AR15 5.56 vs AR15 300BLK

[marten]

I have a STAG Arms AR15 in 5.56 and am considering purchasing a .300BLK upper. Would I have any difficulty switching out the parts, what would be involved, and once the switch is made, would there be any problem in switching back and forth as the need arises?

[SouthPaw]

The only part you need to switch is the barrel and ammo. BCG, mags, upper and lower are all the same. No problem
switching back and forth but eventually you will probably get tired and to build a dedicated 300 blackout rifle.

[SideShow Bob]

If the OP is going with a complete upper with BCG, it would be easy peasy to swap back and forth. Even if the .300 BLK required a different buffer and spring.

I did it often with a .458 SOCOM upper until The floods of 9/13 washed everything away.

[MarkCO]

Buying an upper is just pop the pins, change upper, pins back in. Very easy.

If you want to go cheap, the simplest would be to buy a barrel, upper receiver and barrel nut compatible with your hand guard. You could, in a minute or so swap over a BCG, CH and HG.

If you bought just a barrel, you will be re barreling for a caliber change.

The thing to watch is to make sure you check ammo to be compatible with the caliber upper you are using when you load magazines.