Bushmaster 5.56 M4 - Need to rebuild forearm

[Defiant1]

Gents...The forearm on my Bushmaster M4 5.56 is antiquated and I need to rebuild. This will be my all around defense weapon so while I need to be able to "reach out and touch someone" (300meters), I am setting the weapon up mostly for <50 meters with strong CQC competency. I want Military Grade/Ultra Durability and not afraid to pay for it. My optic is an EOTECH dot site with 3x magnifier and I need help with the following:

1. THRESHOLD QUESTION: I want to stay with my 14" barrel length with the welded 2" flash suppressor so it is not Class III. Here is the question: Can I buy a 14" barrel (mail order) without going through Class III processing and then have my gunsmith attach the flash suppressor as required for a non-Class III spec?

2. Suppressor: Surefire SOCOM762-RC, I will be using this 7.62 suppressor interchangeably with my 5.56. What muzzle break do you recommend with this suppressor?

3. Barrels: I am thinking 1:9 twist, chromolly lined, fully floating in 14". What are your recommendation for barrel brand, metal & twist?

4. Forearm grip: I want 4 sided picatinny and fully floating...what do you recommend?

5. Gas System: Recommendations?


This is my anarchy "go to" weapon, so money is not an object! Your help will be appreciated. Thanks!!!

 

[hewlett260]

First question, is this a serious post. Assuming yes, BCM barrel, 7" twist mid-length gas system, compensator of your choice, low profile gas block, troy, Samson or any other rail of your choice. Yes you can order just the barrel, assuming you intend to mount a Surefire suppressor, probably need their break and should probably look up NFA regulations so you know what you can and can't do legally.

 

[Defiant1]

Very serious! Thoughts on 1:7 verses 1:9 twist for 62gr 5.56 NATO rounds.

 

[J Max]

The mk12 douglas barrels carry a 1:7 twist rate, I say that only because I think the mk12 mod 0 or 1 or H should be the benchmark for accuracy when it comes to AR's. These barrels though are set to maximize accuracy with 77 gr ammo.

 

[Cobracutter]

1:9 is perectly find for just about any ammo you will find on the shelf. 77GR OTM and larger (well longer) bullets may have issues, but you are most likely not shooting that anway, and most of them have to be single hand loaded. 52-75gr should be fine.

How often do you shoot? How many rounds down the barrel?

Reason I ask is, it may be more cost effective to buy a new upper. You can get a quality BCM ELW with the new rail system and a bolt for around $1000. Add some BUIS and your good to go.

Or you could dremell off the FSB and delta ring and just install a new rail. I would cut the fbs down and grind it clean like a low pro gas block. Then you can add something like the FORTIS FF rail. You will need some tools, some understanding of how to build these guns, and the right fixtures and torque wrenches.

Your gas system is already set. Your barrel is drilled for a carbine system, so unless you want a new barrel, that is what you are stuck with.

I recommend you buy a whole new complete upper and keep the Bushy as backup and/or buy another lower so you have a backup gun. Its the path of least resitance and you can get upgraded everything at once.