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EOD3
09-06-2008, 7:30 PM
What are the limitations when swapping uppers on an AR15?

technique
09-06-2008, 7:34 PM
None. As long as you maintain a 16in barrel.

aplinker
09-06-2008, 7:54 PM
That the new configuration be legal and match the lower.

This is an odd question.

Can you expand a bit and maybe we can address what you're thinking could be an issue?

technique
09-06-2008, 7:59 PM
I was thinking the same plinker.


OP you can put a bunch of uppers on your lower as long as they are compatible with the traditional 5.56 lower.

For example a .308 will not work due to the larger length of the upper.

But for example, 22,9mm,7.62x39,5.56,458s,50b,6.8, and even 50DTC will work with your standard lower.

EOD3
09-06-2008, 9:16 PM
What I'm looking for is information about limitations when swapping uppers on a 5.56 AR15. Clearly, the upper must physically fit onto the lower receiver. Are there any limitations pertaining to caliber and/or chamber pressure maximums or minimums. Some of the larger/slower calibers such as the 300 whisper or one of the short case 35's.

Obviously, I need to work on my communication skills or have my wife proof-read my posts.

Young Version
09-06-2008, 9:33 PM
What I'm looking for is information about limitations when swapping uppers on a 5.56 AR15. Clearly, the upper must physically fit onto the lower receiver. Are there any limitations pertaining to caliber and/or chamber pressure maximums or minimums. Some of the larger/slower calibers such as the 300 whisper or one of the short case 35's.

Obviously, I need to work on my communication skills or have my wife proof-read my posts.

Longer action calibers (22-250, .260, .308, .338 Federal, etc) require an AR10 platform. Shorter action calibers (.223, 6.8SPC, 7.62x39, pistol cartridges, .22LR, etc) work with a standard AR15 lower.

Other than length, the options are pretty much open. The lower isn't the stressed part and pressure isn't a concern.

ar15barrels
09-06-2008, 10:32 PM
What I'm looking for is information about limitations when swapping uppers on a 5.56 AR15. Clearly, the upper must physically fit onto the lower receiver. Are there any limitations pertaining to caliber and/or chamber pressure maximums or minimums. Some of the larger/slower calibers such as the 300 whisper or one of the short case 35's.

The limitations you will run into when widlcatting in the AR-15 are bolt thrust, magazine length and ability to feed
(cartridge case design and compatability to magazine).

Be more specific and I can give more specific advice.
300x221 (whisper) runs great.
It was actually designed to be used in the AR first before it got more popular in TC's.

aklon
09-07-2008, 12:49 AM
I have an Oly and it looks like the receiver is pretty soft as the charging handle latch sometimes doesn't hold. I was thinking of replacing it with another Olympic Arms upper, specifically the one on the K7 Eliminator. That's the one with the 16" barrel but with the longer sight radius of a 20" rifle. From what I've gathered here, this would be no problem.

aplinker
09-07-2008, 2:02 AM
What I'm looking for is information about limitations when swapping uppers on a 5.56 AR15. Clearly, the upper must physically fit onto the lower receiver. Are there any limitations pertaining to caliber and/or chamber pressure maximums or minimums. Some of the larger/slower calibers such as the 300 whisper or one of the short case 35's.

Obviously, I need to work on my communication skills or have my wife proof-read my posts.

It's ok... We like to help and I couldn't quite get what you wanted answered. Your rephrasing, once again, was spot on and gave us just what we needed.

There are a huge number of proven and well-used calibers on the AR platform. Many more are used in "bolt action" uppers, as well (not feeding from the magazine).

Randall is our resident expert, but off the top of my head... here are some commonly used calibers on AR15 that do feed from a magazine:

22lr (and all its lovely variants...)
9mm
40S&W
45ACP
5.56
7.62x39
6.8spc
6.5grendel
5.45x39
458SOCOM
450Bushmaster
50Beowulf

There are plenty more less common ones, as well. Last count I remember it was around 40.

CSACANNONEER
09-07-2008, 7:40 AM
I have several different uppers ranging from .22lr to a single shot, bolt action, 50BMG.

aplinker
09-07-2008, 10:38 AM
I have several different uppers ranging from .22lr to a single shot, bolt action, 50BMG.

What?! 50BMG?! You?! :p ;)

EOD3
09-07-2008, 10:51 AM
Thanks guys. I've been to Randall's website and checked out the 300/221 and the 30 HRT. Forming brass doesn't look too bad and both are based on rifle brass.

CSACANNONEER
09-07-2008, 10:53 AM
What?! 50BMG?! You?! :p ;)

Yea, but I've only got one. So far I haven't been able to figure out how to mount a 3" Parrot Rifle to a lower though. Maybe someday?