Hi everyone, y'all have been loads of help for newbies like me. I've been reading the forums, TM's and studying pictures for weeks and finally started getting parts for my first build. I thought I had things squared away so far but suddenly got confused with the whole .223 vs 5.56 issue. I have so far a Colt surplus barrel ass'y (NOS, 20", thin, triangle guards), an A1 upper receiver (no internals yet), and ordered the RRA U.S. marked lower from LT.
My question is this; I don't see any markings on the barrel or upper as to their caliber - what can I check/measure to verify what it is? Also, what do I need to keep in mind for my build if I want to gear it toward the 5.56? and do i really need to concern myself with the .223/5.56 difference for just a shadetree shooter?
I will have to install the barrel onto the receiver and plan on getting a new bolt/carrier assembly so what are the chances of the headspace being wrong? and does that relate to the .223/5.56 issue at all?
Thanks a bunch for any thoughts and suggestions!
[url]www.ammo-oracle.com[/url] The Ammo Oracle has the answer! The short version is no, it shouldn't matter to you. 5.56 chambers are a little looser than .223 chambers, but as a practical matter it's almost the same thing. Either way, it's not a headspace issue.