Made by CZ, the Scorpion EVO 3 S1, is the civilian market version of a pretty slick 9mm submachinegun. Starting in 2015, the Scorpion was sold in the US as a pistol with a 7.72" barrel and no stock (thus the pistol designation). It's been a big seller for CZ and as you might imagine a very popular SBR candidate. Converting the pistol to SBR (short barreled rifle) requires that a number of Czech parts be replaced with US parts. This is for 922r compliance.
In 2016, CZ started importing two versions of the Scorpion in carbine form with a 16.2" barrel. One with a faux suppressor made by SilencerCo and the other with a muzzle brake.
The carbine version does not have the 922r compliance issues that the pistol does. Do the paperwork, pay the tax, and chop that barrel*, but please wait until you can do that legally.
If you're a lefty, you may appreciate the ambidextrous safety and a charging handle that can be switched left to right in about 10 seconds. However, there's no help with the ejection port or bolt release.
The red flat trigger and larger charging handle are aftermarket parts.
Pictured below, the lower magwell/trigger pack section removes with the push of a single captured pin.
The trigger group sits in a metal insert that is attached to the removable 'lower' by one 2mm hex screw, indicated with an arrow. This screw is made from some lousy pot metal, so have a replacement handy.
CZ is cranking Scorpions out at such a rate that the recent import versions have what they call a "World Legal" trigger pack. What makes it "World Legal" is a collar (removed here, but placement indicated by an arrow) on the inside of the trigger pack that's spot welded to the back of the 2mm hex screw. CZ does have a trigger pack exchange program in place, but if you don't want to wait, have fun
drilling the weld out like I did. Protip, buy the carbide tipped drill bit instead of being cheap like I was.The stock trigger was a sloppy 9lbs + on my Lyman gauge. After new springs and some conservative polishing, I've got it down into the 4/5 lbs range and the takeup's not terrible.
One part that most Scorpion owners remove is the safety on the trigger finger side (left or right). In the fire position, the safety digs into the trigger finger (last picture in this post shows that better than these do). Initially, I removed the right side safety and shaved it down as seen in the second picture. Wasn't a bad solution, and worked fine. However, I replaced it with this very nifty 'AK' style safety (the two lower pictures).
The 'AK' safety smartly uses leverage and is very easy to manipulate with my trigger finger, whereas the thumb side safety requires rotating the hand around the grip and a bit of force to engage/disengage.
Another upgrade was replacing the stock mag release with this paddle/Hk style release. I find it very intuitive to use. You can push to activate it with your index finger, just as you can with the stock release, but I prefer the grasp method for changing mags.
The bolt removes easily. Receiver interior shot shows the chamber and the charging handle rod.
The carbine and pistol version have two hook points for slings, but I prefer QD mounts. Added this back QD mount through an existing hook mounting point and the new handguard is MLOK so your mounting options are very flexible.
The grip is slightly adjustable and held on with one screw. Didn't think I'd like the stock grip, but it's actually comfortable if a little slick when you're sweaty. There are limited aftermarket grip options at the moment, but that will change. I'm waiting for something better.
I've topped this carbine with a Trijicon MRO red dot. So far, I'm a fan.
Other tidbits.
Criminally fun to shoot.
It's an easy platform to work on.
Comes with 2 20rd magazines and 30rd magazines are available sub $30.
There's no recoil of note when shooting.
I found it to be very accurate.
CZ does sell an enhanced trigger pack replacement. They also sell a number of parts directly from CZ.
There's a strong and growing aftermarket for this platform.
Negatives.
The ambidextrous safety is poorly designed.
Stock trigger is not great, but fixable.
Welded trigger packs, if you get one, are a hindrance, but again fixable if you're handy or willing to wait on an exchange with CZ.
Some of the screws and roll pins aren't made from the best materials. Easily replaced with better.
*New handguard and barrel removal. They're using the same system as the pistol, the problem is the carbine's longer handguard means we'll need a special tool to undo the barrel nut. I can explain that in better detail, but this is already way too long.
