Does anyone have a list of the ar15 gas port size specs for the various barrel lengths and any differences for the differnt calibers if there is any? port locations for various lengths? I am also looking for blueprints for the ar15 barrels which would include some of this major and minor specs for rebarrekling ar's.
Thanks
Considering that AR-15s are commercially chambered for over two dozen different cartridge, five standard or semi-standard gas port positions, and five semi-standard barrel diameters at the gas port location you're going
have a very long list. That's not considering that often the gas port size is taylored for different loads and bullets used in a particular cartidge. A good example of that is the 300 Whisper where two gas port locations and diameters are offered by the same manufacturere specifically for subsoinc and supersonic loads. Some manufactueres offer adjustable gas block for such rifles.
There is some information along the lines you want at
http://www.ar15barrels.com and htttp://www.ar15.com but I doubt you ever find the list you're seeking. You'll only find an occasional mention of the gas port size used on a specific barrel. That's a variable many manufacturers use to tune the rifles they build, and gnerally not something to be specified in a procurement contract even for "standard" military rifles.
You have several choices if you're building a rifle for a special load or wildcat cartridge. You can get an adjustable gas block or gas tube, or use a "numbered drill set and tune your barrel to the load your using. If you then bulid a second rifle for the same cartidge and load then you know what to use. If you can find a rifle someone already has which matches what you want they they may let you measure the port diameter. Beware, the barrel cartidge and load need to be identical.
There are discussions on tuning barrels to loads on sites which deal with subsoinic cartridges. It's mostly a matter of guessing the gas port location from studying pressure curves as calculated by programs like Quickload then adjusting the port sizes and some asking others what they've found works with similar cartridges. It's not an exact science.
I "built" a pair of matched left and right hand 300-221 pistols where I specified the barrel length and asked the barrel manufactuer only put an index mark at my specified gas port location. I worked up the port size with a number drill set using my handloads until I was happy with the cycling in the first barrel, then drilled the second barrel the same. That worked well taking only eight test shots. The barrels are identical even though the upper receivers are not.