I just found a complete upper with 11.5'' barrel with perm. attched 5.5 FS on it.

It is marked "pre-ban", is used, and has A1 sights.  It is Olympic.

My guess is that it is of pretty decent age.

What should I expect in terms of twist rate?  Would it be silly to assume it is chrome lined?  

Ideally, I'd want it to have a 1/9 or 1/7 twist and be chrome lined but I know nothing about these XM177 style uppers.  I had NO intention of getting one but this is just a STEAL @ $120 and the guy insists its in great condition.

What am I missing?  What do I have to be afraid of?  Did they always make these barrels in certain twist back in the day?  

Please educate me.  I bought a pre-ban lower (Damn CT AWB) over the summer and was going to wait a good while and build my dream upper.  Well slap my ass and call me Susan, I can buy this upper and get her "up and running" a year ahead of schedule while I work on getting the custom upper.

What am I missing here folks?  Olympic 11.5''/5.5''FS "pre-ban" complete upper, minus bolt/carrier, for $120.  

If it is cast, do I have a safety issue?   This is driving me nuts, I don't know a damn thing about this thing and I cant pass it up... and I need to tell the seller tomorrow if I'm game.

- BUCC_Guy

(I spoke with the seller on the phone... he will get his hands on the upper himself by monday since it is still inbound to him.  He couldn't help me with this info)

EDIT:  Now I'm so flustered, I don't even remember if it is 10.5 or 11.5 inches.  Argh

Chrome moly 1/12 or 1/9, check for markings in front of the front sight base. I dont think Oly cast any uppers, but even then its not a safety issue. If it is not beat to shit you should definitely buy it. Oly has a lifetime warranty and will service it regardless of age, or original owner.

Forgot to say, first thing you need to do, after the bolt carrier group, is put a new sight aperture in, with a ghost ring and small aperture on the same plane, insead of two small apertures. I think A1 also has the sights on a different plane, for different zeros to compensate for range. Also buy an A2 front sight and the sight adjustment tool to go with it.

My 11.5 ich Oly barrel has "5.56 SS" stamped under the FSB.  This indicates that it is stainless steel and those barrels were 1/9 twist.  Check out their website.  Olympic Arms has a page there on identifying their barrels from makings.  
Hope this helps, Hoddie.

Thanks for the info guys.

I use Federal mil-spec 55g.  Is this going to be OK if its a 11.5'' with 1/12?

I checked ammo oracle, couldn't get a concrete reference.

Max range usage would be 200 yards.   99% of the time would be 10 to 50 yards.

- BUCC_Guy

Quoted: Yes, a 1:12 twist will stabilize ammo up to 55gr reliably. -Troy

Even in an 11.5 barrel?

This would relieve me of most hesitation with the purchase.

- BUCC_Guy

Quoted: Quoted: Yes, a 1:12 twist will stabilize ammo up to 55gr reliably. -Troy Even in an 11.5 barrel? This would relieve me of most hesitation with the purchase. - BUCC_Guy

That's what it was originally. It'll be fine. The only thing the shorter bbl affects is velocity.