First, yes I have access to a professional mill.

I need to know a few things. How deep? The barrel is a "heavy barrel" so it's mostly 1.00" and then .92" after the gas block. (AR10).  I'm thinking that .125" will be good.  Don't want to go any deeper, and any more shallow and I don't think it will be worth it.  

How many passes?  It's a Stainless steel barrel so machinability will be an issue and I don't want to work harden it with too many passes.  Also don't want to warp it.


Cryo treat?  Before/after/both?  Definately want to cryo treat it afterwards to take any stress out from the machining.  How about before?  I've heard that will help with machining it.

What kind of weight savings can I expect?  If I do in front and behind the gas block? (it's an 18" barrel)

$20 says I know what picture will show up soon.....

I can't believe I'm the first... must be a slow day.

That one will never get old!

You guys even read his post? He has a mill to do the fluting on.



OP - contact ADCO and see what they recommend.

My fluted HBAR 5.56 barrel (Bushmaster) appears to be .125" deep.  It also appears that the flutes were cut with a .250" ball mill.  As for the number of passes...  I don't know, not a machinist.

This is a bad idea. Put what ever you are drinking down and have a pro do the job I don't care if you have access to the tools if you don't have the training things might look good until

i say go for it , dont never give up on learning , go small at first 3/16 or a 1/4 end mill
after your first couple of passes you will start to see how it going to come out , have it mounted sturdy
in the vise and even use more lock downs if needed , i think you will be fine
show pics after wards of your barrel even if you booger it up alittle atleast you
tried it at the worst your flute may walk alittle .

TS2

I don't work with much stainless, but I would recomend using a carbide ballnose endmill. I would think the HSS endmills would wear out pretty quick. I'm guessing you are using an indexing chuck to hold the barrel? Probably a good idea to use a center in the other end of the barrel or you're going to have chatter problems. I'd make sure you have it indicated in on the diameter within .001" and check it in several places down the length to make sure it's straight. Take light cuts at first (.015"-.020") to get a feel for how it's cutting. Just take your time and make sure you have it set up perfectly, it's easy to make something look like shit if you don't do it right.

Correct, because no one here has the skills to do machine work on their own right?

That's my two biggest concerns.....making sure I can indicate it so it's perfectly level (or as level as I'll get it) and then making sure there is no chatter.  I've never machined stainless before....only aluminum-handguards and such.  Also, I've done passes in both directions with the aluminum (which is very easy to machine).....even done passes in both directions on my Glock Frame (cutting front serrations).......Do you think it would be bad to cut both ways on the flutes?....would it induce stress into the barrel worse than cutting in the same direction for every pass?  I would like to keep it to two passes if possible.

I think I may go ask over in the ADCO forum....perhaps he'll be willing to lend some insight

I would buy some ss bar stock first and practice, doesn’t have to be but a foot or so to get the general idea of how it’s going to work and turn out. Much cheaper than screwing up your barrel.

If you are doing this on a manual Bridgeport type machine DO NOT climb cut on any cut, regardless of material. You run the risk of the tool grabbing and it taking a chunk out of your part. This is especially true on an old worn out manual mill. Now if you are using a CNC mill you should be ok going back and forth, CNC's actually cut better when climb cutting. Just make sure you plunge at a low feed rate. I think you may end up having problems with the barrel warping no matter how you do it, when you machine long parts it does wierd stuff sometimes. Not sure what effect that will have on it shoots.

Good idea on practicing on a scrap bar first, it's a lot cheaper.

Cutting both directions on a manual mill is generally a bad idea, as all have some slop and the tool will grab when climb cutting. You can get away with it if you take light passes and snug the table locks a little.

If it were me, I'd make a set of brass center "inserts" that would fit over the tailstock and rotary table centers, to avoid damaging the muzzle/chamber(or bbl extension). Set up the rotary table and indicate the face to zero total indicator reading in line with the Y axis. Install the center and check it for runout with the indicator. Now align the tailstock as best you can and clamp it to the table. Install the bbl between the centers and then find the X center at one end. Move to the other end and see if it matches up. If it doesn't, move the tailstock a little at a time until it does...but make sure the tailstock is not cocked to one side or the other. After you get things lined up, put a couple of jackscrews under the bbl to keep it from flexing while you cut. I'd run about 1000-1500 rpm with just enough feed to keep it throwing a good chip(3/16 or 1/4 carbide ballnose) and keep it well coated with oil or coolant. About .020" depth per pass should keep it from chattering.

I would not advise trying to do this in a vise, because accurate placement of the flutes at xx degree intervals will not be possible(although a fixture could be made to avoid that)...and you'll also run the risk of collapsing the barrel a bit. If the flutes aren't accurately located in relation to each other, the stresses won't be either.

Screw fluting...turn it down to A2 Specs.  

Honestly, if you aren't 100% sure on this, you would be better off just selling your current barrel and buying a factory fluted barrel (light), an A2 barrel (lighter) or even a pencil barrel (lightest). Way less hassle, and the incremental cost would be modest.

Anyone have a link this original thread?  I miss it terribly.  Good times....

Study up. think it through. Make a few practice runs on lengths bar stock to get the hang of it. Take a deep breath and make it happen.

Nothing ventured,nothing gained.

This isn't about cost or anything like that.  This is about learning a skill.  THe reason I put a beaver tail extension on my glock was not that I needed it but that I wanted to learn how to do it.  I consider my "smith skills" to be at least moderate with certain modern firearms. I've done a pretty good job on my glock (trigger polish, throat/feed ramp polish, front serrations, beaver tail, stipple grip, refinish, etc). I didn't do alot of those things to "save money" or other reasons.  Did it simply to learn.

So, in that spirit...I want to learn to do fluting.......now just may not be the time.

You won't learn anywhere as much working on functional guns as you will on broken ones. You'll learn even more if you fix it till it's broke though.