Barrel profiling - your experience?

[119er]

I have a DPMS G2 Recon on its way and I would really like to have the barrel(stainless) re-profiled to shave some weight. This will be in addition to changing the HG for a 12" MI rail. I want the rifle as easy to carry(light) as reasonably possible and I would like it to maintain acceptable accuracy if it gets some heat in it too. Nothing crazy, but now and again I could see myself going through a couple mags ringing steel and having fun.

My plan: - Send the barrel off to Adco for their medium weight contour under the HG and possibly countour, dimple, or flute forward of the gas block.

My concern: - I end up with a barrel that wanders excessively when it gets heated. By excessive I mean opens up more than 2-3 MOA. I do understand that barrels are creatures of their own and there is no magical answer to this question. I would just like a general discussion with people who have been over this ground.

If anyone knows:
Are stainless barrels stress relieved at some point during manufacture?
Does the bead blast finish offer any benefit in that regard?

 

[Jackal]

Sounds like you shouldve gotten the AP4 model like mine. 6.8 lbs empty and shoots better than I do. About 2.5-3moa with gravel pit Tula/Wolf/reman ammo. Havnt tried any fancy stuff yet. Adjustable gas block negates any advantages of the mid length Recon. Mines going to be wearing a Griffin Recce 7 silencer REAL soon.

I looked at the Recon, but decided the lightweight 4150 chrome lined barrel is better for my purposes.

 

[M-Cameron]

If anyone knows:
Are stainless barrels stress relieved at some point during manufacture?
Does the bead blast finish offer any benefit in that regard?

Bead blasting is solely cosmetic, and has no bearing on the strength or any stress releaving of the barrel.

 

[rcmodel]

See post #2.

If it's not too late, cancel the order and start over again.

I'm not saying nothing ever good happens with turning a barrel down.

Sometimes it does, and sometimes it doesn't.

rc

 

[119er]

Sounds like you shouldve gotten the AP4 model like mine.

Slightly patronizing, but nice rifle Jackal, I've seen it in the threads here.

Bead blasting is solely cosmetic, and has no bearing on the strength or any stress releaving of the barrel.

I was confusing shot peening with bead blasting.

 

[AJumbo]

Dies anybody cryo anymore, or am I hopelessly mired in the last century AGAIN?

 

[Jackal]

Slightly patronizing, but nice rifle Jackal, I've seen it in the threads here.

Sorry, wasnt supposed to be. If you purchased it from a major online retailer like Bud's, simply deny transfer and they will send you a return label for return shipment. Simply swap it for the lightweight model. Since you are replacing the free float anyway and want a lighter barrel, the AP4 seems to make more sense.

 

[119er]

No problem, it is a really good alternative, and I was considering it based on your posts here, but I'm hung up on wanting a stainless barrel. Being that aftermarket barrels are slim to none, that leaves me with the recon. There is a thread somewhere else where someone has done this and I would like to do the same. I know I am paying a ~$200 premium to get what I want.

As for Cryo treatment, I haven't the slightest. I used to hear about it in my automotive hobby years back, but not much anymore.

I'm really just looking for a lightweight, corrosion resistant gun that is reasonably accurate, and looks kinda cool. (Subjective) I have a couple park'd AR's, just want that blasted stainless look for this one. Silly as it sounds, I am just getting my "cool" gun bought and finished up how I want it before elections roll around and potential madness ensues.

 

[rbernie]

I've never re-profiled a barrel, so I can't offer any real-world feedback on that. The only advice that I can offer is to resist the urge to make the barrel too thin. You will potentially find that the balance of the rifle becomes too butt-heavy for your needs or desires.

It may be best to just shoot it for a bit and see how it works before you commit to any changes.

 

[Jackal]

The G2's are one of the best rifle designs to come along in the last 10 years. Size/weight of an AR15, with a .308 payload. I do suggest shooting it a bunch before voiding your warranty though, as mine DID have to take a quick trip back to Minnesota for repair (tight chamber, light buffer spring, faulty bolt catch). The customer service I received was excellent.

 

[119er]

I do intend to shoot it as it comes from them first. I am just trying to get a consensus of results so I can weigh the of benefits profiling. The barrel and optic is my only question mark. I want to offset the weight of the optic and mount as much as possible.

For optic, I want a 1-4x or 1-6x with etched, illum. reticle. I'll be paying a 17-22 oz. penalty for it. The HG drops ~7oz. while the muzzle device (BCM) is probably a wash. Sling and mount will tack on another 8-9oz. Someday a silencer may be an option as well.

It's likely that I will have it profiled, if for nothing other than to see what actually happens. I am going to look into stainless barrel manufacturing to see if they are profiled and left as is when new.

 

[Jackal]

I wouldnt imagine the profile would affect things very much, as there are many stainless pencil barrels available for the AR15.

As for optics, the Aero Precision mount is for sure the way to go. My Leupold 2.5-8 VX3 and Aero mount weigh a combined 14.4oz. My whole rifle, with loaded 20rd mag and optics weighs right at 9lbs. Not bad, considering most iron sighted, stripped, empty battle rifles weigh the same or more.

The muzzle device on the AP4 is very effective, but its a boat anchor at 5oz.

 

[119er]

That is kind of what I am taking away from a casual look at it. Stress relieving after finish machining causes problems of its own, and stainless is wholly different than carbon steel.

I've read on various other forums that the removal of the extra material doesn't really add any significant stress but will possibly relieve or redistribute stresses already present. That could have a similar effect as adding stresses though.

Others say that button rifled barrels will tend to open up in dimension slightly where the material is removed.

That leaves normalizing or cryo treatment, both of which have little to no data to support that they actually do anything worthwhile for a gun barrel.

Of course, all of this information is not really certified factual, its just what I read on the internet.

 

[R.W.Dale]

I've had ADCO reprofile a few barrels with no issues whatsoever. In fact I'm about to send them another.

I have no compunction about recommending them 100%

Every ar barrel on the market is profiled after being rifled. This is an utter non issue

 

[Art Eatman]

Bo Clerke, now deceased, turned out match target barrels, mostly in .17, .204 and .22. I saw a box of his barrel blanks. 24", octagon shaped, somewhere at one inch or a bit more.

Re-profile? Yup.

 

[119er]

All I needed to hear, I was being apprehensive because it is a proprietary barrel. Now to decide on contour. I will probably go with their standard medium and either contour or dimple forward of the gas block as well.

 

[MachIVshooter]

Well, I turned this critter from M-4 profile down to .540"



And though I did it to a brand new barrel (no idea what it would have done before), it shoots about the same as any other standard carbine.

 

[jbj]

ADCO is a good call. For the money, you might also look at Black Hole Weaponry, or Ballistic Advantage for light weight barrels.