I found this list and thought it could be useful for people wanting to install tightbore barrels:
650mm - PSG1 +
590mm - PSG1 (Std)
550mm - M16A1, A2, VN, AUG +
534mm - SIG550
509mm - M16A1, A2, VN, AUG (Std)
469mm - G3, SG1
455mm - AK47, AK47S
407mm - M4A1, SR16, SIG551 +
363mm - M4A1, SR16, SIG551 (Std)
300mm - M733, MC51 +
285mm - MC51 (Std)
247mm - G36C, P90, CAR15
229mm - MP5A4, A5, SD5, SD6
208mm - G3SAS
141mm - MP5PDW
110mm - MP5K
(found at airsoft Ireland
http://www.airsoftireland.com/forums...showtopic=8237 )
Another more detailed list that I'm to lazy to type out and want copy and paste right can be found here
*Link Removed. It gives the specific company and the barrel length for there guns they are all within a few MM of the first list.
This guide is no longer available it seems. If someone finds it again PM me and I'll re-add it
Sorry if this is the wrong section.