10. 03. 2025
Our good old RetroArms hop Up chamber for AR15s with recently finetuned main shaft and feeding shaft drilling.
The chamber is machined on a precise CNC machine from aviation-grade aluminium EN AW 7075, is anodized and even though the chamber doesn't have any extra adjustable features such as feeding regulator etc., it is already R-hop ready and it's a powerful upgrade part machined with tight tolerances.
On a feeding shaft, you can find an o-ring, which prevents unfired BBs from falling out when reloading.
Another feature is a collet nut instead of a centering ring in the front of the chamber. When the collet nut is tightened, it holds the inner barrel and the chamber centeredand tightly together and thus mitigating any movement of the barrel. Just make sure that you do not let the barrel rotate in the chamber when you tighten the nut. Another advantage of this nut is that it can hold barrels with different outer diameters (typically 8.4 - 8.5 mm).
Recent fine tuning of the main shaft and feeding shaft ensures compatibility with most HopUp rubbers and improves feeding reliability and consistency of the chamber.
Hop Up Chamber BASIC is designed for players, who want a 100% reliable and precise Hop Up chamber that just works without necessity to tune anything.
This Hop Up chamber is a slightly redesigned version of Hop Up chamber BASIC. It is machined on a precise CNC machine from aviation-grade duralumin EN AW 7075 and anodized. This Hop Up chamber is R-hop ready and is meant to be used in setups, which have troubles with magazine installation in the body, which are not unlocking and feeding.
The feeding shaft screwed in without any shims sits in the same position as the shaft of the BASIC Hop Up Chamber. The height of the feeding shaft can be adjusted by 0.2 mm increments with included shims. After assembly and tuning we recommend securing the adjustable feeding shaft with medium strength thread glue.
On a feeding shaft, you can find an o-ring, which prevents those 4 BBs from falling out when reloading.
Another feature is a collet nut instead of a centering ring in the front of the chamber. When the collet nut is tightened, it holds the inner barrel and the chamber tightly together and thus mitigating any movement of the barrel. Just make sure that you do not let the barrel rotate in the chamber when you tighten the nut. Another advantage of this nut is that it can hold barrels with different outer diameters (typically 8.4 - 8.5 mm).
Recent fine tuning of the main shaft and feeding shaft ensures compatibility with most HopUp rubbers and improves feeding reliability and consistency of the chamber.
The adjustable feeding shaft part is identical with the one on the ULTRA version.
The ultimate solution for players, who want a fully customizable Hop Up chamber.
Hop Up chamber ULTRA is also based on our chamber BASIC and is also made on precise CNC machines from aviation grade aluminium 7075. This chamber also has the adjustable feeding shaft as the chamber PRO.
New features include adjustable nozzle shaft, which is meant to be used to make the chamber sit more forward, when necessary. This feature is really helpful for tuning the longitudinal position of the chamber and thus e.g. adjusting the reliability of feeding, or position relative to the magazine. The position can be adjusted by 0.2 mm increments with included shims. Bear in mind that this feature also requires use of different length nozzles. The adjustable nozzle shaft will be offered with multiple outer diameters for you to choose the best option according to your GB shell.
The next ULTRA feature is the inner barrel securing mechanism. Compared to the standard solution, we completely redesigned this mechanism, to mitigate the main fault - the C-clip cannot hold the barrel in place (longitudinal movement and rotation).
This new system consists of a reshaped C-clip made of POM, and a custom union nut, which holds the C-clip tightly to the barrel and is also precisely machined to be able to reliably center the inner barrel. With this solution, the C-clip cannot twist loose with barrel rotation and the barrel cannot move longitudinally, because it is tightened with the union nut. Tighten the nut only by hand! The union nut has a maximal outer diameter of 12.95 mm, which should fit into the majority of outer barrels, but make sure it can fit before purchase.
Another difference is the main shaft shape in the ULTRA chamber. Compared to chambers BASIC and PRO, the shape of the drilling is adjusted in the area where the Hop Up rubber sits. It is made flat and standard AEG rubbers are meant to be used with included rings. Those rings fill in the material, which is missing and can be adjusted e.g. by sanding to compensate for different hop up rubbers dimensions. Another reason for this drilling is to allow use of our new ROBUST hop up rubber.
Hop Up rubber ROBUST is a standard rubber, but with flat nose, which brings two main advantages:
