Am new to the forum and to AR-15's.  Trying to figure out which one to get or to build.

My question for the moment concerns lenght.  I like the 16" size barrel/rifles, but what is the difference in the mid length and the CAR and the M4?  Which one is best in a 16" model?

thanks alot!

All civilian barrels that don't require NFA paperwork need to be 16" or longer.

civilian M4 = 16"  military M4 = 14.5"  You can permanently add a FH to the 14.5" M4 barrel to make it legal.  But since you need 16" anyway, it makes some sense to just get a 16" barrel in the first place.

Mid-length and CAR refer to the gas system.  M4 uses the same one as CAR.  On a mid-length the gas port is further away from the breech and that should make it run better.  The CAR port is closer to the breech and can errode more quickly, leading to less reliable function.

In the majority of cases, the mid-length 16" barrel offers the best compromise for civilians.  You can also get a more diverse selection of profiles (thickness) for a mid-length.  An M4 barrel has cut-outs that serve no purpose except looking cool since you probably won't mount an M203.

G

Several problems with the post above, but rather than correct his errors I suggest you do your own homework and make your own decisions about what model AR15 will most fit your intended use.

We have made it very easy for folks to get up to speed around here.

All that is required is to be able to read.

Uptop is an INFORMATION button which discusses the brith, history and current developments w/ the AR15/M16 firearms, read what interests you there.

Also Up top of almost every forum you'll find a plethra of TACKED threads, most of which contain some admonishment to READ THIS FIRST or BEFORE POSTING, do that!

If you take the time to do this then you will be able to point out to the guy above that:

1. you can cut almost a full inch OFF the total length of your M4 rifle by chosing the 14.5" w/ perm FS option (over the 16" M4)

2. While mid-length and CAR length gas systems are described accurately enough above his personal bias is showing with his unwarranted digs at the CAR system which is NOT less reliable as he stated

3. (again here his bias is wholly evident as he seeks to have you overlook what I consider the most versitile of AR choices and in which IF you pick the correct twist rate and feed it the correct fodder you will end up with a more compact rifle than him and one that'll be every bit as accurate out to 600 yards or so and possibly even more accurate at that range depending on where his twist bias lies....)

Once your done with your research you'll like myself and g23 above have your own biases, but your knowlege about your choices will be expanded by your own education, instead of the rantings of arm-chair commandos like us......

mike

eta - forgot to mention, Welcome aboard

thanks

Quoted: Am new to the forum and to AR-15's.  Trying to figure out which one to get or to build. My question for the moment concerns lenght.  I like the 16" size barrel/rifles, but what is the difference in the mid length and the CAR and the M4?  Which one is best in a 16" model?

Truly almost a matter of personal preference.

Points reflecting my opinion:

    1.  The M-4 barrel profile seems unnecessary since I don't intend to mount a grenade launcher or one of the fake clones/flare launchers.

    2.  Only the mid-length allows mounting a bayonet.  On the others, the front sight base is far enough aft that the ring on the bayonet will slip off the flash hider and be loose on the barrel.

    3.  I like the proportional look of the mid length better than either of the other choices.