I would try inserting the tip of an exacto knife and try and depress the small pin. You need a very thin blade to catch the knob. Buy yourself the Briley cap and avoid all the hassle of the stock beretta cap.

 

Already have a Briley on order. Which side is the pin located? It's tightened down so tight I can't see any daylight there.

 

Its actually attached to the black ring that goes around the forearm near the vent. The pin is at 12 oclock if your looking down towards the forearm with the butt on the ground and trigger towards you. The little pin is NOT attached to the cap itself.

 

Finally got it. I started using machining gauges down to .003 and still couldn't get anything in there. Was able to do it with the tip of an exacto knife but I did gouge the hell out of it. Don't really care since I have a Briley one coming but that's a horrible design. I also ordered one of the spare red spacers from Brownell's.

Thanks

 

Use a small flashlight to look in the space between the cap and fore-end; you'll see it. A thin knife blade inserted into the recess will usually let you depress the pin and unscrew the cap. You may need to rotate the cap very slightly...clockwise or counter-clockwise to relieve the tension on the pin. When it is free, you should be able to depress it.

Please don't ask how I know this!

 

Glock you did good. Lots of people break the pin and damage the forearm. That factory cap is an over engineered piece of junk. Keep that Briley cap lubed on the inside especially the spring. The spring will rust.