I’ve been tinkering with the idea of taking my M4gery and converting to from a conventional hand guard/front sight post to a free float tube and gas block. Most gas blocks I see on store shelves are Anderson arms and I’d be ok with that but I know nothing of them.

I’m not looking for stupid expensive just a basic gas block to accommodate a free float tube. If the Anderson arms are ok then I can just run to the store and get one. What’s up with the different diameter sizes though? Every one I’ve seen has a diameter measurement on it, will I need to put a micrometer to my barrel and measure its OD to match a GB?

1) Any steel gas block is likely to be fine, some are made of aluminum and those won't hold up.

2) Diameter is generally .625 for pencil barrels and .750 for everything else excepting atypical profiles like those found on varmint or precision uppers. A standard M4 profile barrel will take a .750 gas block.

3) If it is a standard pinned FSB you have two options. One is to remove the FSB and replace it with a low profile block. Option two is to cut the FSB down and make it into a low profile gas block. Option 2 is cool because it is free and it is already drilled for pins vs using a set screw.

Yup, what he said.  Cutting down the FSB seems the most popular route I've seen done for folks going for affordable.

That’s one route I thought about to was cutting the FSB. Hell I may even do that to

I love my superlative it's not cheap but it is nice to adjust where your cases land.

It's .750 for sure.
I've had quality (roll pin hole not in the right place ) problems with the uber cheap (less than $10) no name blocks.
Anderson should be GTG.
I (and it's just me) would never cut a existing FSB down.
While it's by far the most secure way you've effectively condemned that barrel to never having a triangle FSB ever again.
Which means no carry handle.
Which makes me sad.

So I actually did cut the FSB off, went pretty well. I got some of that PermaBlue stuff to cover the exposed metal after I round off the edges. Still looking for the free float my brother gave me but I may have to just buy a new one

Man gets freefloat handguard for AR but must have lower gas block to use it.

Dilemma.

 Man solicits advice from fellow gun nuts.

 Man hacks existing gas block down to size.

 Hmm...man can't find freefloat handguard that precipitated entire ordeal.

Dilemma.  

Man then solicits advice from fellow gun nuts on how to return hacked up gas block to original condition.

Man has completed the ArfCom circle of life.






Make sure you post a pic of it with the new handguard when you find it.  We're vested in it now lol.  If you have to buy another consider Midwest Industries. I've put MI handguards on my last two.  Extremely good products.  If I were going to buy another I'd go with a Midwest again.

Give Fortis rails a look, they use the standard barrel nut so you won't have to bust it loose. You can even dremel off the delta ring and yank the spring/snap ring with pliers.

https://www.primaryarms.com/fortis-rev-2-m-lok-handguard-14in

Fortis Rev II's are my favorite rail but they can be pricey.
The 12 inch KEYMOD is on sale about $50 or so cheaper than the 14" M-lock.

There's solid enough tubes around in the $50 range, just don't ask where they're made.