MSR bolt catch issue

My MSR bolt isn’t catching properly, just started happening randomly last night. I draw it all the way back, and instead of being able to push it back forward and pull the trigger, it releases the spring as I push the bolt back forward. I pulled it apart and put it back together, wasn’t able to determine the issue, any ideas?

Probably the nylon tab on the piston wearing out from contact with the metal sear.

It’s an issue that many have anticipated and some are hoping to avoid by fitting the metal barrel upgrade kit.

Update
I sanded and coated the tab in a layer of superglue but expect to have to cover it with a steel plate or bolt a nut to it someday.

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Where would be the best place to get the metal upgrade kit?

Look in ebay. ~$150

If it’s like the SSG 69 there is a small hump at end of piston that the trigger mechanism catches, it wears down pretty quick. I filed it back a bit and it’s working again, for how long I don’t know

A couple chaps have used metal to resurface the contact points successfully

What do u mean by resurface, something like knead it ?

Can’t remember who it was used a flat S hook

Id planned on using flat stainless strip and forming it but S hook ia damn near the right shape ootb

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There is also enough material there (~5x5x3mm) to work with.

What about wrapping a shim around it and gluing in place?


The nylon stock piston has a tab that engages the sear.
It fits through the slot in the cylinder.
This is the part I sanded down and covered with superglue gel. You can wrap something over the top and bottom or drill a tiny hole and put a bolt through it, using the head as the contact with the sear.

Can’t wrap anything around it as it is a snug fit in the slot.

The metal kit appears to do away with this, replacing it with a flange instead. That means the piston can freely rotate and engage the sear at a different point each time.
That will certainly make it last a whole lot longer. It does mean the sear now reaches into the cylinder to latch on. Not sure how the change in angle affects the rest of the levers or trigger angle and play but it obviously works.

Better design. :+1:

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Anyone know what sized spring I can put in with the stainless steel kit? I’m currently averaging 347 fps and would like to keep that.

Any particular size? Just one from Bunnings? And it just goes over the connection point on the cylinder?

Any chance you have a link or image of this?

search here.

it was a board member who provided pics etm.

i think it was a bunnings S hook