Shires/Greenhoe F trigger “throw distance”?

[ericrich]

Hi all,

I have a .525 Shires with an original Greenhoe trigger. It plays wonderfully, however the throw distance is just a bit much for my thumb. Is there anyway to easily modify the throw so that the trigger engages without so much arc?

TIA,
Eric

[ithinknot]

Sure, think about leverage... assuming you're happy with the thumb rest position and want that to remain the same, you have two options.

- Overall lever length stays the same, and pivot point moves closer to your thumb. The pivot will currently be determined by the brace position, so this would require the fabrication of a (more) cantilevered mounting to be soldered to the brace AND either a new lever or at least a new pivot point on the existing lever. On the plus side, the overall lever length would remain constant, so the instrument would fit in your case exactly the same way.

- Thumb to pivot distance stays the same, and lever length on the rotor side increases. If there's enough play in the miniball linkage to accomodate a change of working angle, then this might be as simple as bending the vertical portion of the lever outwards (red line). Otherwise, you'll need a new lever made (blue line), which is also pretty straightforward shop work. Either way, this will mean the linkage sticks out further, and you'll have to check the case fitting. (There's almost certainly spare space either side in any normal case design, but it's something to consider before you slam the lid the first time...)

In any case, assuming consistent/optimal spring tension, the thumb travel will be reduced and the action will feel proportionately heavier because you're doing the same work over a shorter distance; the rotor has to move the same distance, so there's no free lunch.

[ericrich]

Thank you!