I bought a MUR-1A Upper Reciever.  They have the Feed Ramps cut into the upper and I'm wondering what I need to ask/look for when mating a barrel to it.  

Do I look for M4 Barrels?  What is the wording I need to find in Barrel descriptions?

I've built two AR's so far but the Upper Reciever and Barrel came matched.  One RRA parts and One Olympic.  I have One with the feed ramps in upper and one without so I didnt learn much about what to look for.

Thanx in advance for info and sorry If the answer is obvious. hehe
    Mike

Make sure it has M4 feed ramps.

Thanx, now whats the difference between an M4 barrel and an M4A1 SOCOM barrel?

Quoted: Thanx, now whats the difference between an M4 barrel and an M4A1 SOCOM barrel?

The SOCOM barrel is heavy under the handguards so that it can handle full auto fire better.

Don't forget that what you need is M4 ramps on the barrel extension, not necessarily an M4 profiled barrel.  These days you can get pretty much any barrel config you want with an M4 extension.

Quoted: Quoted: Thanx, now whats the difference between an M4 barrel and an M4A1 SOCOM barrel? The SOCOM barrel is heavy under the handguards so that it can handle full auto fire better. Don't forget that what you need is M4 ramps on the barrel extension, not necessarily an M4 profiled barrel.  These days you can get pretty much any barrel config you want with an M4 extension.

I saw that thanx.  The best place I've found so far for clearly describing their barrels is CMMG by far.  I'm learning though so thanx all for the info.

Quoted: I saw that thanx.  The best place I've found so far for clearly describing their barrels is CMMG by far.  I'm learning though so thanx all for the info.

It doesn't help that some places call them "M4 feed ramps" and others call them "extended feed ramps.

adcofirearms.com/acc/ProductLine_.cfm?product_category=Barrels&subcategory=5.56%20Barrels the White Oak barrels towards the bottom have M4 extensions as optional
I think all of the barrels at global-tactical.com/index.asp?PageAction=VIEWCATS&Category=58 have the feed ramps.  

Also, I'm pretty sure that LMT and Noveske use the feed ramps on all of their barrels, but I could be mistaken.

Those are off teh top of my head, there's plenty of others.