HW99s imp / No Top Hat

[harvey_s]

If the piston bore clearance between that and the outside diameter of the spring has been taken up with a correctly sized sleeve - what good does a top hat do anyway?

[Garry]

I thought a top hat was there as a form of bearing for the end of the spring. That's the impression I have from what's inside my TX HC. It's the only rifle I've ever had, so probably wrong in that assumption.

[Phil Russell]

If the Imp is so good, why worry? It is perfectly normal to add a slip washer between the end of the spring and the bottom of the piston. A top hat can keep the spring central to the piston but if the fit is good anyway, most likely helped by a piston sleeve then it is dubious if a top hat will add anything extra .. but I have come across quite firmly fitted top hats that have a slip washer on them. Note that you don't want a top hat to be a very tight fit in the piston and a very tight fit in the spring such that it restricts the spring from 'unwinding' as it expands during a shot.
Cheers, Phil

[Shed tuner]

two main functions.

1) centralise spring in piston. May not be needed if the spring OD is a tight fit in the piston ID, but there has to be some slack to allow for compression, so it'll not be 100%
2) front brearing for spring to rotate against (with a slip washer)

also two secondary functions
3) secure piston sleave in place
4) ensure spring is seated squarely on the inside face of the piston

I really think every gun should have one.

[luckymjr]

Thanks for the replies and Info guys