Dimensions & Measurements
Most of this information is originally from the AA-OK Tech Info Page and from spot measurements of different barrels.
Gas Port Sizes
| Caliber | Angle | Diameter | Bit Size | Breech Distance |
| 7.62x39 | 45 degree | .177" | # 16 bit | 11.625" (11 5/8") / 295.275mm |
| 7.62x39 | 90 degree | .177" | # 16 bit | 11.9063" (11 29/32") / 302.420mm |
| 5.45x39 | 90 degree | .076" | # 48 bit | 11.9063" (11 29/32") / 302.420mm |
| 5.45x39 AKS-74U |
90 degree | .070" | # 50 bit | 7.1305" (~7 1/8") / 181.115mm |
| 5.56x45 Saiga | 90 degree | .067" | # 51 bit | 11.9063" (11 29/32") / 302.420mm |
| 5.56x45 Galil |
30 degree | .073" | # 49 bit | 11.718" (11 23/32") / 297.658mm |
| 7.62x51 Saiga |
90 degree | |||
| 7.62x51 Yugo |
45 degree |
Barrel Thread Sizes - Muzzle
| Caliber | Size x Pitch |
| 7.62x39 | 14mm x 1.0 LH Thread |
| 5.45x39 | |
|
|
| 5.56x45 Saiga | n/a (threads on FSB) |
| 5.56x45 Galil | 13mm x 1.0 RH Thread |
| Saiga-12 | 22mm x 0.75 RH Thread |
Journal Sizes
7.62x39 Caliber
| CHINESE AK BARREL: | O. D. DIMENSIONS |
| Chamber .764" | (19.25mm w/ .005 - .006" press fit) |
| Rear Sight Base .734" | (18.5mm w/ .005 - .006" press fit) |
| Handguard Retainer .691" | |
| Gas Block .634" | (16mm w/ .003 - .006" press fit) |
| Front Sight Base .594" | (15mm w/ .003 - .006" press fit) |
| CHINESE AK BARREL (threaded): | |
| Chamber .903" | (22.95mm) |
| EURO AKM PATTERN BARREL: | |
| Chamber .908" | (23mm w/ .003 - .004" press fit) |
| Rear Sight Base .694" | (17.5mm w/ .003 - .004" press fit) |
| Handguard Retainer .671" | |
| Gas Block .594" | (15mm w/ .003 - .004" press fit) |
| Front Sight Base .575" | (14.5mm w/ .003 - .004" press fit) |
| YUGO M70 PATTERN BARREL: | |
| Chamber .908" | (23mm w/ .003 - .006" press fit) |
| Rear Sight Base .730" | (18.5mm w/ .003 - .006" press fit) |
| Handguard Retainer .687" | 8.4375"/ 214.31mm from breech face (8 7/16) |
| Gas Block .630" | (16mm w/ .003 - .006" press fit) |
| Front Sight Base .593" | (15mm w/ .003 - .006" press fit) |
| YUGO M92 PATTERN BARREL: | |
| OAL: 10" (subtract .015" recess at FSB) | 254mm |
| Chamber .907" | (23mm w/ .003 - .004" press fit)Hinge Block |
| Hinge Block .736" | (18.694mm w/ .002 - .004" press fit) |
| Handguard Retainer .687" | 7.375" / 187.3mm from breech face |
| Front Sight/Gas Block Combo Base .591" | (15mm w/ .002 - .004" press fit) |
| ROMANIAN AKM PATTERN BARREL: | |
| Chamber .908" | (23mm w/ .003 - .006" press fit) |
| Rear Sight Base .691" | (17.57mm w/ .003 - .004" press fit) |
| Handguard Retainer .668" | 8.25" / 209.55mm from breech face (normal) |
| Gas Block .593" | (15.07mm w/ .003 - .004" press fit) |
| Front Sight Base .573" | (14.57mm w/ .003 - .004" press fit) |
| ROMANIAN RPK PATTERN BARREL: | |
| OAL | mm |
| Chamber .908" | (23mm w/ .003 - .006" press fit) |
| Rear Sight Base .884" | (22.45mm w/ .003 - .004" press fit) |
| Handguard Retainer .863" | 8.0938" (8 3/32") / 205.58mm from breech face |
| Cleaning Rod Retainer .756" | 15.6875" (15 11/16") / 398.46mm from breech face |
| Gas Block .789" | (20mm w/ .003 - .004" press fit) |
| Front Sight Base/Bipod Base ." | (mm w/ .003 - .004" press fit) |
5.45x39 Caliber
| AKS-74U BARREL: | O. D. DIMENSIONS |
| OAL 8.3125" (8 5/16") | 211.14mm |
| Chamber .865" | (22mm w/ .001 - .003" press fit) |
| Hinge Block .689" | (17.5mm w/ .002 - .003" press fit) |
| Bottom Handguard Bearing Surface .665" | |
| Handguard Retainer .608" | 6.03" / 153.15mm from breech face |
| Front Sight/Gas Block Combo Base .551" | (14mm w/ .001 - .003" press fit) |
| BULGARIAN AK74 BARREL: | |
| Chamber .871" | (22mm w/ .002 - .003" press fit) |
| Rear Sight Base .694" | (17.5mm w/ .003 - .004" press fit) |
| Handguard Retainer .671" | 7.875" / 200.25mm from breech face |
| Gas Block .594" | (15mm w/ .003 - .004" press fit) |
| Front Sight Base .575" | (14.5mm w/ .003 - .004" press fit) |
| GERMAN AK74 BARREL: | |
| Chamber .867" | (22mm w/ .001 - .002" press fit) |
| Rear Sight Base .694" | (17.5mm w/ .003 - .004" press fit) |
| Handguard Retainer .671" | |
| Gas Block .594" | (15mm w/ .003 - .004" press fit) |
| Front Sight Base .575" | (14.5mm w/ .003 - .004" press fit) |
| ROMANIAN AK74 BARREL: | |
| Chamber .908" | (23mm w/ .003 - .004" press fit) |
| Rear Sight Base .694" | (17.5mm w/ .003 - .004" press fit) |
| Handguard Retainer .671" | |
| Gas Block .594" | (15mm w/ .003 - .004" press fit) |
| Front Sight Base .517" | (13mm w/ .004 - .005" press fit) |
| ROMANIAN SHORT BARREL (AIM): | |
| Chamber .908" | (23mm w/ .003 - .004" press fit) |
| Rear Sight Base .694" | (17.5mm w/ .003 - .004" press fit) |
| Handguard Retainer .671" | |
| Combo Gas Block & Front Sight Base .575" | (14.5mm w/ .003 - .004" press fit) |
5.56x45 Caliber
| SAIGA 223 BARREL: | O. D. DIMENSIONS |
| Chamber .867" | (22.02mm w/ .004 - .005" press fit) |
| Rear Sight Base .768" | (19.5mm w/ .003 - .004" press fit) |
| Handguard Retainer .666" | |
| Gas Block .630" | (16mm w/ .003 - .004" press fit) |
| Front Sight Base .591" | (15mm w/ .003 - .004" press fit) |
| GALIL AR/ARM BARREL (threaded): | |
| OAL 18.1875" (18 3/16") | 462mm |
| Chamber .735" | 21mm x 1.5mm RH threaded |
| Locking Lug .788" | 20mm |
| Handguard Retainer .687" | 8.125" / 206.375mm from breech face |
| Front Sight Base/Gas Block Combo .632" | 16.05mm w/.003" press fit |
| BULGARIAN (KVAR) BARREL: | |
| Chamber | |
| Rear Sight Base | |
| Handguard Retainer | |
| Gas Block | |
| Front Sight Base | |