Thoughts on the WiseLite made Goryunov SG-43
This is in no way meant to be a criticism or negative review of the WiseLite product.
At this point in time the WiseLite Goryunov SG-43 is no longer in production or offered for sale by them. I had one of their units in my shop for observation and a minor check up, so I decided to take photos of the mechanics and study it a bit. It's always educational to study other designs and how they approached design issues.
Their design is based on the use of a striker or sliding hammer system. This gave the obvious advantage of having a more original look to the gun. This came from not having the fire control box attached to the outside as my design does. It also offered other disadvantages of its own though.
The one modification that can be seen right off is the 2” addition to the length of the receiver. This was needed to house the striker and trigger sear system.
Here you can see the added section and the then needed side straps with button head screws used to hold on the spade grips.
The three arrows are pointing to plug welds used to hold in the blocking or denial bar required by the BATF to prevent insertion of the unmodified full auto bolt and carrier.
WiseLite chose to re-blue the receiver after the conversion. Unfortunately, welds seldom blue to the exact same color as the surrounding metal due to heat changes to the metal's structure.
Here's an interior view of the added receiver section. It looks like they made no attempt to weld the inside aspect of the joint.
This also shows the bilateral mounting straps used to hold the spade grips on. Please note that there is, from the original design, a very strong lug on top of the spade grip extension that locks into the top of the receiver. This absorbs a lot of the stress from recoiling parts hitting the grip unit.
Here's a shot of their spade grip unit with the forward tang extension. You can see the lug on the top which fits into the corresponding recess under the rear sight.
The extension also houses their trigger sear mechanism.
I thought that the whole trigger solution they came up with was creative and well thought out.
Here's the other side of the spade extension showing the sear. This locks into a square opening in the striker.
Here's the striker. This one part required a fair bit of time on the milling machine to make. The central opening is the slot that the sear locks into to hold the striker to the rear.
Here's the striker sitting on the spade extension showing the sear in the opening window.
The recoil spring group sits inside the striker and the long spring drives the bolt carrier and the shorter heavier one powers the striker.
Here's the recoil spring group arranged on the spring guide rod.
There were also several modifications done on the bolt and bolt carrier.
First off was a modification to the firing pin to allow it to pass fully through the bolt so the striker could hit it.
They also found a need to lighten the bolt carrier to increase its rearward velocity to make up for the additional mass of the striker and resistance of its spring.
This shows the bolt, bolt carrier, spring system and striker. Note the lightening holes in the carrier.
Their design, just like mine, had to have the bolt locking cam milled down to prevent full auto function.
Next I looked at the blocking bar setup. It is welded into the left side of the receiver and is made of a 1/4” by about 5” piece of square stock. The example I had didn't seem to have the blocking bar hardened at all and it appeared to be plug welded into the receiver. The AT told me that they would never approve such a system for my build. They may have gotten this approved and the ATF later upgraded their requirements for blocking.
The arrow points to the blocking bar.
It's highly exposed location would have also not passed the approval process I had to go through. I would think a few good hits with a hammer and punch would shear it right off!
Here's the corresponding denial slot in the bolt carrier. The bolt and striker also had a similar slot milled in them.
My system only has the slot in the carrier, but in a different location. I explained to the ATF that the bolt alone had no full auto features and therefore needed no denial system. And since I don't use a striker, a slot was irrelevant.
And finally, here is their butterfly trigger system. It works a bit like a double action revolver sear system. The spade shaped pawl presses against the round transfer rod and pushes it forward. About the time the transfer rod pushes the striker sear down, the pawl slips off the rod, releasing the striker sear. The spring and pivot pin setup allows the pawl to pop back up reset as the butterfly trigger is released.