I purchased 3D printed parts for my Umarex Zelos including the baffles, forearm picatinny rail, and barrel band picatinny rail. While the filaments used are top quality and durable, the engineering is fundamentally flawed and presents serious safety risks.
**Forearm Picatinny Rail**
The forearm rail is friction fit only and rotates when using a bipod or vertical grip. Because it lacks a locking mechanism or set screws, any torque applied to the grip acts as a lever that unscrews the air cylinder at the regulator. This makes the rifle loose and unsafe while under pressure. All other similarly designed parts utilize a locking mechanism or jig that fits the anatomy of the rifle to prevent this.
**Barrel Band Picatinny Rail**
The barrel band is also a friction fit piece. It slides onto the air cylinder but does not come into contact with the barrel in any meaningful way. Without a way to pinch down or prevent rotation, it tweaks the alignment of both the barrel and the air cylinder. This creates divergent axes that are disruptive to harmonics and accuracy, and I believe it is a safety issue over the long term.
**Baffles**
The baffles performed well with the ammo I used and made a noticeable audible difference in the shroud. Installation was easy and they appear durable.
**Support Response**
After searching for nonexistent instructions, I contacted the seller. They eventually replied:
"Sorry for the late reply I was on vacation. There was a video until YouTube decided to take install videos down. It is a friction fit. If it is loose you can use silicon glue and that stuff comes right off metal but it holds well. I just wedge like a small plastic from a water bottle and that holds it in place pretty good."
Suggesting that a customer use a water bottle plastic shim to secure structural components on a high pressure air rifle is negligent engineering. I requested a refund twice and have yet to receive a response.
**Bottom Line**
Skilled printing cannot mask flawed engineering. I am now pursuing a credit card chargeback.
**Update**
I eventually purchased a forearm and barrel band from Evolve3D and have been pleased with the quality and functionality, while at a similar price point. There were zero safety concerns or installation challenges. I highly recommend Evolve3D for your Zelos accessories instead.
