What did you think we were kidding when we said we were serious about precision shooting?

So we're big on precision here at STO, and this goes well beyond just lights. All of us shoot, and in the realm of shooting precision is also king. CZ, if you didn't know, isn't just one of the best values in firearms going, they're flat out just one of the best. In part, this is because they make their own cold hammer forged barrels last I checked. The result is an absolute tack driver of a system, but in this case let down by the factory stock. This gun started life as a CZ455 Suppressor Ready. The original American style stock was not well suited for precision shooting, both in its lack of consistency, and in its lack of adjustability for LOP and cheek weld. In the factory configuration, the gun hovered around or just over 1MOA factory at 100 yards. Some was the original stock, some was the little quirks/difficulties of shooting it like the original trigger.

CZ455 in a KRG chassis. With Lapua ammunition, the gun is effortlessly sub MOA.

A trigger job made delivering consistency easier, but really what the rifle needed was a proper chassis. Now here comes the disclaimer: everyone has their own preference for chassis systems. I personally prefer XLR Industries Evolution/Carbon over all the other options out there. Unfortunately, they didn't have a CZ455 inlet available, really there was just one option: Kinetic Research Group. Now I have the odd gripe about this chassis, but they do still have it where it counts: ACCURACY! After install, the gun went down to a consistent .5-.75MOA 5-10 round shooter at 100 yards. A real tack driver. Ever try to cold-bore an egg at >200 yards with no more than 10 shots on a .22? This gun makes people think it is easy... until they try it on their own rimfire.

The CZ455 Suppressor Ready with its factory stock and trigger. (optics and suppressor obviously not factory)

So KRG it was. One of the major gripes though, and the subject of this post, was the magazine well. You'd expect it to use its own magazine system or interface seamlessly with the stock CZ magwell. Instead there was a frigging monstrous hole in the bottom of the rifle. When you want to insert a new magazine you either have to fumble around like a virgin in the dark, bumping into all the wrong things in a desperate attempt to get it in, or flip the gun over to change mags. This is slow, annoying, inelegant, and if you bang the nose of the top round into something hard with a corner you just got a flier. This is a problem that needed solving, clearly.

KRG chassis magazine well as they expect you to use it from the factory. As you might imagine, achieving insertion with this setup is every virgin's nightmare.

Just about everything starts with an idea, progresses to a CAD model, goes through a few prototype iterations, and then reaches its final phase. Why should this be any different?

Prototype of our flared magazine well insert. The white ABS shows every rub, scuff, and apprentice mark necessary to get it to fit which, while ugly, makes design adjustments for the next round vastly easier.

We prototype with 3D prints all the time, this isn't news to anyone, but our reasoning for using white filament may be less obvious. You see, any time you're trying to fit something, there will be interference. Using white ABS means that, wherever something rubs, it becomes very obvious. Similar principal as to why you don't wear a nice white shirt in the shop. Turns out the front corners needed a little trim in order to fit. No problem.

The final part, seen here in 20% carbon fiber reinforced nylon. The nylon has excellent chemical resistance, while the carbon does technically increase rigidity however in this application it really is just for sex appeal since the part isn't partic… — The final part, seen here in 20% carbon fiber reinforced nylon. The nylon has excellent chemical resistance, while the carbon does technically increase rigidity however in this application it really is just for sex appeal since the part isn't particularly structural.

The corners tweaked, it was time to move to the final version. The issue becomes chemical resistance. ABS has somewhat poor chemical resistance, and firearms are notorious for having various aggressive chemicals used on them for cleaning and protecting. We went with 20% carbon fiber reinforced nylon, the nylon for its exceptional chemical resistance and the carbon fiber just because we can.

Magazine well installed. Much much better. Note the front action screw is still accessible, a deliberate design choice.

And there it is, all grown up, so proud. The results so far have been excellent. The part is actually half friction half mechanical fit, no adhesives or screws required, just a little coaxing with something flat and your hand or a small hammer to tap-tap-tap it into place. The rear hooks under the trigger guard and the front rotates down and wedges in place. Mag insertion is now effortless, simply justify the rear of the magazine against the real edge of the magwell, allow the flare to guild the magazine into place, and slide until it clicks.