Colt has used so darn many model numbers, it takes an engineering degree to just keep track of everything. Per Colt's LE catalog, their non-military / LE version of the issue M4A1 is either the model R0777 or R0977. Both are very similar in all respects to the military issued M4A1's, complete with all the new M4 improvements. ( M4 = 3rd burst / M4A1 = full auto. ) The R0777 has a non-detachable handle, where the R0977's is detachable to allow more simplified mounting of various optics & night vision devices. I hope this has been of some assistance to you. Regards, Dom Pastore Jr.