After finding several new M4s at work with loose barrels I decided to film the process of tightening them back up. This is basically the whole process you would follow to remove and replace a whole barrel assembly.
Worth note – I reused the gas tube spring pin in this video as I don’t have more on hand and have to turn the weapon back over to the unit it belongs to right away. The unit is located a days travel from my shop, so tagging out the weapon and ordering a pin is not exactly feasible. That said, when you do any process like this, or any time you remove a roll pin/spring pin, or a cotter pin, you should replace it. Spring pins lose their spring action when removed, which is why I used that second punch to open it back up and make sure it doesn’t come loose.
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Isn’t there a tool you’re not using that supposed to go into the barrel to keep things from twisting
Good video and notes. Well done. I'd love to have that FN heavy barrel. I know you have a good feel with a barrel change, but the common man should use a torque wrench. Once again thanks.