Have you tried seed nicking to permit moisture to enter and initiate the germination process.

Yes, I have used sandpaper to thin the casing but I don't think I've made a nick.

How deep and whereabouts on the seed would you suggest?

Out of interest - what kind of seed is this?

I have used a nail clipper or modelling knife on hibiscus seeds to clip a small nick just so you can see the white embryonic tissue without damaging it looking at the seed I would try the rounded sides

Thanks, Steveg, I'll try that on a few of the seeds.

Ojibway93, it's Strychnos nux-vomica. I wouldn't expect anyone here to have grown it so I made the question general about large seeds.

when i germinated tree paeony i put them in a large diameter 'pan' and buried the pot in the border. chicken wire over the top to keep squirrels off. and left them alone. all 6 germinated. roots one yr and then shoots the next.

Have a look at this site if you have not already I think the germination percentage and the pre treatment of these seeds regarding part boiled water could be worth looking at
http://forest.ap.nic.in/silviculture%20of%20species/Forest%20Seeds/089.htm

Goodness, TPG, I hope you aren't planning on going into production with the plants - you could do some damage with those, despite what herbalists say. We shouldn't be surprised you are growing them, though, I suppose.
I usually use a scalpel blade or a penknife, and soak the seeds in cold water overnight to swell them - it seems to give them a head start.

Thanks all. I've tried the cowdung soaking in the past but not the hot water.

I see the thing about the roots growing fast. That was what foiled me in 2007 when I got 2 seeds to germinate but didn't pot on fast enough and the roots came out into the air under the pots.