Well Mb03 bolt not catching!

[Philhooper2024]

I recently upgraded my Well mb03 with a upgraded piston and spring 90 degree 

I also purchased a 90 degree trigger box with the seats that are correct for the piston, now I installed it and after putting it together I pull the bolt back and it doesn’t catch it just springs back forward. It doesn’t slam fire!! So that’s been ruled out. I have noticed that when I undo the trigger guard and take that off it works fine but that’s obviously an issue as it’s all ment to go back together and it seems the only way to have this working would be without the trigger guard. Any ideas on what is causing the problem and how to fix it would be appreciated. 

[The_Lord_Poncho]

It's a different platform admittedly, but on my MB01 when I added in a new piston, I also had the same problem as you describe. My problem was that the piston wasn't quite able to move back far enough in the cylinder for the sear in the trigger unit to pop up and then catch and hold the corresponding ridge around the piston. It was a few years back, but from memory, it was very easily solved in my case by using a metal file to remove a few MM thickness of metal off the rear of the piston so that it could move further backwards in the cylinder.

[Philhooper2024]

So if I just filed a bit of the piston sear this should hopefully solve the problem? Could u provide a picture or a diagram for the part I would need to file? 

[Philhooper2024]

6 hours ago, The_Lord_Poncho said:

It's a different platform admittedly, but on my MB01 when I added in a new piston, I also had the same problem as you describe. My problem was that the piston wasn't quite able to move back far enough in the cylinder for the sear in the trigger unit to pop up and then catch and hold the corresponding ridge around the piston. It was a few years back, but from memory, it was very easily solved in my case by using a metal file to remove a few MM thickness of metal off the rear of the piston so that it could move further backwards in the cylinder.

Makes sense to me, could you post a pic or diagram of the part you filed so I don’t cock it up totally! 😂

[The_Lord_Poncho]

Sorry, i'm not going to have time to give you anything comprehensive - but it is the rear of the piston that i filed off, not the sear itself (which could weaken it). Just a few mm was enough for me. But note that it may be a different cause in your case - it would be interesting to compare the length of your original piston with the replacement one first.

[Philhooper2024]

58 minutes ago, The_Lord_Poncho said:

Sorry, i'm not going to have time to give you anything comprehensive - but it is the rear of the piston that i filed off, not the sear itself (which could weaken it). Just a few mm was enough for me. But note that it may be a different cause in your case - it would be interesting to compare the length of your original piston with the replacement one first.

I solved the problem, the piston that I brought as an action army 90 degree piston with a m160 doing, now what I noticed was the rear of the piston was short and there for unable to catch, so I’ve brought a 90 degree piston that has a longer rear and hoping this solves the problem as a friend of mine had the same issues as i. But just for the sake of it I’m going to file a this bit down and see if it makes any difference to test it.