I encountered a new problem with a blowback pistol today. I was testing out a used long-barrel Gomo PT-25 that I bought. Since Gamo no longer sells parts I am starting to think that it is cheaper just to purchase a used (or even new) gun and cannibalize it for parts.
Anyway I noticed that one chamber of the dual-magazines was failing to advance when I pulled the trigger. I could only fire seven shots of the eight in the mag.
This was my first opportunity to crack open a Gamo pistol mag. It has four screws, two at each end. Once opened both magazine wheels fell out because they are spring-loaded. I carefully examined both wheels. Most of the chambers had worrisome scratches on their surface. These could cause air leaks. The mag body had a few dings too.
Each chamber of a mag wheel has its own tiny indexing detents below the chamber. If one broke off or got worn down then there would be nothing to contact to index the wheel's chambers.
Each tiny detent is beveled on its leading edge. This is why the wheels should only be rotated clockwise when loading the mag. Turning counter-clockwise will cause the wheel lock pin to strike against the hard edge of the detent instead of over its beveled edge.
None of these things were causing the wheel advance problem.
All that was left was the spring-loaded buttons that tension the wheels against the mag housing. This was the problem - one of the buttons had a piece of its plastic was scored so that the round button could not fit straight down into its retaining hole.
I used my dremel tool to sand off the offending burr. Problem solved!
Anyway I noticed that one chamber of the dual-magazines was failing to advance when I pulled the trigger. I could only fire seven shots of the eight in the mag.
This was my first opportunity to crack open a Gamo pistol mag. It has four screws, two at each end. Once opened both magazine wheels fell out because they are spring-loaded. I carefully examined both wheels. Most of the chambers had worrisome scratches on their surface. These could cause air leaks. The mag body had a few dings too.
Each chamber of a mag wheel has its own tiny indexing detents below the chamber. If one broke off or got worn down then there would be nothing to contact to index the wheel's chambers.
Each tiny detent is beveled on its leading edge. This is why the wheels should only be rotated clockwise when loading the mag. Turning counter-clockwise will cause the wheel lock pin to strike against the hard edge of the detent instead of over its beveled edge.
None of these things were causing the wheel advance problem.
All that was left was the spring-loaded buttons that tension the wheels against the mag housing. This was the problem - one of the buttons had a piece of its plastic was scored so that the round button could not fit straight down into its retaining hole.
I used my dremel tool to sand off the offending burr. Problem solved!
