Other than Barrel length and buttstock, are there any other differences?
Thanks,
AIRBORNE

Barrel lengths and the stock types are two points.  The early M4s had the fixed carryhandle (like the M16A2) later versions are flattop.  M4s can come in burst or full-auto M16A2s are burst only (M16A3 rifles are full-auto with the fixed A2 style carryhandle).

Oh Yeah the M4 has the deeper/longer feed ramps cut into the upper receiver.  M4s used to be the only ones with the extra strength black insert (for the extractor), now it is used as a replacement part for all rifles.

Quoted: Oh Yeah the M4 has the deeper/longer feed ramps cut into the upper receiver.

Does my new Bushmaster M4 Carbine have the deeper/longer feed ramps?

Do these deeper/longer feed ramps reduce the likelyhood of FTF ?

If I remeber correctly only the Colts can have the newer style feed ramps and hand guards.

I remember seeing something somewhere on this board wherein some branch of the service, probably the Army, was passing around Colt's technical date package on the M4 like it was a bag of peanuts and Colt was all pissy about it.

Anyway, stock, barrel, buffer, flattop, feed ramp cuts.  I think that's all the differences.

The M4 feed ramps are a patented Colt's feature -- amazing the simple stuff one can patent.  They aid feeding when firing AUTO from shorter barrelled rifles which cycle slightly different than 20".

I've mounted genuine Colt's M4 barrels in standard receivers (Colt's and others) and used standard barrels with a genuine Colt's M4 receiver.  No issues either way.

My "M16A2" currently uses a Colt's M4 receiver (early handled version) and a Bushmaster 20" government profile barrel.  The feed ramps don't match.  The rifle has never had a stoppage.

-- Chuck