Well another update but this time to my second upper. I decided to ditch my earlier CQBR look ala navy seals and copy (somewhat) the Diemaco CQB rifle.
This was inspired by converting some Thermold mags.
A couple things of note are that I refinished the barrel away from that grey colour Systema uses to a gun blue/black colour. Much more like the Diemaco barrels.
Also is the ejection port door mod. I took this idea from another guy. It's a marui part that has a veneer of what looks like a bolt. I trimmed it and ground the receiver so it fits with the cylinder in place. I like the look.
On the front is a converted RS vortex flashhider
You can't really see it in these photos but there is a little Canada leaf on the mags that matches my C8 trades nicely.
The stock is wrong and I left the A1 grip on but those are easily changed.
I had to go with the A1 upper though as the Diemaco flat-top upper is too expensive to convert and the detachable carry handle is likely impossible to get.