416 Outer Barrel

[Abbot]

So I'm planning on buying an M4 and putting a 416 RIS and body onto it. My question is what barrel am I to use? I've tried researching, but found no answer. If the RIS is 10.5", I gather I should use a 11.5" barrel, correct? But does it have to be a 416 barrel, or will an M4 barrel do (and look like a 416)?

[TheEnd]

A 416 barrel is very different from an M4 barrel. It has a thicker profile and the piston system. The gas block is unique as is the barrel nut. The barrel nut is very important as it has a groove in it where the RIS retaining bolt passes through. You will also need the RIS retaining blocks that the bolt threads into.

You won't be able to convert an M4 to a 416 using just that receiver and RIS. For the upper you will need:

- 416 receiver (be sure it is the same brand as the RIS as many have proprietary profiles)
- 416 barrel (many are two piece for 10" and 14")
- proprietary gas block
- proprietary piston and spring
- 416 barrel nut
- RIS retaining blocks (one is threaded and the other is not)
- Specific 416 RIS bolt (has a giant Phillips-like head)

I believe that's it. You will be better off buying a boneyard donor rifle or just outright buying a 416.

[Abbot]

Good advice. Last time, I bought some 416 externals which came with the body, barrel, barrel nut, RIS, retaining blocks, and gas block. All I had to do was drop in my G&G gearbox, I mickey-moused an M4 charging handle into it, and put on the stock and pistol grip. But I guess I'll just have to hope for someone selling some externals.