I have a barrel marked 5.56 near the front sight. How can I ID who made it. It is 24 inchs long. I want to install a flattop upper and make it my varmint set-up. Any help?

Thanks Kevin, here is some info I found at the Olympic web site.

Olympic Arms uses a unique stamping system that identifies it's barrels. You will find these stampings on the barrel itself, just forward of the front sight base assembly. The stampings may be at any angle; top, side, bottom etc. There are many things to be learned from these markings. By reading this information you will be able to tell the twist rate, material type, caliber, and type of rifling. Everything you need to know about your barrel is encoded right there before your eyes. It's just a matter of learning our simple coding system.


CALIBER
First off, every barrel is stamped with the caliber. Since we make over 10 different calibers that are interchangeable on any standard Olympic (or mil any spec) .223 caliber lower, this should be the first thing you check.  The standard .223 caliber rifles are marked "5.56", while the alternative calibers are marked appropriately (45ACP, 40 S&W, 6 PPC, 17 Rem. etc.).

BARREL MATERIAL

CHROMEMOLY BARRELS
The next marking, or lack of it will determine the type of barrel material; in other words, what the barrel is made of. Since we know what to look for to determine the caliber, lets go under the assumption that our barrel is a .223 caliber (5.56), but this same system applies to all calibers. If the only barrel stamping is "5.56", then the barrel is made of 4140 chromemoly steel. Chromemoly is a type steel that incorporates chrome right into the barrel metal itself. This barrel material is corrosion resistant, but not as much so as a stainless material. Using the 4140 chromemoly material allows us to give the consumer a barrel with similar benefits of a chrome lined barrel, but maintain consistencies in the bore that allow for superior accuracy. Our studies have shown that without a doubt chrome lining of any barrel will deplete it's accuracy.

If there are any stampings other than the caliber, they will answer other questions that we will address later.

STAINLESS STEEL BARRELS
If after the "5.56" markings, if you also see "SS", then your barrel is manufactured from 416 stainless steel. This material is very resistant to corrosion, and is universally accepted as one of the best barrel materials available. Even though this barrel is stainless steel, because of it's carbon content it is slightly magnetic. So if you have just tested your barrel and found that a magnet sticks, don't panic, this is normal.

TYPES OF RIFLING

Every barrel that we manufacture is of Match grade quality. In other words, with all of our rifles, regardless of type you should be able to around achieve 1" groups at 100 yards, using a good factory Match ammo or custom handloads. This even includes our 16" guns.