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Question about uppers and lowers

1369 Views 11 Replies 0 Participants Last post by  fal guy
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... and no this isn't about what you prefer in women :p ! This actually could be a dumb question ...

Can you take a .308 upper and mount it to a 5.56 lower? I'm not sure if there is a difference in .308 mag size which would affect the mag well size.

Thanks!
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no you cant do it. dont ask me why but ive asked the guy at my local gun shop because i was wanting to pick up a complete .308 upper and interchange on my lower and he said that i would have to get a lower made for a .308

i think your right is becuse the size of the round is bigger and requires a differnt size mag. but i could be wrong
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no you cant do it. dont ask me why but ive asked the guy at my local gun shop because i was wanting to pick up a complete .308 upper and interchange on my lower and he said that i would have to get a lower made for a .308

i think your right is becuse the size of the round is bigger and requires a differnt size mag. but i could be wrong
Bummer. I was thinking this might be the "easy and cheap" way into the .308 round.
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i actually think it has something to do with the hammer but im not sure
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The length of the round is different so it would not be able to accept mags made for .308. Single shot? maybe...
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get a 6.8 upper
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mag well size

and I'm guessing a buffer and buffer spring issue

among other things
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You can't because the specs are almost entirely different altogether between the two.

An AR15 lower and AR10 upper won't even mate up at the pins. Hence primarily because of the magwell is considerably longer in the AR10, though there are several more differences too, but not being able to join them together would be the main reason they won't interchange.

If you're wanting something along the ballistics of the .308 in an AR platform, consider the 6.5 Grendel upper.
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450 bushwhacker !
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You can't because the specs are almost entirely different altogether between the two.

An AR15 lower and AR10 upper won't even mate up at the pins. Hence primarily because of the magwell is considerably longer in the AR10, though there are several more differences too, but not being able to join them together would be the main reason they won't interchange.

If you're wanting something along the ballistics of the .308 in an AR platform, consider the 6.5 Grendel upper.
OK then ... will the 6.5 Grendel upper fit a 5.56 lower?
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OK then ... will the 6.5 Grendel upper fit a 5.56 lower?
Absolutely.

The only differences in them are the bolt, barrel chambering (obviously) and they use a dedicated magazine as the feed lips and followers are different than 5.56, but they will fit any spec AR lower with no modifications whatsoever.

Alexander Arms holds the copyright to them, but there are several other places making them.

At midwayusa, you can even buy the kit that includes all the necessary parts (bolt/barrel/mag) to change an existing upper for 6.5 grendel. And much less expensive to boot.
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even though you think I'm a sexist..

ar15 lowers won't work with a 308. however fulton armory(aka dpms) and
PoF make ar10 lowers. that will suit your 308 needs. fulton armory ones are less expensive, but you won't be able to fit chip mcormick or timney triggers in them. PoF is way expensive and I've had trouble using lower parts kits in them. they will use the same buffer tube's and lpk's with the exception of bolt catch , mag release and buffer spring. so good luck. uppers from dpms are made to fit the
platform, and are availible in 16" med con w fh's to 24" fluted bull's.

you can get a veriety of calibers to mount on the ar15 lower. 50 beowulf
7.62x39 22lr 6.8spc 6.5grendal and many others even 9mm and 40
check ar15.com those PEOPLE will be able to help you out.
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