I make dozens of jars of Olallieberry jams and jellies every year. Here's what I do . . .
First, I never cook the berries down as you would with apples or other pectin-loaded fruit. The flavor changes dramatically and always tastes a little metallic to me. This recipe is really simple and is basically the recipe found inside the Sure-Jell package (unless I add flavorings or mix in other fruit). Yields 6-8 half-pint jars.
5 cups smashed ripe BLACKBERRIES
1 box SURE-JELL FRUIT PECTIN
1/2 tsp UNSALTED BUTTER
pinch of SALT
juice and zest of 1 LEMON (optional)
5 cups GRANULATED SUGAR
Under no circumstances should you change the amounts of fruit, sugar or pectin. Also, don't try to double this. Like in baking, if you mess with the chemical balance, the end product will taste okay but it won't set-up the way you'd like.
So, once you've sterilized your jars, lids and seals (if that's your preference) mix the berries, Sure-Jell, salt, butter and optional lemon products in a 6 quart sauce pot. (Copper is the best kind of pan for this because of its even heating but I've used stainless-steel lined aluminum which works fine. Because of the acid in the berries, I wouldn't use uncoated aluminum pans)
Bring slowly to a boil, stirring frequently. Boil 1 minute, then add the sugar, stirring to mix thoroughly.
Bring this mixture back to a boil and when it's reached a "rolling" boil, (won't stop bubbling even when you stir it down) boil another couple of minutes and it's ready to be poured into jars.
If you want to remove some of the seeds (I usually don't) force the cooked mixture through a chinois or other large, fine-meshed metal strainer and process that. Know however, your yield will be considerably smaller.
Process as you prefer. I always do a water bath so the jars can be stored in a closet for at least a full year.
Good luck.