im just wondering if the olympic arms barrel (20 & 16") are really good compared to others...
somebody is selling it to me at very "reasonable"price   :->

thanks for the inputs

For what you are asking of the barrel, the Oly will work fine.

Man, ZENIF, lighten up on the caffein...we are all adults here.  There is no need for slamming people when they offer their opinions.

Anyway, what was the original topic again?  Oh yeah, the question was "Is this stuff good?"...My OLY 20" SUM consumes all kinds of ammo just fine, from cheap S. African 5.56, WIN Q3131A, up to hand loaded match ammo.  I'm happy with mine.

AMEN



I have an Ultra Match, marked SUM 5.56, and it really bothers me that I shot some Fed. Lake City 5.56 through it, and found out later it is a .223, guess thats a big No No.
If it is a .223, and there is a possibility of it being damaged by 5.56, it shouldn't be marked 5.56

Rancid

I just bought an Oly Barrel marked "SUM 5.56"
Does this barrel have a 223 or 5.56 chamber?

Go to OlyArms at [url]http://www.olyarms.com[/url] and click the flag; then click tech info; then barrel info.

Oly doesn't update their web site on every change so I suggest you call them at
1-800-228-3471.  

The salient paragraphs are:

Quote.....
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.).


ULTRAMATCH BARRELS
These barrels are our most accurate barrels, and quite frankly, these are the most accurate AR-15 barrels on the market. These barrels have Broach-cut Rifling. What is that you say? Well, broaching is the method used to create the lands and grooves.  For these barrels, we use the stamping "SUM" which means Stainless Ultra Match. These barrels can also be identified by looking down the bore. All of our broach-cut or Ultramatch barrels have only 4 lands and 4 grooves.


ULTRAMATCH BARRELS
Our broached barrels have a standard twist rate of 1x10. Alternative twist rates on these barrels include; 1x8.5, 10, and 14.
......unquote

Oly Chambers:

I bought an Oly kit this summer, with a 'standard' barrel.

Since I wanted to shoot cheap surplus ammo, I asked about the 5.56 issue, and here's what I was told:

"SUM = .223, everything else is now 5.56. We used to make everything .223, but that changed"

It was on their site, and I confirmed it when I called to order my kit.

I had some initial FTEs (about 5 or so in 300rds), but that was probably due to it being a new gun than to Oly's chambering...

Wirebrush said:

The SUM, Stainless Ultra Match has a .223 chamber, held to the tight end of tolerances.
I don't know what ailed them to stamp it 5.56

Rancid

My 20" free floated flattop Oly with SUM will shoot under 1/2" with handloads, and surprisingly, some good groups (3/8"-5/8") greentip S&B, go figure.

I have two other Oly stainless barrels, a 20" Service Match (heavy bbl) and a 16" CAR heavy bbl.  These were purchased in '87 and '90, so they presumably have the tighter .223 chambers.

While many have reported extraction problems with the tighter chambers, I have not experienced any problems in this regard with any of these three rifles.  The only problems I had were when I got first Oly AR, the Oly Service Match, I had a batch of Cooper mags, known for being a problem due to weak springs.  Once replace with other good USGI mags, I have had no  problems with these rifles.

Me too, no extraction problems to date and similar accuracy as stated by everyone here.  The only thing I did to my SUM barrel was polishing its chamber with a little jewel rouge using the good old Dremel (to a mirror-grade shine).  I can say that it was the best $200 ever spent!

Oly SUM's the best value out there in a match grade barrel, I think.  There may be better barrels, but nothing can touch the SUM quality for the cost.