broccoli_pug Posted September 14, 2022 Share Posted September 14, 2022 I recently acquired a Promag M4 collapsing stock and it seems like the retaining pin is a common point of failure on these. I have seen other posts here mention replacing the pin but I am unsure how to access the pin. Has anyone done this before? Pictures or parts guides would be greatly appreciated. Quote Link to comment Share on other sites More sharing options...
StrangerDanger Posted September 20, 2022 Share Posted September 20, 2022 I've never done it before, but I have read that the OEM collapsible parts fit the Promag stock. So you'll need to source those parts from a place like Numrich Arms. https://www.gunpartscorp.com/gun-manufacturer/benelli/shotguns-benelli/semi-auto-shotguns/m4-super-90 I guess I'd replace: 114 - Retaining Pin 116 - Button You can remove 114 by removing the plastic cheek comb via the three screws on the top. This will allow you to drive the 114 retaining pin out from the bottom of the stock. There may be some staking at the top of the stock to push thru, but it doesn't really matter and it is easily driven out. I would then replace the button. The Benelli button is the hardest steel I have ever seen. To remove it, you'll want to depress the button slightly while driving the roll pin out from the front of the stock rearward. If it is like the oem setup, there will be a greasy spring beneath the button. Put the spring on the new button and depress it into the stock while hammering the roll pin back into place from the front of the stock to the rear. You want to depress the button slightly while you hammer it in to prevent any chance of damaging the spring with the roll pin. So it is kind of a three hand job. You'll want to have the stock on a bench so one hand can stabilize it, and press the button in with your middle and ring finger while holding the roll pin at the same time between your thumb and pointer finger. Then hammer with the other hand. Then reinstall the cheek comb. Quote Link to comment Share on other sites More sharing options...
benelliwerkes Posted September 20, 2022 Share Posted September 20, 2022 I am not sure I understand the OP question. However, the grip retaining pin is secured by asymmetric apertures on either end of the pin. It can only be removed one way! which is left to right. These might help. Quote Link to comment Share on other sites More sharing options...
StrangerDanger Posted September 21, 2022 Share Posted September 21, 2022 I think his goal is to replace the two parts I listed since the Promag version comes with Chinesium grade components that don't hold up. Quote Link to comment Share on other sites More sharing options...
benelliwerkes Posted September 21, 2022 Share Posted September 21, 2022 ^^Aha. Got it. Quote Link to comment Share on other sites More sharing options...
broccoli_pug Posted September 22, 2022 Author Share Posted September 22, 2022 Yes StrangerDanger is correct, I am hoping to replace some of the internal components of the collapsing stock. Right now there is some side to side wobble that I am not satisfied with. I am going to try replacing the retaining pin first and then the button if it comes to that. Thank you both for the pictures and instructions! Quote Link to comment Share on other sites More sharing options...
StrangerDanger Posted September 22, 2022 Share Posted September 22, 2022 Even the OEM collapsible stocks will have a little bit of wobble. Some are better than others. Quote Link to comment Share on other sites More sharing options...
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