Hop-up chamber M249

The unique design, which is the result of a long development process, offers a combination of high performance and simple operation.

Precision CNC manufacturing and H+PTFE finish for the highest quality and durability.

Features:

• Designed for M249/MINIMI brands A&K, P&J, CA
• Fine adjustment of hop-up pressure - 360° control wheel range
• Marked hop-up control direction
• Perfectly tuned and long-developed shape of the internal collar collar for the hop-up rubber - successfully tested with most of the available hop-up rubber on the market
• Fitting design for AEG hop-up rubber bands with standard collar length (e.g. Systema), for use of hop-up rubber bands with longer collar lengths the supplied spacers can be used - more on the issue of hop-up rubber band collar length
• Define the clearance of the hop-up chamber in the mechabox opening using the included O-rings of two sizes
• Vertically seated hop-up rubber band pressure - also works great with Maple Leaf hop-up rubber bands
• Groove in the top of the hop-up chamber to allow for fixation in the outer barrel fit
• Ability to lock the chamber against rotation directly in the gun body, using the included worm.
• Replaceable pivot pin for axial locking of hop-up chamber in feeder - longer pin can be installed if required to ensure perfect seating.
• Made of aircraft duralumin EN AW 7075-T6 with H+PTFE coating
• Made in the Czech Republic

Package contents:

• Hop-up chamber
• Hop-up pressure control ring
• Hop-up pressure roller
• 2× locking O-ring (9×1.5)
• 2× O-ring for defining the clearance of the chamber in the mechabox bore (6×1 and 9×1)
• 2× collar collar hop-up rubber spacer (0.1 + 0.2 mm)
• 4× worm for fixing the barrel in the hop-up chamber (2× M3×5 + 2× M3×4 - they belong to the upper and lower holes in the groove)
• Worm for fixing the hop-up chamber in the gun body (M3×12)
• Longer pin for axial locking of the hop-up chamber in the feed shaft

Perfect fit for the collar of the hop-up rubber band

The shape of the internal fitting for the collar of the hop-up elastic band fundamentally influences the resulting smooth function and performance of the AEG gun. That's why we've dedicated the highest priority and dozens of hours of testing and adjustments to developing the most optimal geometry.

The result, however, is a versatile geometry solution that is compatible with the vast majority of hop-up rubbers available on the global market. Testing has been successfully conducted with over 30 types of hop-up rubber bands. The fitting is designed for trouble-free use and good sealing of AEG hop-up rubber bands with standard length collars. If using a hop-up elastic with a longer collar, the supplied spacers can be used.

Great emphasis is also placed on the quality of manufacture and surface finish of not only this essential internal part of each hop-up chamber.

Innovative fit of the chamber

The second factor that fundamentally affects the performance and function of the AEG gun is the fit of the hop-up chamber in the outer barrel and mechabox. A hop-up chamber that is off the cylinder head - nozzle - chamber - barrel axis causes performance drops and feeding or even choking problems.
The supplied O-rings of various sizes can be used to define the clearance of the hop-up chamber in the mechabox bore, and therefore the seating in the axis.

For accurate shooting and smooth feeding, it is essential that the chamber is not allowed to rotate on its axis. The chamber is fixed against rotation in its axis by a groove in the feed shaft of the gun as standard. This groove accommodates a pin from the bottom of the chamber, which can be replaced with a longer one if necessary (if it is too short and does not fit into the groove). The longer pin is included in the package and can replace the basic one. The latter needs to be heated with a heat gun for replacement.

An alternative way of fixing the chamber against rotation is to use the thread at the top of the chamber near the hop-up control ring. It is then possible to fix the chamber in the groove of the centre part of the gun body using the supplied M3×12 worm. This option is particularly suitable when the possibility of quick removal of the outer barrel is not used. If you want to remove the barrel using the quick-change mechanism when using this method of fixing the chamber, the fixing worm must always be unscrewed first.

A third option (for example, for access to the battery in the fore-end) is to use the groove in the top of the chamber to fix the chamber directly in the receiver fitting part of the outer barrel. Although a modification of the fitting is necessary, the modification allows the chamber to be fixed against rotation while maintaining axial movement in the direction of the pressure spring on the mechabox. This preserves the original function of quick removal of the outer barrel - this movement of the chamber is needed when locking the outer barrel into the gun body. Translated with www.DeepL.com/Translator (free version)