dumb question i guess

[••SpraynPray••]

Is the AR15 and the M4 lower the same thing?

[jpavoncello]

A true M4 (military issue) is a full-auto weapon. The lowers are identical except the fact that one accepts a FA sear and the other doesn't.

[wjkuleck]

Is the AR15 and the M4 lower the same thing?

Well...it depends.

Strictly speaking, the AR-15 is generally semiautomatic-only. The true military M4 is a select-fire weapon.

In our civilian context, however, the AR-15 (A2 and later) and "M4" are exactly the same, lower-receiver-wise. The buttstocks vary, and you'll see different markings, perhaps, but that's it.

The real differences are in the upper receiver assemblies. Since AR-15/M4 upper receiver assemblies are interchangable (let's not get into some of the subtleties, thank you), you can have an "M4" upper receiver assembly on your AR-15, and vice versa.

Regards,

Walt

[39flathead]

A true Colt M4 lower would have additional markings for the selective fire options, but the internals of a normal AR15 will work.

[••SpraynPray••]

sweet thanks guys

[King 5.45]

A true Colt M4 lower would have additional markings for the selective fire options, but the internals of a normal AR15 will work.

Colts are specifically blocked in their internal construction against the introduction of select-fire guts, IIRC. Basically, what you're looking for (IOW, what you would see) in a select-fire sear is one that goes bouncy-bouncy, up and down, within the AR FCG.

Here's a full-auto conversion of an AK with an explanation of how that particular one works: http://www.youtube.com/watch?v=OMIIC_MIxMA I'm not sure where this guy is, but such monkeyworks without the appropriate manufacturing license would land you in Lewisburg for about ten years or so.