Kral Bullpup Rear adjusting cap in Aluminium/Stainless Steel with larger diameter spring guide. This is to replace the standard one.

The standard cap has an anti tamper cap with a plug that goes into the bottom, this has to be removed before fitting our one. I have them in stock now.
You need to remove the adjuster at the back to gain access to the hammer spring. The hammer spring on these guns will resonate making a ringing noise when the gun is fired. This is more noticeable if you fit a good silencer.