I had a batch of ginger beer OG 1072 FG 1027. (Crabbies by the way has a FG of 1033) I primed the bottles with a 1/3 tsp and everything was fine. The last bottles 2 months later were pretty fizzy though, not surprisingly. Now I've made another batch OG 1060 FG .995, had to sweeten it up with sugar syrup to about 1027 to make it taste like it should. There's no further fermentation but should I bother priming this time? I've been brewing for nearly 30 years so I know its not ideal to bottle with high gravity but will it still need priming. Logic says no, but I'd still like some opinions.
Even without additional sugar, I'd be worried about bottle bombs from sweetening by 30 points just before bottling. Actually, I'd consider it a near-certainty.
Crabbies probably has a post-fermentation FG of .99, not 1.033. Then they filter and pasteurize it to kill the yeast, and then they sweeten it.
For people doing bottle conditioning, there's a few ways to get sweet beers/ciders, in varying degrees of mad science. The easiest is to sweeten with a nonfermentable, like lactose or xylitol. A trickier way is to get the alcohol and sugar levels just right so that the yeast stop working at the same time they reach the appropriate carbonation level. (This can lead to strong solventy or hot-alcohol flavor.) The mad scientist-iest is to bottle sweet, wait for them to condition (prying off caps and recapping to check how far things have progressed), then boil the bottles to stop fermentation.
I'm a fan of the first method, because I find exploding glass frightening.