Hello All!
First time poster.
I’ve been researching and have doubts so I’m reaching out for clarity.
My goal is to purchase the PSA AR15 11.5" pistol with SBA4 to use with multiple uppers. I’d like to buy a complete 5.56 then insert the CMMG .22LR conversion then, finally swap out a complete 9mm upper and use Endomags. This would be 3 calibers/ one lower. (3 guns in 1 sorta thing)
Is this even possible?
I’m also confused about the 9mm… does it need a change in buffers?
Thanks in advance for comments.
Marvin
Yes you can do that. I recommend you also figure out a way to mark/colorize your uppers and mags so you dont mix anything up.
I would not recommend trying a 9mm with this fashion because you will need a magblock insert, and a new recoil buffer and spring.
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no magblock needed with the EndoMag, you will need a 9mm buffer and spring
also with the Endo setup, remember will not eject with the mag removed as the ejector is part of the magazine conversion
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beware though i tired this for a bit and ended up with 3 different guns LOL
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Ah…i didnt see endomag. Yeah, no mag block needed but you will need buffer and spring.
figured dat
Rather than going with a 9mm upper, I picked up the AR-V in 9mm. I love that AR-V, although I might dump it some day for a JAKL in 9mm 
As for the .22LR, a dedicated upper is worth considering because of a 1/16 twist rate. The twist rate of an AR15 barrel isn’t optimal for .22LR at 1/7 or 1/8.
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Correct, it is not Optimal. However, the CMMG Kit is more than adequate for “cheap practice”.
Don’t forget to clean the rifle after shooting the rimfire ammunition - at the very least shoot 10-15 rounds of .223/5.56 through it afterward.
.22lr is quite dirty, leads-up the barrel some, and the chamber-adapter leaks gas a bit around the edges, fouling the chamber some.
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I’m watching quite a few videos right now of people doing the same thing I’m describing and no one has swapped out the buffers. They describe the BCG has added weight for assisting the blow back operation.
Yes, the bcg is heavier. 9mm uses extended buffers or buffer spacers and are often 5+ oz, way more than a 5.56 buffer.
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my 2 cents.
i went through all the building and finicky fixin. just buy the dedicated 22 upper.
buy a complete 9mm upper and the endomags.
and your 556 upper.
i am going to say you might switch around and get one right weight buffer to work but thats not much to switch.
i bought a transferable. technically it is an AR-15 select fire model 614. (fullauto)
basically an M-16.
after i removed the lower and parts i dressed it with a MOE stock and heavy buffer.
now i can swap to:
original 20 inch 556 barrel
a 16in of a couple of designs
mostly a 10.5 and 11.5 crome lined
an 8.5 SS 300 blackout upper with or without YHM suppressor
a 10.5 9mm
a 16 inch 762x39 upper
my dedicated 16 inch 22 from PSA
and a 6 inch 22 that usually has the Sparrow suppressor on it.
(not really) i call her Barbie and she dresses up real purty.
i need a new truck to be getting to the range.