I am running the dellorto 13.13 and a modified tecno estoril, also ran a fixed polini long country with it before.
Yeah, I packed them all with lead, and weighed each one, then sealed and fine tuned the weight with nail polish so they are all the same weight.
If you don't have a scale; they were less than half a gram off with the same number of pellets in each, maybe .2-.3, I don't think that would mess anything up, or even be too out of balance unless you put all the lightest ones on one side and all the heaviest on the other by chance.
Some people mix and match weights, like with the polini, three and three, two and four, as long as you distribute them evenly it's fine, some people even use three out of five or even two out of three in various stock variators where you need less weight.
You can probably get a digital scale at your local convenience/smoke/head shop for pretty cheap, or just count the pellets and pack the same number in each. You don't really need to be careful and do it in steps like I did, a gram (about two .177 cal) at a time, and try it, it gets tedious, and you can't really tell much difference, and i found you can't make them too heavy, so just pack them to the max, and you can always drill some lead out if you ever need to later.
But do try them first before you pack them, you got to experience that peeling out the driveway mad rush to 25 at least once!