Don't have any Hornby mk3 so cannot test. Do the items you own have NEM pockets fitted? Are these on camming mountings?
My GUESS : Whether or not on camming mounts, Hornby will probably have arranged their magnetic coupler with adequate clearance to allow the vehicles to negotiate the specified R2 minimum radius, 'plus some'; resulting in larger gaps between the gangway ends than necessary.
(This guess arises from their past practise with the Roco pattern clone 'close coupler' included with their Pullman cars and various other coaches. It's much longer than it needs to be: the shorter Roco original couples Hornby coaches with the gangways in contact on straight track, and opens out the spacing as required for curves, all the way down to R2 - which is how the system is meant to operate. The Hornby clone coupler doesn't go to waste, serendipitously it operates perfectly with the earlier release Bachmann mk1 coaches, which had the coupler pockets too far inboard to conform to the NEM standard. Every cloud has a silver lining and all that..)
Hunt couplers require an NEM pocket TTBOMK. If there is an NEM pocket, Hunt supply a trial pack of their product range. I'd go with that unless the maker can advise what's best for the particular vehicles you own, and the minimum curve radius on the layout.
My GUESS : Whether or not on camming mounts, Hornby will probably have arranged their magnetic coupler with adequate clearance to allow the vehicles to negotiate the specified R2 minimum radius, 'plus some'; resulting in larger gaps between the gangway ends than necessary.
(This guess arises from their past practise with the Roco pattern clone 'close coupler' included with their Pullman cars and various other coaches. It's much longer than it needs to be: the shorter Roco original couples Hornby coaches with the gangways in contact on straight track, and opens out the spacing as required for curves, all the way down to R2 - which is how the system is meant to operate. The Hornby clone coupler doesn't go to waste, serendipitously it operates perfectly with the earlier release Bachmann mk1 coaches, which had the coupler pockets too far inboard to conform to the NEM standard. Every cloud has a silver lining and all that..)
Hunt couplers require an NEM pocket TTBOMK. If there is an NEM pocket, Hunt supply a trial pack of their product range. I'd go with that unless the maker can advise what's best for the particular vehicles you own, and the minimum curve radius on the layout.
