December 16, 2011
By George Spafford
George Spafford is building a replica of the Yugo M70B rifle using a stub parts kit. A new installment will appear here every Friday
Install the Fire Control Group and Internals
Spafford used a fine 3M abrasive pad to polish the back of the hammer as well as the upper and lower rails. One of the reasons AKs need to wear in is to remove the irregularities on the back surface of the hammer where the carrier rides over it. By polishing, everything is smoother from the start.
From here, you need to assemble the rifle. I recommend polishing both the upper and lower rails to remove any burrs. I also polish the back of the hammer and the surface of the hammer where the hooks grab. Note — the intent is only to polish. If you remove too much material, you can alter the geometry of the fire control group and impact functioning.
When people buy new AKs or build an AK for the first time, they complain of sticky actions where the bolt carrier seems to hang on the hammer. Most of the time, this is a matter of wearing in and lubrication. I use CLP on the FCG and dabs of wheel bearing grease on the rails, back of the hammer, sides and bottom of the bolt carrier. This makes for a very smooth action when coupled with the polishing. In all cases, AK actions tend to get smoother as they wear in, so even if you skip this step, the action will improve with time.
I install the hammer and use needle-nose pliers to locate the spring. From there, I install the trigger. Be sure the disconnector spring is installed. Failure to install it will result in inconsistent fire control group functioning.
This is the installed TAPCO G2 FCG, Falcon Arms spring set and Romanian G selector lever. It's not visible from this angle, but the Falcon FCG retaining spring was used. By using all new Falcon springs, any potential headaches caused by worn-out springs are avoided.