Haven't myself (the stuff isn't easily available!), but there is a good article on the effects on conifers, particularly Cupressaceae:

Longman, K. A., Dick, J, & Page, C. N. (1982). Cone induction with gibberellin for taxonomic studies in Cupressaceae and Taxodiaceae. Biologia Plantarum 24: 195-201.

The results indicate that gibberellin injections stimulate marked cone production in many Cupressaceae (inc. 'Taxodiaceae') species, where by comparison, they had minimal effect on Pinaceae species.

Resin

^Interesting, I was able to find a few full papers in heavily scientific journals on google scholar.

Anyone else have any have thing else to share with Gibberellic Acid?

No knowledge on conifers. Know of success with foliar applications on ornamental trees to break a dormancy during growing season...15-20ppm inside greenhouse, 25-30ppm outside. I only know of a couple genus this is used on (Syringa,Betula). Will be working on a trial soon with Buxus to see if has similar effect.

Resin wrote:

"The results indicate that gibberellin injections stimulate marked cone production in many Cupressaceae (inc. 'Taxodiaceae') species, where by comparison, they had minimal effect on Pinaceae species."

This is generally true for Pinaceae but I believe I found a few exceptions that react with increased vegetative growth to concentrated GA3 foliar sprays:

Incredible results, Coniferophytus! What species have you here?
I did a literature search in 1989 and found that to that time gibberellin had been found in nature in Pinus just once: in pollen of knobcone pine, P. attenuata. I haven't kept up with newer lit.

1,2,3,4,5, 7,8 Japanese White Pine Pinus parviflora

6, 9 Scots Pine Pinus sylvestris

Resin

They are really just a few exceptions. As Resin pointed out, GA3 has generally minimal effect on conifers. I treated over 200 different conifer cultivars or wild forms (of 93 different species and 26 genera). Only the 3 plants shown had obvious signs of modified vegetative growth (however there is a whole lot of cones growing out there this year..) But the effect on vegetative growth seems to be cultivar-specific rather than 'species-specific'. Pinus parviflora Fukuzumi (shown in the pictures) reacted the most, 3 other Pinus parviflora cultivars showed no effect. Out of 5 different Scots Pine cultivars treated, only Pinus sylvestris Riverside Gem was affected (as shown in last picture). I am not too sure about the identity of the plant in pict 6. I do not think it is P. sylvestris - I will have to narrow down the different possibilities.