Ammo for AR-15 Range Practice: How to Choose

To choose ammo for AR-15 range practice, match three things: the chamber marking on your barrel, your barrel's twist rate, and the rules of the range you shoot at. For most AR-15s marked 5.56 NATO or .223 Wylde with a 1:7, 1:8 or 1:9 twist, a 55 grain or 62 grain full metal jacket load is the usual practice round. If your range bans steel-core bullets, pick a conventional FMJ such as a 55 grain .223 instead of M855. Everything named below is on our shelf at our Phoenix warehouse.

Step 1: read the chamber marking

The barrel marking decides what you can feed the rifle. A barrel marked 5.56 NATO fires both 5.56 and .223 Remington. A barrel marked only .223 Remington should get .223 unless the rifle maker approves 5.56. Federal's technical bulletin explains why: the leade, or throat, in a .223 Remington chamber is usually about .085 inch, while a 5.56 chamber's leade is typically about .162 inch. Military-spec 5.56 also runs at higher velocity and chamber pressure. SAAMI lists 5.56 military ammunition in a .223 Remington chamber as an unsafe combination.

The .223 Wylde chamber, designed by Bill Wylde, is a hybrid. It keeps 5.56 case dimensions with a tighter throat for accuracy, and barrel makers rate it for both .223 and 5.56. Our 5.56 vs .223 answer has more on markings.

Step 2: match bullet weight to twist rate

Twist rate is how far the bullet travels down the barrel to make one full turn, and it is often stamped near the muzzle. Faster twist stabilizes longer, heavier bullets. Common rule-of-thumb ranges:

• 1:7: made for heavier bullets, about 62 grains and up.
• 1:8: handles roughly 55 to 77 grains.
• 1:9: handles roughly 55 to 69 grains.
• 1:12: meant for light bullets, about 40 to 55 grains. A 62 grain M855 bullet may not stabilize, which shows up as oblong or sideways holes in paper.

Every barrel is a little different, so shoot a few groups before you buy a case of one load.

Step 3: check the range rules

Many ranges ban steel-core bullets because they can damage steel targets and backstops. M855 and SS109 have a steel penetrator inside a brass case, so they are steel core even though the case is brass. Some ranges and classes also ban bimetal jackets and tracers. A magnet on the bullet tip tells you what you have. Training schools publish their own rules. For example, Gunsite Academy in Paulden, Arizona lists 1,000 rounds of ball ammunition for its five-day 223 Defensive Carbine course and does not allow M855, tracer, armor-piercing or bimetal ammunition. Read the course listing before you buy.

The AR-15 practice ammo we stock

• MKE 5.56 SS109 62 grain FMJ battle packs: factory new. MKE's catalog lists a brass case, Boxer primer and a bullet of gilding metal over steel and lead cores, with a rated velocity of about 3,000 feet per second measured at 23.7 meters. MKE packs 30 rounds per cardboard box and 15 boxes per sealed PVC bag, which is our 450-round battle pack (13.5 pounds). We also sell 2,250-round cases (67.5 pounds).
• BVAC remanufactured Lake City M855 62 grain FMJ: 500-round packs, 15.0 pounds. It is loaded on once-fired Lake City brass, so it is remanufactured, not factory new. See remanufactured vs new ammo.
• Federal American Eagle XM855 62 grain FMJ: factory new, in 150-round (4.5 pounds) and 600-round (18.0 pounds) packs.
• PMC Bronze 223A 55 grain FMJ-BT: .223 Remington, factory new. PMC rates it at 2,900 feet per second. Packs of 20, 200, 500 and 1,000 rounds (the 1,000 weighs 27.8 pounds).

The first three are 62 grain SS109/M855-type steel-core loads for 5.56 chambers with 1:7, 1:8 or 1:9 twist. PMC Bronze 223A is the pick when a range or class bans M855, and it runs in .223, .223 Wylde and 5.56 chambers. Browse 5.56x45mm NATO and .223 Remington.

How much to buy

For a class, use the round count on the course listing and bring extra. For regular practice, buying by the case keeps one lot of ammunition through many range trips, so your zero and groups stay consistent. Shipping is charged by weight and never free, and orders ship UPS Ground from Phoenix within 2 business days. Check where we ship. In the Phoenix area, call 480-623-4515 and pick up Monday to Friday, 9am to 5pm, with ID. You must be 21 or older to order. Arizona shooters can also find us at Arizona gun shows.

AR-15 practice ammo questions

Is M855 or 55 grain .223 a better fit for AR-15 practice?

It depends on your barrel and your range. M855 is a 62 grain steel-core load that suits 1:7, 1:8 and most 1:9 barrels. A conventional 55 grain FMJ .223 load suits nearly any AR-15 twist and is allowed at ranges and classes that ban steel core. Many shooters keep both.

Can I shoot .223 ammo in a 5.56 AR-15?

Yes. .223 Remington is safe in a 5.56 NATO chamber. Federal notes you may see a slight loss in accuracy and velocity compared with a .223 chamber. The reverse, 5.56 in a .223-only chamber, is the combination SAAMI lists as unsafe.

Is remanufactured 5.56 OK for range practice?

Many shooters use it for practice. It is loaded on previously fired brass, so check that your rifle's maker allows it. Our BVAC M855 is labeled remanufactured on the product page.

How should I store a case of AR-15 ammo in Phoenix?

Keep it indoors in sealed packaging or an ammo can, away from closed cars and uninsulated garages, which get far hotter than the house in a Phoenix summer. See how long ammo lasts in storage.

More in our 5.56 NATO guide, the .223 Remington guide and our ammo FAQ.