That's certainly possible. But I'm not the one.
I am certain that bayonets that fit M16’s, M16A1’s and M16A2’s do not fit M4’s.
Well, THERE's your problem!
You seem to be writing that the new OKC-38 bayonet fits both M16’s and M4’s. The distance between the flash supressor and bayonet lug is quite different between M16’s and M4’s.
It's not all that different. But the important part is that the bayonet's ring is free to slide over the entire length of the flash suppressor. And any of the M16 series of bayonets, from the Vietnam-era M7 issued with the M16A1 rifle to the Lan-Cay M9 and new OKC-38s- plus a couple of other designs- all latch onto the basic bayonet lug, whether on an M16, N16A1, M16A2 or M4. They won't fit on the old XM177E2 CAR15 because the muzzle device was larger than the 22mm diameter of the M18 flashhider, and because the bayonet lugs on most of those rifles were ground off. That was also the case with some M16 rifles fitted with the XM148 40mm grenade launcher, forerunner to today's M203...because during Tet '68, some overenthusiastic ARVN Marines fitted bayonets to their M16s and then tried to fire HE rounds from their bloopers, with unfortunate results. That was one of the considerations when the military JSSAP program was developing the M16A2 rifle, at that time, mostly to meet USMC requirements- which included the use of the bayonet. But I digress.
The point is, there's enough point and blade tip extending forward of the flash suppressor to get the job done. True enough, it isn't usually done with a bayonet these days, but the sharpie pointy thingie remains useful for a couple of reasons: riot control [don't hear much about that one nowadays, tho] moving prisoners around, and more to the point, letting those used to seeing armed personnel standing guard with usually-empty weapons that when the bayonets are on, the ship's Marine detachment is loaded for bear and means business. That can be the case for airfield guards, embassy personnel and those on the Nuclear Position Duty Roster as well.
But just to be sure, I checked. Click Yep, the old M7 locks up just fine on my old circa 1970 M18A1. Click! Yep, it locks up on my M4 [more precisely, a Canadian Diemaco C8A3] as well.
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