I picked up a used A3 collapsible stock for my Zenith Z-5RS and had a question.

Although it fits just fine and functioned great when I was playing with it around the house I final got a chance to take it to the range today and I ran into a recurring issue.    The stock would extend with no issues but after shooting a few mags when I went to collapse it to let the gun cool off and I couldn't get the dern thing to budge.   Ultimately I had to pop the pin and pull off the stock then it seemed to start working again just fine.  The same thing happened to me again later.

For the record - yes, I have SBR paperwork and yes, I changed out the buffer on the stock before I installed it.

Any ideas?

I thought about taking the stock apart and doing a thorough cleaning but I can't find a good video demonstration and the written instructions I found were pretty vague.

Thanks for your help.

I can't help you with the issue you have but, do not take the stock apart. You need a special tool to twist the spring in the stock and put the lever under pressure. I have two A3 stocks and took one apart. After I could not get the spring under pressure I found out about the tool. I spoke to a former PD armor I know and he told me that when he went through MP5 armor school, HK stated to never take the stock apart. I am now looking for a way to put it back together properly.

OK, that is GREAT info to have.   Thanks Rookie.

I cleaned the beejesus out of the stock today with everything at my disposal including Hoppes, brake cleaner, cleaning patches and q-tips, ended up getting a lot of gunk out of it.   Hopefully this fixes the issue.

Plastic release paddle or metal? The metal one can be taken apart and there is a tab on the button to "preload" the tension spring. The plastic paddle one doesn't have the same design and I wouldn't take it apart.

It is metal.

But now I am back to my original question.

It is metal.

But now I am back to my original question.

Try this before disassembling anything-

Push the little dogleg piece into the ratchet cuts and hold it in, and rotate the stock release lever while doing so. This will tighten it up. See if that fixes the release and collapsing. If not, then follow this for disassembly

That is a great tip, Thanks!

Between this and the can of break cleaner I put through the stock it is behaving much better now.   Still a little finicky but I am starting to think that is just the nature of these stocks.