Other answers are correct, additionally though, bayonets should work on almost any 20" barrels with rifle-length gas systems (such as the one you're looking at), 16" barrels with mid-length gas systems, and 14.5" barrels with carbine length gas systems unless any of them have non-standard muzzle devices that don't allow it to fit. The usual issue is on 16" barrels that have a carbine length gas system making the flash hider too far forward for the bayonet cross guard to sit on it properly but that isn't the case with this gun. Thank you for your service!

Yes it will fit these reproduction gins just fine

Ken, yes Sir. These reproductions are exact replicas and the bayonet will fit perfectly. No slop or wiggling.

Ken I think you're in business. These are pretty faithful reproductions. You bring back memories Ken. Haven't 'affixed bayonets' in a LONG time! :-)