4x20mm vs 3x23mm tritium vial brightness?

Geometry tells us that B@rt's 4x20mm tritium vials have 251 mm^2 of phosphor surface area and 251 mm^3 of volume. Merkava's 3x23mm vials have 217mm^2 of surface area and 163mm^3 of volume.

All things equal, B@rt's vials SHOULD be brighter, but are they really? By how much? I'm not counting the surface area of the ends, the dimensions don't account for the glass thickness, and the tritium pressure may be different, so the above numbers are just an approximation. If anyone has access to both of these vials, please do a side by side pic to show their relative brightness.

Thanks!

Bump for curious lack of response. I thought that both of these vials were pretty popular, but I guess not a lot of people have easy access to both.

I also am very interested in which is brighter. A side by side comparison would be great. there is also a large difference in price, so this would be good to know. Anyone?

I cant vouch for the merkava ones,(so not really helpful to the point of this thread ) but the b@rt ones are definitely bright, large step up from the 5.5mm or 8mm vials, from just working as a marker, to illuminating stuff around the vial a bit. I glued 4 blue ones in the bottom pocket of a glass bottle I converted into a change jar, and sealed them in with some GITD epoxy, and at night the bottom quarter of the jar is notably glowing from across the room, and not from the epoxy either.

This is an old thread but I posted some comparison shots of various tritium here on CPFMP.

I have to say b@rt and farid get the brightest vials.

Farid's vials are just as bright as b@rt's and a better price if you buy 3 but stock fluctuates.

B@rt's 18MM spheres are AWESOME and by far the brightest things. 16 TIMES MORE TRIT than 4x20mm vial. Much brighter than a 6" vial. Brighter even than my 20MM betalight torch

Merkava's are ALMOST as bright and are the best price and usually he stocks 8 colors.