Difference between a M4 Carbine and M16

[TAB56]

I have a question maybe somebody can answer, what is the difference between a M16 and a M4 Carbine?

 

[MaterDei]

Primarily barrel length. 14.5 vs. 20 inches. The M4 also comes standard with a collapsible stock.

 

[gun addict]

the standard M16a2-a4 variations has 20 inch barrels as opposed to 14.5 for M4 carbines. Also M4 has the M4 cut-feed ramp, along with the grenade launcher cut on the barrel. Typically M4 comes comes with collapsible stock while the M16 uses the full stock

there are other minor differences

 

[jobu07]

Comparing apples to apples with base models, off the top of my head 5 items: barrel, gas tube, rear sight drum, feed ramps, and buffer/stock.

 

[TexasRifleman]

Barrel length, twist rate (sometimes), feed ramps, buffer spring and tube. A few other details.
.

 

[jakk280rem]

i believe the m4 introduced the extended feed ramps too...?

 

[Jorg Nysgerrig]

Depends on which version of each you are talking about:
http://en.wikipedia.org/wiki/AR-15_variants

 

[d2wing]

The most critical difference is the length of the gas action. The carbine has the gas block much closer to the action and of course a shorter gas tube, resulting in a faster and more forceful bolt unlock and extraction. This in turn requires stronger extractor and spring, slightly heavier buffer and a shorter stronger recoil spring due to shorter buffer tube. The parts may lot much alike and fit together but mix them and you will have problems.

 

[Welding Rod]

How about the a fixed carry handle v. a flat top upper reciever.

 

[HorseSoldier]

How about the a fixed carry handle v. a flat top upper reciever.

Not a difference. Some M4 production had fixed carrying handles, later production went to removable. Pre-M16A4 M16s had fixed carrying handles, A4 does not.

 

[Tirod]

The carbine tube, buffer, and spring set are that - a complete assembly. Individual parts are not interchangeable with rifle parts.

The issue is that carbine gas and buffers tend to have bolt bounce issues on some guns. Doesn't seem to affect functioning much, but there is a difference in running a setup for a 14.5" barrel on a 16". It's not the optimum - and lots of carbine owners will jump in and mention they have no issues.

What has happened is the invention of midlength gas to correct it, and now, a small trend to retrofit rifle tubes, buffers, and springs to slow the action down even more. It gives the magazine time to feed the round into the feed lips. One spring pushing up 27 other rounds has to overcome the inertia of the stack first. Carbines are known for bolt over bullet malfunctions, this is an answer for that.

The M4A2 no longer has the M203 barrel clamp cut, which has always been a compromise. It's a classic example of the public buying something because it's milspec without understanding it might be wrong for what they need.

 

[FLAvalanche]

Nobody pointed out the big difference...

M16A2 is semi and 3rd burst. M4 has the happy switch.

Or where we just talking civillian models?

 

[Tim the student]

M4 has the happy switch.

No M4 I was ever issued had that. They were always 3rd burst too. I believe the fully auto is the M4A1, but I may be mistaken on that.

 

[RockyMtnTactical]

Yup, M4A1 is full auto and has a heavier barrel profile.

Here is a picture of the M4 and M16A2.