AKS-74u / Krink Hinge Block

Brand new reproduction hinge blocks for the AKS-74u.

These are machined from 4140, heat treated, and come parkerized for protection.
These are clones of a block from an original Bulgarian military AKS-74u kit.
The press fit journal and outside width of the block is sized for standard 5.45 stamped receiver guns (the hole diameter for the barrel is 17.50mm)

Can I use an unmodified bolt carrier with this block?

The bolt carrier hole in the block is 16mm, the same as found on factory AKS-74u blocks. The shaft on a standard AKM/AK-74 bolt carrier has an upper tolerance limit slightly larger than 16mm, meaning that they will often not fit. This is not a defect of your bolt carrier or this hinge block, just an unfortunate consequence of the Soviet design being built with assorted surplus parts nowadays.

The Krink hinge block was not originally intended to be used with an unmodified AKM/AK-74 bolt carrier

However, if your bolt carrier does fit, you're in business! The Version 2 of this block (additonal details at the bottom) has a clearance cut for the corner radius where the bolt carrier shaft meets the charging handle area, no machining required.

The shaft of the bolt carrier on factory AKS-74us is reduced in diameter to better fit the 16mm hole. 

These do not fit milled spec 7.62 or 5.56 Krink kits, as the barrel journal is larger on those. They can be used with these kits if you turn down the barrel. However, if you're using a milled receiver, the ears of this block that sit inside the receiver are not as wide as a milled one would be.
7.62/5.56/Milled spec blocks are available from Kvar, but will need the ears narrowed to fit in a stamped front trunnion.

Version 2 blocks can be identified by now having a dimple guide for drilling the barrel cross pin, a feature version 1 was unfortunately lacking. 
Another upgrade present on Version 2 is the bolt carrier clearance cut mentioned above.

If you are using an AK-Builder barrel, you will have to modify your barrel or this block. AK-Builder makes their press fit diameter 17.65mm instead of the standard 17.52mm to accomodate oversized blocks from parts kits. If you do not correct this press fit, you run the risk of cracking the block, getting it stuck, or breaking something in your press setup.
The barrels sold on my website are already corrected.

Hardware is available here. A discount for purchasing the block and hardware will automatically apply in the cart.