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Discussion Starter · #1 ·
I have an AR-15 with a 16" barrel in a .223. I want to make a swappable upper with a 24" barrel in a .308. What do I need to do for this modification. Do I just need a regular upper and a .308 barrel or is there more to it than that?
 
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Discussion Starter · #3 ·
AFAIK you can't do it. You need a 308 lower like those from DPMS or others who make ARs in 308 Win. You can go to a pistol caliber or a similar rifle caliber like 204 Ruger from your 223 Rem, but not up to 308 Win.
 
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Discussion Starter · #4 ·
I have an AR-15 with a 16" barrel in a .223. I want to make a swappable upper with a 24" barrel in a .308. What do I need to do for this modification. Do I just need a regular upper and a .308 barrel or is there more to it than that?
You'd need upper, lower, barrel, and about half of the furniture and stuff and almost all of the internal parts in the guts of the system to go along with it.

Basically, you'd need a whole other gun because 308 is too long to fit in an AR15's magwell. The AR15 is the AR10's (308's) baby brother, and is essentially a scaled down version.

Bottom line, it won't work, but there are literally tons of other larger or even smaller calibers if you'd like just by swapping uppers or barrels, bolts and magazines, but 308 is out of the question in an AR15.
 
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Discussion Starter · #5 ·
So, is there somewhere I can get parts to build a complete AR in .308? You say it's an AR-10?

Also, what calibers could I use to keep all the parts the same as an AR-15 but be close to a .308 in terms of accuracy, distance, and power?
 
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Discussion Starter · #7 ·
So, is there somewhere I can get parts to build a complete AR in .308? You say it's an AR-10?

Also, what calibers could I use to keep all the parts the same as an AR-15 but be close to a .308 in terms of accuracy, distance, and power?
The AR-10 is the AR-15 in .308. DPMS calls their version the LR-308, but I don't know what interchanges between them.

Sounds to me like you're looking for the 6.5 Grendel. Do a google search or search here for it and you should find plenty to read up on.
 
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Discussion Starter · #8 ·
So, is there somewhere I can get parts to build a complete AR in .308? You say it's an AR-10?
Yeah, but its quite expensive. Probably cheaper to just buy a DPMS .308.

Also, what calibers could I use to keep all the parts the same as an AR-15 but be close to a .308 in terms of accuracy, distance, and power?
The best out there so far are the 6.8 SPC and 6.5 Grendel. Both will fit in the AR platform and only require a new barrel, bolt, and magazine.

I must say I know very little about the 6.5 Grendel other than that it came from the benchrest community and has a fantastic potential for accuracy, though slightly behind the 6.8 in terms of terminal ballistics. Here's some readin' for ya:
6.8 SPC FAQ
Ko-Tonics (makers of 6.8 SPC barrels/uppers, also one of the leading developers in loads for the 6.8)
Alexander Arms' 6.5 Grendel page
 
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Discussion Starter · #9 ·
The 6.8 SPC looks pretty good. Will it have the same effective range as a .308 though? Will there be much difference in accuracy between a 20" and 24" barrel with a 6.8 at say 1100 yards?
 
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Discussion Starter · #10 ·
The 6.8 SPC looks pretty good. Will it have the same effective range as a .308 though? Will there be much difference in accuracy between a 20" and 24" barrel with a 6.8 at say 1100 yards?
At 1100 yards? You might want to invest in a good .300 Win Mag...

Assuming you meant 100 yards, no, there will be no appreciable difference in accuracy. I dont see any reason to get a 24" 6.8 SPC.

As for the effective range, from what I've heard, the 6.8 should be kept under 500 yards when shooting at anything other than paper.
 
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Discussion Starter · #11 ·
I meant 1100 yards but it was hypothetical. There is a local 1000 meter range that I plan to use for long range shots. Right now I only have an old 30-06 to use at it but I want an AR (or something similar) to replace it while staying effective. I use my mid length AR on shorter ranges. I trust it at 100-300 yards.
 
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Discussion Starter · #13 ·
Although the 6.5 Grendel is capable of 1000+ yard shots, at that distance, I'd go with a good Remington 700 Police/sniper in 300 also. For a couple of reasons really. The biggest being weight and manueverability, the second biggest is downrange velocity in a closed bolt system will be much better than a semi action that uses some of the gasses to cycle the next round for you.

If you just have to have it in an AR platform, the DPMS would be my choice because the Knight's SR25 308 is just way outta my price league all at once for about the same thing minus the military contract numbers for around 1/3rd the price in the DPMS setup.

My 2 cents
 
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