Our Hard Blue barrels usually require about 60-80 round before the barrel is fouled enough for the groups to tighten.  Just about all my barrels, whether on a Garand, M1A, bolt rifle, or .22LR group better when fouled.  I am not talking about a filthy barrel, just a fouled barrel.  No need to de-copper unless the accuracy starts to fall.  SB_Matt has a barrel with 1900-2000 rounds through it; never de-coppered; groups remain the same.  I de-coppered one of mine, and it took 60 rounds to get it back where it was.  After 200 rounds, it went back to half minute on a good day for me; 3/4 to 1 minute when my tremors were acting up.  I've had a few of our barrels shoot the same from the first bullet.  Remove the carbon though; sometimes I do, sometimes not.  Always clean your receiver, bolt, and bolt carrier (and associated guts).  Keep Teflon OUT of the chamber and bore; nothing screws up groups like PTFE.  Learned that from several High Masters.  Never been a fan of the stuff; burns at 400F, give or take, and those deposits are horrible: black caked compound.  SB_Matt and I were using a registered full auto lower with its owner one day when we were doing C-mag dumps (and a gas tube will fail at 175-225 rounds, with one pull of the trigger....after all, is not full auto for me unless I pull the trigger just once).  Anyway, in between mag changes, the lower owner kept spraying something in the upper.  After 400 rounds, the bolt carrier froze half way closed.  Upon investigation, the receiver was 320F degrees (infrared thermometer) and black caked compound was all over the place.  Turns out it was cooked PTFE.  PIA to clean out too.  Anyway, we learned two lessons that day: 1. friends don't let friends spray PTFE in the upper, and 2. fire fighting gloves work on aluminum free float tubes too.

Federal 69 grain works well.  Edited to add: we got one lot of this ammo that did not shoot so well; came in right at a bit over one MOA.  The Sierra 69 grain bullets have always performed well.  There is just something about that bullet that makes it fly right.

Hornady 53 grain works well too.  Out to 200 yards, it seems that flat based bullets tend to shoot a tighter group.  At 300 yards, its a toss up depending on the bullet.  Past 300 yards, BTHP match every time wins it.

We have a lot of Black Hills, red box, 75 grain that shoots 1.75 MOA.  I don't know what it is about this particular lot: not so good.  One polygon Terebratus upper we built shot it very, very well.  Go figure.  Out of eight uppers targeted that day, only one like it.  Seemed odd to us.

We've shot some BH, red box, 60 grain, ammunition that was spectacular.

We have limited success with any manufacturers' loads using Sierra 77 grain.  We can't get much better than a minute out of that bullet.  However, the Federal 80 grain ammunition is right on.

53 grain flat base (Sierra and Hornady) has shot extremely well.  I prefer a flat base bullet out to 300 yards.  I need to get busy and swag some flat base 75-79 grain bullets, just for fun.  I've had OK results with my swaged bullets using .22LR cases, but the will come apart right around 3000 FPS.  When shot at 2600-2900, all energy is expanded within a few inches in the target.

I have never gotten the Sierra 77 to shoot well.  Of the heavy bullets, the Hornady 75 grain HPBT match (not AMAX) and Sierra 80 grain shoot very well.  I use IMR-4895.  It seems that the slower burning powders (IMR-4895, Varget, N-135, N-133, N-140) work best with heavier bullets; may have something to do with the slower burn and thus the longer time before maximum pressure is reached.  I do not use a compressed load, and I use QuickLoad, set at 122F degrees, to calculate loads; I try not go above 55,000 PSI.  I run the program at the highest temperature setting, because after firing five shots the chamber is heated enough to rapidly transfer heat to the case, and the pressures increase accordingly.  The most accurate loads I have gotten with every caliber have been ones that are about 15% less than maximum/factory pressures.  I figure that the target doesn't know the difference of 200-300 FPS: all hits count.  I'd like to have flash x-ray speed photography coupled with pressure gauges to see how this may work out: bullet position versus pressure.  I may give APG a call about that.

The only barrel I've seen Sierra 77 shot well from was a 24" 1:7.7 Krieger.  The owner never shot more than three rounds at a time...and then left the bench tied up for another 30-40 minutes while it "cooled down".  He tied up the bench for 3.5 hours and shot 21 rounds....not that everyone else waiting to use a bench was angry or anything.  He is an ass.  Anyway, there may be something about the Krieger 1:7.7 that makes the 77's shoot well.

I loaded some 5000 Sierra 55 grain Blitz King (whatever the polymer tip varmint bullet is named) to maximum pressures at 122F degrees, using TAC at a OAL of 2.250".  These shoot well; usually 0.75 MOA, sometimes I can get them to group down to half minute, but that is a rare day; I just can't shoot as well as I could 30 years ago.  Anyway, after 30-40 rounds, I am wasted and lucky to hold a minute using the best of rests.  And if the temperature is 80F degrees or higher, I am lucky to get 20 rounds off well.  I thought 30 y/o was tough, then 40, and now 50 takes the cake.

Edited to add:
I cannot remember trying the Nosler 77's.  I've made a note to buy some from Midway.

Breaking in your Superior Barrels barrel

"Barrel Break-in and Cleaning

The break-in process is very simple, for barrels without Hard Blue.

Fire a few shots, clean, keep firing.

If you want, you can shoot once, then clean, for 5 rounds, but there is no benefit.  You will spend your day cleaning and not shooting, and that is what a properly made barrel should do: shoot.

Hard Blue barrels need nothing.  Generally, you will need to fire about 20-50 rounds to get the groups to tighten.  De-copper when you note your accuracy falling off.

Cleaning:

If you use a solvent containing ammonia (Butch's Bore Shine), the barrel should be also cleaned with a non-ammonia solvent to remove the ammonia.

NEVER use a stainless steel brush!  Clean from the chamber end.  Use a bore guide.  Use a one piece cleaning rod, either coated or carbon fiber.  We recommend using either a high-quality bronze brush with a wire core of copper or aluminum (not steel) or a nylon brush with the same type wire core, a brass jag, and a chamber brush or mop.  Ed's Red, Butch's Bore Shine, Remington 40X Bore Cleaner, and Mobile 1 are all excellent products to clean and lubricate your firearm.  It is what we use and recommend."

Also the Hoppe's Boresnake works wonders too.

Hard Blue barrels do not act like any other barrel, not like chrome lined, chrome moly, or stainless.  The finish is very smooth and very slick.  The main thing you will notice is that the throat stays the same for thousands of rounds.

If you de-copper, you will need to fire approximately the same amount of rounds to tighten the groups again.  Most of my barrels (all types) shoot better fouled, than when they shoot clean.

I look forward to your range report.

When switching between bullets or powder, and even sometimes primers, the groups and velocities will not settle for the first 5-10 rounds.  I think that it has to do with the amount of drag caused the the various combination of jacket, powder, and primer residue in the bore.  After 5-10 rounds, the drag begins to stabilize and thus, remains the same, more or less, and thus the bullet is launched the same with each shot.  The thing that may change velocity is the temperature of the chamber and how long the round stays in the chamber before firing.  The longer the round is left in the chamber, the more heat is transferred to the round.  The more heat transfer, the higher the chamber pressure, and thus, a change in velocity.  For a very loose guideline, for each 10F degrees increase, chamber pressure increases 1000 PSI.....very loose guideline.  Consistency is the key to accuracy.  OK, this was a bit over the top.  I'm blaming my rum and cola on that.  

Edited to add:
Run a box test on your scope when you first get it, just to make sure its working correctly.  I blame the omission on the rum and cola, again.  

It does look a bit confusing the way I wrote it.  Thanks for pointing that out.  I changed the page to read better....I hope.  Usually, the directions are on the solvent bottle.  Butch's says to run a dry patch to remove and follow with "Butch's Gun Oil".  Ed's Red, Mobile 1, or Kroil work well.  For me, the main thing is to remove the ammonia, without using an ammonia containing cleaner.  This sounds weird; I've seen it done though.  Watched one shooter use undiluted 10% cleaning ammonia, AFTER using Hoppe's #9....he said it will "eat out" what the Hoppe's missed.  I bet it did.