Ummm, your bayonet would be a bit stubby on a carbine gas system...
Yes, but that is why it is there....really.
Stubby? Yes, but the hoards in Haiti were sufficiently intimidated by "stubby" a time or two.
And Colt M4's routinely break/crack bolts...really. This ain't hearsay. This was extremely rare with the old 20in rifles but fairly common today.
M4's are also famous for the dreaded "bolt over base" malfunction that will ruin your day. I believe the high port pressure causes this.
