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Converting the M4 Carbine/AR15 to shoot 6.8SPC?

Kroze

Diamond Member
Just wondering since I'm looking to build an AR rifle in the future, I don't want to waste money building a rifle and the US/NATO ditches the 5.56mm.

My question is, is it really that simple to convert your existing Carbine/AR15 shooting 5.56mm to 6.8SPC? I heard it's just a matter of replacing the upper receiver & bolt. No modification necessary on the lower receiver/buffer?
 
I don't see the 5.56 being replaced. 6.8SPC would be too expensive replacement, plus changing a NATO standard would be too complicated to implement. The last change was 50 years ago and the 5.56 is a great round.
 
5.56 isn't going anywhere though there's a lot of discussion about trying to change due to the poor performance in Afghanistan. Considering the shitty gas system we still use on the M-16 variants, I don't foresee this ammunition change to ever happen.
 
Just get a semi auto .308 and be done with it.

I have an AR-15 in 5.56 and a HK91 in .308. I personally wouldn't bother with new, specialty, or wildcat cartridges. Especially so if this your first semi auto rifle. If this is your first AR, stick with 5.56.
 
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even if the military changed, look at how many 5.56/.223 rifles are already out there owned by civilians. yeah, the round ain't going anywhere.
 
Just get a semi auto .308 and be done with it.

I have an AR-15 in 5.56 and a HK91 in .308. I personally wouldn't bother with new, specialty, or wildcat cartridges. Especially so if this your first semi auto rifle. If this is your first AR, stick with 5.56.
It's going to be my first personal AR. I have plenty of experience with the weapon through the military (Marines)
 
5.56 isn't going anywhere though there's a lot of discussion about trying to change due to the poor performance in Afghanistan. Considering the shitty gas system we still use on the M-16 variants, I don't foresee this ammunition change to ever happen.

I'm kinda surprised that the US never looked towards the Israeli arms manufacturing, they do have a lot of experience with the climate and conditions.

I'd love a Tavor but for now it's a G3.
 
In case of a nuclear fallout or a zombie apocalypse and you have somehow survived, your chance of finding 5.56 mm ammo in the wasteland is much better.
 
I can't answer your question, but I do agree with the other folks that it's a non-issue. The sheer # of 5.56 rifles out there, plus all of the ammo production to date, basically guarantees your supply for probably the rest of your life.

Think of it this way - do you know anyone having any trouble finding 7.62x54R for their Mosin-Nagant? Mass production of anything that chambered that round ended decades ago. (I realize it's still in miltary use today, but far from standard issue.)

Hell, I can still get GP-11 (7.5 Swiss) for my K-31. That thing was phased out in the 50's IIRC and the Swiss never actually fought a war with it.
 
Never even heard of 6.8spc until now. Good luck finding ammo for it, a quick search online reveals few sources and it's not exactly cheap nor widely available. 556 sure as hell isn't going anywhere especially with the adoption rate of rifles using it at the moment. Whether the military uses it or not will not affect civilian access to it. Besides, seems easy enough to buy a 6.8spc kit for it if you want to in the future. I certainly wouldn't buy a 6.8 rifle at the moment as they seem to be expensive and I'd rather have a gun with a wider availability of ammo (apart from a specialty of course).
 
If anything, if the military discontinues use, you'll see ammo get cheap for a while. What's the Army going to do with all of that 5.56 if they remove those firearms from service? The surplus market would be huge. Would probably see some awesome deals on it.
 
I think I'd wait for them to change first. What if you buy and they never change? Or they change to something besides the 6.8?
 
Just wondering since I'm looking to build an AR rifle in the future, I don't want to waste money building a rifle and the US/NATO ditches the 5.56mm.

My question is, is it really that simple to convert your existing Carbine/AR15 shooting 5.56mm to 6.8SPC? I heard it's just a matter of replacing the upper receiver & bolt. No modification necessary on the lower receiver/buffer?

To convert from 5.56 to 6.8, all you need to change is the barrel, bolt and magazine. So, basically, buy a 6.8 upper and some mags, and you can switch back and forth very easily.

But I agree with the others, 5.56 isn't going anywhere any time soon.
 
To convert from 5.56 to 6.8, all you need to change is the barrel, bolt and magazine. So, basically, buy a 6.8 upper and some mags, and you can switch back and forth very easily.

But I agree with the others, 5.56 isn't going anywhere any time soon.

This.

Simple.
 
5.56 isn't going anywhere though there's a lot of discussion about trying to change due to the poor performance in Afghanistan. Considering the shitty gas system we still use on the M-16 variants, I don't foresee this ammunition change to ever happen.

There isn't a damn thing wrong with the DI gas system, people just don't take the time to learn how to keep them running correctly. As long as you keep it lubed they will run dirty as hell.
 
Clearly a gas driven system is at a disadvantage to a piston driven system though but boomhower is correct; keep it (relatively) free of carbon build-up and lubed, it will run forever. Keep a spare bolt of extractor in your pocket just in case 🙂
 
The fact that you have to 'learn' how to keep a AR-15 functioning compared to a piston system weapon just proves the flaw in the DI system.

That said I love my AR-15. It is however the most picky rifle I've ever owned. It's picky on ammo, picky on cleaning, and picky on lube.

By contrast, my $300 WASR will fire anything, using anything mildly lubricating as lube, and probably would be fine if I cleaned it with a garden hose and spit.
 
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