...or virtually nothing.

Is there a consensus on procedures for breaking in a new AR-15 stainless-steel barrel?  Or just shoot it and clean it when you get home?  Or clean it at the range after each...say...15 - 20 shots?

I recall the break-in procedure for my 6.5-284 target barrel was rather long and cumbersome, but I don't remember what it was, exactly.

It's a 6X45mm FWTW.

Set up rifle at bench.
Fire 2 shots.
Run patch with butchs bore shine through.
Run dry patch through.
Repeat twice.
Should be g2g.

For a new ar15 barrel, I usually just clean the chamber with a chamber brush and hoppes, then run a couple wet patches down the barrel, followed by dry patches until they come out clean.
If I remember, I'll bring the bore snake to the range and pull it through after 5 or 10 rounds.
After that, not much other than regular cleaning.

Opinions vary.

My opinion is to just shoot it. A lot.

I clean with chamber brush and boresnake on a new barrel, same procedure as after the range. Nothing fancy.

I worry that a new gun might somehow have grit or chips inside so I like to wet patch then dry patch a couple of times just to cover that.

The whole thing of "breaking in" a barrel comes from the super hard core target guys and their high end custom hand lapped barrels. Actually those guys can't agree on proper precedure
but at any rate most agree that not much is needed with standard factory barrels.

Some make the case that a new barrel could tend to copper foul a bit so it couldn't hurt to give a good cleaning with a copper solvent such as Sweats 7.62 or Butche's bore scrub
the first few times you shot it.

This. It could be debated till the son goes down.

There's typically all kinds of gunk in the rifling of a new barrel (oil, grease, shavings, dust, what have you) so the first step is to run a wet patch followed by some dry patches to get all that debris out.  Start with a clean barrel.  

At the range, I typically just run a bore snake after every round for the first 5 rounds, then every 5 rounds for the next 20 rounds; basically just to lay down a layer of copper without any other debris.  
Then I just shoot the shit out of it and run a bore snake through at the end of the day.  That's it, no further cleaning until accuracy starts to degrade.

Just shoot it, unless you are planning on shooting quarter-minute groups with it.

If it is just an ordinary rifle, treat it as such.

This.

Just clean the machining debris out of the barrel and clean it every few rounds if you like.  As mentioned, unless its a dedicated PR, no special attention is really needed.  I generally will shoot about 5 rounds then use a copper solvent and a brush for a good cleaning then shoot the piss out of it.  I have seen some manufacturers recommend cleaning after every round for the first 5.rds then after every 5 rds for the first 100.  Seems like overkill to me and the more you run that rod down the bore, the more chance you have of scratching it.  Some are of the opinion that these scratches will help prematurely wear the barrel which allow the manufacturers to sell more barrels.  Its an evil corporation plot I tell ya!  Where is my tin foil, I need to make a new hat.

It isn't a real thing.

This is how I do it

Break-in is to achieve copper  equilibrium.

A break-in procedure is to build up that copper equilibrium so that your barrel can go longer without building up too much copper in the bore.

This is especially true with mass-produced barrels.

It also  attributes to easier cleaning of the boar in the long run.

It may also give the barrel longer life.

Hand lapped barrels have already been smoothed out and it has been my experience that the break-in procedure is almost not necessary but if done, can be achieved in a shorter period of time.

I purchased two criterion hand lapped chrome lined 1/8 twist barrels, and broke one in and did not bother to break in the other and I noticed absolutely zero difference between the two as far as accuracy and cleaning go.

Of course breaking in a AR 556 chrome lined barrel seems to be counterproductive. In my opinion though, it probably does help smooth it out a little bit as there are probably small chunks of chatter and imperfections from the machining of the bore.

Hand lapping is supposed to take all that away from the get go.

All that being said of course I can remember reading an article  about how a certain barrel manufacturer started this whole break-in thing in order to get people to wear out their barrels  faster and therefore sell more barrels.

Myth? Who knows?

Of course this is just my opinion and we all know what opinions are like..

Search
"gale mcmillan on barrel break in"

Check with your barrel manufacturer.

For most barrels I would agree no break in (but clean before shooting first time).

Since you say stainless, I would assume more of a "match" type barrel (?), if so, see what the manufacturer recommends.  I believe that most match type barrel makers do recommend a break in period/technique, and they do vary widely.

all these posts with bore snakes...i thought i recall reading alot of bad press on those. no?

OK, time to stop!  

I'll clean it at home, and take the time to run a couple patches of SLIP2000, my usual c/l/p, thru the bore each 10 or so shots the first time I have it at the range.

I thank each of you for your contributions, and I'm really glad I don't have to perform some long-and-complicated break-in ritual.  

There is no statistical proof that breaking in a barrel does anything except help start wearing it out.

This. One of the more successful myths in the industry. Right up there with "stopping power".

Ask yourself what you hope to accomplish (or expect to accomplish) by the end of the break in? Once you know that answer, then find the method to measure such thing.

i have a hard time believing that running cloth patches through a barrel wears out anything. that little projo traveling at Mach 4+ will do more damage than any cloth patch or even brass brush.

Who's son?


Shoot clean repeat.

You haven't lived till you've seen a brush wear grooves into a barrel like a phonograph needle.

I think the issue is more brushing the bore too much or damaging the crown than the cloth doing anything.

Just shoot it.

I have a very detailed process I use on every rifle I own.

Hah, no.

Do what feels right for "you". You'll get a million opinions.

Do what the make of the barrel or rifle says to do. Most everyone is different. Don't waste time listening to the hundred you'll see here and other places. Ask the maker. At least you can say that you followed their instructions, whether or not they are better or worse than any other technique.

From compass lake web page.

NEW BARREL BREAK-IN PROCEDURES

Your new barrel will shoot best if careful attention is given to a proper break-in.  Differing opinions exist; however, we recommend that no more than 20 rounds are fired at the time before cleaning the barrel for the first 60 rounds.  Your barrel must be thoroughly cleaned each time for the first 120 rounds.
Procedure for thorough cleaning:  in all cases, it is vital that cleaning tools (brushes, patches, etc.) be pushed from the breech to the muzzle and then removed from the end of the rod at the muzzle end.  DO NOT drag anything back through the muzzle.

Clean the bore with JB Bore Cleaner after 100 rounds as follows:
1.  Work the JB into the patch.
2.  Wrap the patch around a worn bronze bore brush (not nylon).
3.  Using a bore guide, stroke back and forth for 5 strokes in the first half of the barrel.  (Breech Half)  Push patch through the muzzle and unscrew brush from rod and carefully remove rod from barrel.
4.  Remove old patch from brush.
5.  Repeat steps 1 - 5 for 5 complete cycles.
Note:  A neglected barrel may require this to be repeated for many more cycles until it is smooth.  
Note:  The patch will never come out clean as JB is a slightly abrasive compound and is working to polish your throat and bore.

CLEANING AND LUBRICATION
After the barrel is broken in, clean the bore immediately each time after the rifle is fired.  De-copper the bore and use JB bore cleaner every 200-300 rounds.  Field strip and clean the bolt carrier assembly.  Use a patch soaked with bore cleaner to clean the bolt carrier bore and the bolt face and stem.  Dry all parts and lubricate bolt locking lugs, gas rings, and bolt stem with CLP and reassemble the bolt carrier, while lubricating the cam pin and firing pin with CLP during the process.  Clean out the inside of the upper receiver with a paper towel or patch; lubricate the charging handle, support rails of the bolt carrier, and the inside of the bolt carrier key.  Reassemble.

Note:  The entire cleaning process is much easier by bringing a rod, patches, and bore cleaner to the range with you.  As soon as you are finished firing the rifle, break the rifle open, remove the bolt carrier assembly, run a little bore cleaner into the two gas vent holes in the dish on the right side of the bolt carrier.  Pump the bolt back and forth a few times to distribute the bore cleaner. This will soften the carbon in the bolt carrier and make it very easy to clean once you get home.  I also suggest that you run two patches soaked with bore cleaner through the barrel and allow it to soak until you get home and then do a thorough cleaning job.

TRIGGER ASSEMBLY
The trigger assembly requires little attention.  Occasionally lubricate the trigger and hammer pins with a drop of CLP.  The trigger engagement notch in the hammer should be lubricated with Neco Moly Slide every 6 months.  Trigger adjustment is seldom required.  If it becomes necessary to increase the weight of the pull, use this procedure:

Increase sear engagement by screwing long spring plunger in the safety in approximately 1/20 of a turn using a pair of needle-nosed pliers.  It should not be necessary to loosen the lock screw.  If the trigger is still light, increase the weight of the second stage pull by turning the small set screw in the top of the spring plunger.  Use a .035” allen wrench.
The other set screw in the safety is the over-travel stop.

This. I've never understood how running a brush or patch through a barrel is "breaking it in" vs. running a 55gr projectile at 3100 fps doesn't?

I built a Mk 12 (a "precision" AR), and I didn't even run a patch through the barrel. I lubed the BCG and have put about 300 rounds through it without cleaning it. Shot a 1" group at 300 the other day. [shrug]

YMMV.

Armalite used to have a break in procedure for their national match, stainless barreled rifles, but since the new people have taken over the company, I can't find the online link.
It was a tedious process, best done when you had the range to yourself, and lots of time and patience.