I have a five-pound electronic postal scale and it's only accurate to 1/8 ounce (about 55 gr). This is most definitely
not an acceptable margin of error for sub-scale artillery charges. I use it for its intended purpose, shipping, and occasionally in the kitchen to weigh out meat or seafood. It's no powder scale to be sure.
The prices on decent electronic bullet/powder scales have dropped drastically over the past few years, to the point that it's hard to justify
not having one.
Get one. I don't really like the 'pocket' scales but that's just a matter of personal preference.
This is the one I use:
Good scale, bad photo. This one has a 1500 grain capacity, and will also read in grams, ounces, etc.
You can buy a similar one now for considerably less than I paid for this one years ago.
Once you have it, you'll wonder how you ever lived without it.