AR15 break-in procedures? 55gr out 1/7 SS barrel ok?

Shoot it.
It doesn't care what weight bullet goes through it.

("...it’s an AR - it’ll be fine....”)

BullHeadedGideon said:

I generally just see people shrugging the question off with, “it’s an AR - it’ll be fine.”

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Yup, it will! But, no harm in asking!

IMHO, just to "Settle it in" shoot what you have.
If you have problems with that particular ammo, try something different.
Don't necessarily worry about accuracy, (but don't just "Blast Away"),,and see how it runs for you.

Once you get it running correctly (assuming you have trouble) THEN try for an accurate load.

In theory at least bullets heavier than 55 gr should be a bit more accurate, but in practice probably not. The most accurate loads I've found are 50 gr and they shoot fine in my 7 twist rifles. It is better to have barrels that are a little faster twist than ideal than too slow. If you had a 12 twist barrel and tried shooting bullets heavier than 60 gr then you'd see less than optimum accuracy. But either way it isn't going to hurt the rifle.

69gr bullets shoot best in my SS 1:7 PSA upper.

Clean it first, shoot it, shoot it some more. Get a bunch of different ammo and shoot that some more and find what you both like, shoot that even more.

Good advice from all.
Just go shoot.

I'd recommend getting 100 rounds of Federal Lake City M855 or M193 for the first rounds.

When new, the Gas Block is a little leaky ( the first dozen or so rounds will seal it with carbon ) and the action tends to be a little stiff. Using full powered ammo, and lubing the action well will help avoid the short stroking I often see on brand new ARs. Other than that, I just brass brush/ patch the bore to get out any manufacturing/shipping debris.

Ramone said:

I'd recommend getting 100 rounds of Federal Lake City M855 or M193 for the first rounds.

When new, the Gas Block is a little leaky ( the first dozen or so rounds will seal it with carbon ) and the action tends to be a little stiff. Using full powered ammo, and lubing the action well will help avoid the short stroking I often see on brand new ARs. Other than that, I just brass brush/ patch the bore to get out any manufacturing/shipping debris.

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I'll second that advice. I always shoot full power M855 or M193 for break-in. I've seen some rifles not function properly with factory .223 rounds when new.

Another thing that I do is to hand cycle the bolt at least a 100 times before ever going to the range with a new upper. It might not be necessary but between hand cycling and using M855 or M193 ammo I haven't had any problems with any new upper (complete or built myself)/

I have a nice BCM stainles steel 16 inch upper with a Geissele Mk1 hand guard. Very accurate rifle with match grade ammo. I shoot mostly M193 and 55 grain 223 through it. Accuracy drops from about .75 MOA to 1.5-1.75 MOA but that level of accuracy still gets me on steel out to 750 yards.

Good ole M193 will be fine in your barrel. Just dont do mag dumps and your stainless barrel will be fine.

IMO you are waaaay overthinking this.

My most accurate AR at the moment has a PSA 16” Nitrate 1 in 7” barrel using PMC 55 gr. FMJ. Sadly the picture of the group I shot with it was on my old cellphone but it put 4 out of 5 rounds inside a dime. The other round was a bit low and was the first shot from a cold, clean barrel.

My biggest disappointment is a AR that has a 16” 1 in 9” Wilson Arms air gauged barrel. I can not get it to group with 55 gr. bullets. I have installed a better BCG and trigger and hammer which have helped some but it is still way below my expectations. I have not tried 62 gr. bullets yet.

Internet wisdom says my results should be the opposite. Wilson Arms barrels are not inexpensive so it should be giving me equal or better groups as the PSA with the same ammo.

For better or worse I took my latest AR build to the range last Tuesday and shot 50 rounds through it to sight in a Romeo5 Red Dot sight. It has a 16” Nitrate 1 in 7” pencil barrel with .625” gas block. Weather conditions were cold and damp so I did not make much of a effort towards accuracy. It was a combination function test and sight-in. This is my first Red Dot sight so I don’t know what to expect from it. I got some Shooters Choice Copper Remover and they do not recommend using a brush with it. So I am cleaning the barrel using the solvent only, no brush, as a experiment.

Nylon brush will help

I have 2 PSA uppers both with 18” SS barrels and I use the same bulk loaded ammo, my own reloads, in every one of my ARs at the range. If you don’t know where to start, grab a box or two of the mildest load you can and a box or two loaded to 5.56 standard and see if it works with both.

Go have some fun already!

Wipe the bore, apply a light coating of oil, buy ammunition, shoot it, then wipe it down, go home, sleep and repeat.

Its designed to handle tens of thousands of pounds of pressure per square inch , contain plasma at thousands of degrees farenheit, and to cycle at hundreds of miles per hour.

Itll be fine

mcb said:

Clean it first, shoot it, shoot it some more. Get a bunch of different ammo and shoot that some more and find what you both like, shoot that even more.

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What this guy said

Over-stabilization only really effects very long range shooting. Over short to moderate distances an over stabilized bullet will have minimal effect on accuracy.

Break-in can be different for different types of barrels. One thing you should do to all new barrels is to clean before you shoot it. In my particular case for a Sanders Armory 6.5 stainless R5 barrel, I was told to shoot my first rounds with Hornady 123 gr SST ammo. Do not clean the barrel until you start loosing accuracy then clean with proper cleaning method. i am sure it could apply to some barrels but not all.

Shoot 'em. They'll be fine.

As mentioned... don't lose sleep over it.

If it was a finely made match , precision barrel... I would spend more time maintaining the bore.

Give that PSA / DC Machine barrel reasonable maintenance, and it will last for a long, long time. Enjoy its qualities... a decent barrel at a working mans price.... many , many thousands of those barrels are in use. I own quite a few PSA / DC Machine barrels, and have had very good experiences with them.

As for twist rates... don't overly concern yourself with that either... your twist rate is a very well respected one.
And can readily handle all sorts of bullet weights .

And FWIW... what looks good on paper, ( twist rates ) rarely translates out so perfectly in the mechanical world... IE , a favorite OEM ammo is ( was ) the 50gr Fed. Tipped Varmint .223... everything about that ammo was wrong as far as "the rules" ... Mass produced brass, bullet ogive WAY from the bore lands and grooves... bulk produced... and danged cheap. ( $5.29 / 20rds was the cheapest )

But that stuff will shoot fantastic 10rd groups out of every danged AR I tried it in... right around 1moa, and bested many more expensive match loads at 100yds.

Honestly, I'd prefer to use the cheap blastin' ammo for barrel break in. Why waste the good stuff?

If you are having function issues, try some NATO spec stuff just to rule out the sometimes under powered Wolf ammo, and to help break in the action. But for barrel break in, as long as it functions, I go cheap as possible. You're just trying to smooth out burrs and such.