VSR - bolt won't slide forward

Heeeelp!

Fitted a new set of steel sears to my TM VSR and the bolt will pull back and 'cock' the gun but jams and won't slide back in. The kit I fitted is here: http://www.actionhobbies.co.uk/Steel-Tr ... AQQY5.aspx

What have I done wrong? If I loosen the screws holding the trigger assembly slightly, the bolt will then shoot forward. The only thing that I can see is tho at the < shaped sear (springy one at the front) doesn't go back flush into the main trigger sear?

I don't think it should go back flush. At that point it should be holding the piston in place, shouldn't it?

If you take it out can you move the piston with your finger through the slot? i.e. is it stuck?

The bolt moves freely when the trigger unit is detached.

I think that the bolt is catching on the piston sear as the black paint seem to be slightly rubbed off (at the top) but I've no idea why... The piston is a std Laylax PSS10 and it's a 150 spring.

Any idea what I done wrong or what's FUBAR'd in the main gun, if the sears are okay?

** EDIT - is it possible to fit the trigger mech back on when the sears are not aligned correctly? That's all I can think off TBH? **

Have you fitted the bolt in after the trigger mech has been attached, or before?

When I do this sort of thing I usually slide the bolt in last and then put the spring guide stopper in. As you slide the bolt in, push the piston sear down with a long screwdriver so the bolt can get over it.

When operating, the piston sear should lock on the piston and I think if it's locking on the front of the bolt then the bolt is being pulled too far back?

If all else fails... take it all apart and try again...

So I went and reversed out all the changes...

I've taken the trigger mech apart and put the original TM trigger sear back in with a steel laylax piston sear and now the bolt slides in and out (good) but the damn thing won't cock!

Pulling the bolt back, I can feel the spring compress but then the bolt doesn't catch - just flies forward.

What the <fruit> has gone wrong now?!

Thanks for the info, Tom...

<sigh> It's an upgraded piston AND piston sear... can't see any sign of wear but I am losing the will to fix this gun so I think I will re-fit the stock piston, sear and spring and get rid of a what will be a fully working 330fps VSR and a box of upgrade parts.

have you upgraded the trigger sear becuase if not this will be why as generally this is the first to break out of the two sears as it bows under the pressure