Well howdy hey neighborino!
As a brewer and also a grower here in Colorado this was obviously one of the first things I've tried. I've been working on it for about 3 years trying to dial in the perfect weed beer.
Here's what I have so far:
I started like you did with tinctures and it does work very well. I was concerned about killing any yeast with the extra alcohol so I started with glycerin tinctures and even polypropylene glycol (the stuff they mix e cig juice with) and wasn't particularly blown away with the results. I made the switch to an alcohol tincture and found it really didn't have a noticeable effect on the yeast of my ABV. At first I started making the tinctures out of flowers, but since I also make BHO I started using it instead and found I got a much more potent and easier to work with product.
I typically will make my tinctures with everclear and will dose each beer in the bottling stage with an eye dropper and the equivalent of about 40mg of THC, which equals about .08 of decarboxylated hash oil.
What I love about my hash tincture is that I am able to tap into a much larger terpine profile than with my herbal tinctures. Beyond that, I've been blown away by some of the guys out there distilling terpines. I just picked up a few grams of distilled terpenes and added it to a beer and the results where INSANE. Like taking a massive hit off a joint with every swig and an aftertaste that had me licking my lips for days.
Few lessons to be learned from my mistakes:
If there is a way to keg this stuff, I haven't figured it out yet. I keep winding up with one hyper concentrated pint and the rest as a dud. Granted that pint is always one hell of a ride but not exactly what I'm looking for. No such problems in bottles and I haven't had any issues with bottle bombs like I feared when I started.
Also, your starting product is everything. Every time I see someone try to make weed beer they use some weed that they normally wouldn't smoke for one reason or another without realizing that they will taste every bit of it in the final product. I've had a lot of success with OG strains/ citra hops (funky as a mo fo) and also going the tropical route with mixing citra and a citrusy strain (citrix, lemon haze, etc). It's gonna sound crazy but try making a tea with your ground up herb before you brew. This will give you a good idea of the taste you'll get out of the final product.
Also, coconut oil will not work. Just trust me on this one. I still can't eat anything with coconut flavor without a dry heave or two
One neat idea I had for this winter: Take some decarboxylated hash oil and mix it into some chocolate you heat up in a pot. Pour it out and let it cool and then add it into the secondary like you would add chocolate to a 'regular' brew
Also in my quest for distilled flavors I've been messing around with distilled hop oil and if you go that route always remember that less is more. I've nuked my taste buds on more than one occasion
Hope that giant info dump was slightly interesting and I'm always glad to see someone else out there with the dream I've always had of getting high off a pint.
Mad scientists for life!!