Question on AR pistol

Bowdog · February 4, 2023, 07:34 AM

If I remove a 10.5 " upper on an AR pistol and replace with a 16" upper will the firearm still function without replacing buffer and spring?

Screwball · February 4, 2023, 08:07 AM

It should… but can’t guarantee anything, since I don’t know what the setup on the pistol is.

If the 10.5” is overgassed to the point of an H3, and the 16” is undergassed, could be issues. Hard to say.

Other issue could be if it’s a blowback 9mm 10.5” and a 5.56mm 16”, the 9mm buffer setup is longer because of the shorter blowback bolt that doesn’t lock into a barrel extension. In that case, the 5.56mm bolt wouldn’t be able to go far enough back to cycle.

Shadow9mm · February 4, 2023, 09:16 AM

It depends on the 16in upper and the buffer in the lower. In general it should work. Worst case scenario might be a change in buffer weight.

Bowdog · February 4, 2023, 11:57 AM

Thank You, I believe it would work.

veprdude · February 13, 2023, 11:09 PM

Who's the 10.5" upper from?

One of the nice advantages of running a 10.5" upper is that about the only thing that changes from a 16" carbine is the barrel length. Most are just 16" barrels chopped to size (unless you have something fancy).

I have a PSA 10.5 and it runs fine on a run-of-the-mill buffer spring/weight.

February 4, 2023, 07:34 AM	#1
Bowdog Senior Member Join Date: March 16, 2010 Location: East Tennessee Posts: 112	Question on AR pistol If I remove a 10.5 " upper on an AR pistol and replace with a 16" upper will the firearm still function without replacing buffer and spring?

February 4, 2023, 08:07 AM	#2
Screwball Senior Member Join Date: May 16, 2012 Location: ME Posts: 747	Question on AR pistol It should… but can’t guarantee anything, since I don’t know what the setup on the pistol is. If the 10.5” is overgassed to the point of an H3, and the 16” is undergassed, could be issues. Hard to say. Other issue could be if it’s a blowback 9mm 10.5” and a 5.56mm 16”, the 9mm buffer setup is longer because of the shorter blowback bolt that doesn’t lock into a barrel extension. In that case, the 5.56mm bolt wouldn’t be able to go far enough back to cycle. Last edited by Screwball; February 4, 2023 at 10:20 AM.

February 4, 2023, 09:16 AM	#3
Shadow9mm Senior Member Join Date: March 21, 2012 Location: Indianapolis, IN Posts: 3,612	It depends on the 16in upper and the buffer in the lower. In general it should work. Worst case scenario might be a change in buffer weight. __________________ I don't believe in "range fodder" that is why I reload.

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February 4, 2023, 11:57 AM	#4
Bowdog Senior Member Join Date: March 16, 2010 Location: East Tennessee Posts: 112	Thank You, I believe it would work.

February 13, 2023, 11:09 PM	#5
veprdude Senior Member Join Date: March 18, 2019 Location: Texas Posts: 351	Who's the 10.5" upper from? One of the nice advantages of running a 10.5" upper is that about the only thing that changes from a 16" carbine is the barrel length. Most are just 16" barrels chopped to size (unless you have something fancy). I have a PSA 10.5 and it runs fine on a run-of-the-mill buffer spring/weight.