15 from 5.56mm to 6.8spc
- Thread starter FlynnCastle
- Start date
- Status
mljdeckard
Member
Yes, they fit. And yes, you can pop a different upper on and start shooting. (Isn't this fun? Why did it take them so long to THINK of this stuff!?)
Cal-gun Fan
Member
Yes, the mags fit in the same magwell.
You can just swap out upper receivers.
First though, remember that 6.8 is not cheap, or easy to find. Usually, you are paying .80 cents a round, which can add up very quick.
You can just swap out upper receivers.
First though, remember that 6.8 is not cheap, or easy to find. Usually, you are paying .80 cents a round, which can add up very quick.
Shawn Dodson
Member
- Joined
- Dec 28, 2002
- Messages
- 3,198
To convert from 5.56 to 6.8 requires a minimum of three components:
1) 6.8 barrel
2) 6.8 bolt
3) 6.8 magazine
The easiest method is to purchase a complete 6.8 upper receiver assembly (with bolt carrier group) and swap it with the 5.56 upper receiver.
I don't know of any polymer magazines available for 6.8. All of those I know of are metal.
1) 6.8 barrel
2) 6.8 bolt
3) 6.8 magazine
The easiest method is to purchase a complete 6.8 upper receiver assembly (with bolt carrier group) and swap it with the 5.56 upper receiver.
I don't know of any polymer magazines available for 6.8. All of those I know of are metal.
6.8 SPC is not a military surplus caliber, therefore some think it's outrageously expensive and difficult to get. In reality, you can internet order and ship direct to your house a wide variety of loads, and they will be the same or less than most normal hunting ammo price.
SSA has it for $18 a box, compared to Leverevolution .30-30 for $24.98 at Academy or other Boxmart. So it's really a matter of informed perspective.
What were some people thinking, it was taxpayer supported ammo with surplus coming out of storage after 20 years, made in the millions? Really? Dirt cheap for ammo, no, and it was never promised or intended. You can't sell new loads in brass cases for less than cost. Anyone complaining about it is obviously underinformed about business reality. They are apparently thinking all ammo should be the same price just because it loads into an AR?
Treat it like like hunting ammo, it's competitive, and offers 40% more power than 5.56. It's also legal in states 5.56 may not be. It's a good round out to 400m, which is exactly what the inventors intended. It's the #1 alternative caliber, and will probably stay that way and grow even more over the next five years, precisely because it amplifies all the good stuff about the AR.
You can find ammo, it's not horribly expensive, and you can likely afford a box or two for hunting every year. Even cheaper if you reload, which is what real shooters do when dedicated to it, like shotgunners or .45ACP.
Just don't fall into the naive trap of thinking it's the same as surplus. Not yet, if ever.
SSA has it for $18 a box, compared to Leverevolution .30-30 for $24.98 at Academy or other Boxmart. So it's really a matter of informed perspective.
What were some people thinking, it was taxpayer supported ammo with surplus coming out of storage after 20 years, made in the millions? Really? Dirt cheap for ammo, no, and it was never promised or intended. You can't sell new loads in brass cases for less than cost. Anyone complaining about it is obviously underinformed about business reality. They are apparently thinking all ammo should be the same price just because it loads into an AR?
Treat it like like hunting ammo, it's competitive, and offers 40% more power than 5.56. It's also legal in states 5.56 may not be. It's a good round out to 400m, which is exactly what the inventors intended. It's the #1 alternative caliber, and will probably stay that way and grow even more over the next five years, precisely because it amplifies all the good stuff about the AR.
You can find ammo, it's not horribly expensive, and you can likely afford a box or two for hunting every year. Even cheaper if you reload, which is what real shooters do when dedicated to it, like shotgunners or .45ACP.
Just don't fall into the naive trap of thinking it's the same as surplus. Not yet, if ever.
madcratebuilder
Member
Another area you may need to address is the gas and buffer system. An adjustable gas block or gas tube to control pressures at the BCG. A rifle length buffer tube, spring and buffer. Possibly a heavier buffer to control bolt speed.
Emphasis on may. I run an 18" 6.8 and a 16" 5.56 on the same lower (both mid-length gas). I am using the same buffer between the 2 with no over/under gas issues.
Other than the bolt itself, the BCG is the same (carrier, FP, cam pin, FP retaining pin). Since it is usually a good idea to have a bolt mated to its respective barrel anyway, I don't consider this an issue.
The 6.8 builders are using the same lowers and types of buffers, so they regulate the action by spec'ing an appropriate port size to deliver enough gas. That should give good action from carbine to rifle in buffers.
In 6.8 the majority of barrels are 16", which runs midlength gas. That's the optimum combination. 6.8 was designed from the case up to run the 14.5 and 16" barrel, not longer.
In 6.8 the majority of barrels are 16", which runs midlength gas. That's the optimum combination. 6.8 was designed from the case up to run the 14.5 and 16" barrel, not longer.
Cal-gun Fan
Member
I didn't mean that its not less expensive than other calibers, but unless you are going to be doing some bigger hunting, its expensive to plink with.
FlynnCastle
Member
Wow thanks everyone for the info. I know the 6.8 is more expensive I'm just looking for a little more power out of the old AR. I'll probably just end up getting a whole new upper so I can swap out quickly. As for reloading, well, maybe Fat Red Jesus will help me out with that next year....
You will definitely want to reload. All factory ammo is made for the older SAAMI spec'd chamber. While still enough to do what the cartridge was designed for, you really won't see it's potential until you roll your own and can get more velocity and great accuracy. The only exception is SSA's "tactical loads" that push a little faster than the norm and are only recommended for the improved SPCII chamber.
In case you are worried about the old v/s new chambers, the improved chamber is the norm with only a few manufacturers still clinging to it.
In case you are worried about the old v/s new chambers, the improved chamber is the norm with only a few manufacturers still clinging to it.
wally
Member
Ruger is now selling their 6.8 SPC SR-556 piston uppers separately now, so you have yet another option, although I've heard these are SPC not SPC II, I'm not sure of the difference or its actual significance, since I don't hunt and the $0.80-1.00/round ammo costs just isn't my kind of fun.
SPC II is the improved chamber that allows ammo to be loaded safely to levels that would cause excessive pressures in the standard SAAMI chamber. It is not a dramatic difference and is most easily compared to .223 v/s 5.56. If I remember correctly, Ruger, LMT, and Model 1 Sales are the only 6.8 manufacturers currently using the old chamber.
Shawn Dodson
Member
- Joined
- Dec 28, 2002
- Messages
- 3,198
I'm not so sure about that.
Some newer Hornady Custom 110gr BTHP/WC (#8146) ammo wouldn't always chamber in a 20" SPC barrel I purchased from DPMS in 2006. I contacted DPMS several months ago and discovered that I'd purchased an older SPC barrel. DPMS kindly rebarreled my upper with a newer SPC-II barrel at no cost to me, and the problem with Hornady factory ammo has not recurred since.
Unfortunately, most ammo is SAMMI spec unless listed on the box to be tactical grade and requiring the SPCII chamber with one in ten or slower twist. I don't blame Ruger for using the old SAMMI spec since most of their customers will shoot that.
While the history of the 6.8 is loaded with military intent, the actual reality is that hunting is it's #1 application for now. It delivers. That means the commercial ammo market is the baseline price, not 15 year old demilitarized surplus from a forward based ammo cache. Commercial hunting pricing applies. Anyone choosing to shoot lots of 6.8 rather than cheap military surplus should be knowledgeable enough to understand that.
It's constant theme in 6.8 threads to mention ammo pricing, what it really shows is some don't connect the dots: If it's not military surplus, it's not 25c a round. 6.5Grendel shooters complain about ammo costs, too, but they seem to be aware of it from the beginning. The .300 BLK promises cheap ammo, but nobody on their end is saying it will be .25c a round, not hardly.
Do shooter's deliberately pick a alternate wildcat caliber thinking it will be priced as cheap as milsurp or import? Are we saying the shooter is too stupid to understand, or is the comment really meant as a talking point on someone's bashing agenda?
While the history of the 6.8 is loaded with military intent, the actual reality is that hunting is it's #1 application for now. It delivers. That means the commercial ammo market is the baseline price, not 15 year old demilitarized surplus from a forward based ammo cache. Commercial hunting pricing applies. Anyone choosing to shoot lots of 6.8 rather than cheap military surplus should be knowledgeable enough to understand that.
It's constant theme in 6.8 threads to mention ammo pricing, what it really shows is some don't connect the dots: If it's not military surplus, it's not 25c a round. 6.5Grendel shooters complain about ammo costs, too, but they seem to be aware of it from the beginning. The .300 BLK promises cheap ammo, but nobody on their end is saying it will be .25c a round, not hardly.
Do shooter's deliberately pick a alternate wildcat caliber thinking it will be priced as cheap as milsurp or import? Are we saying the shooter is too stupid to understand, or is the comment really meant as a talking point on someone's bashing agenda?
I can't speak to that specific instance, but I am glad DPMS took care of your issue. I have heard of one of the Hornady OTM bullets causing some issues when loaded (handloaded) long. Not sure if that is the same bullet #, but SAAMI OALs are usually much shorter than people are loading. All bets are off if the chamber is cut on the smaller end of the tolerance and a cartridge is made on the larger.
I was just trying to clarify that 6.8 SPC ammunition is made to the same dimensions regardless of chamber. It is the powder charge that defines whether it should not be fired in the old chamber or not.
- Status
