I had gotten behind on my brew schedule and decided to catch up by bottling three 5 gallon batches yesterday. The bottling and everything went fine, thanks to the tips on the forum.
I have heard that some extract brewers don't bother with hydro readings, because there's no mashing/lautering or efficiency to worry about. So, I figured after 5 weeks in primary my Porter would be ready to bottle. I just went ahead and bottled it all.
When it was all said and done I had about a third of a bottle left. I decided why not check the FG to calculate the ABV. The FG was 1.028, well above what it should be (OG 1.63). I don't know why the gravity was so high, but I am rather angry with myself that I made two cases of bottle bombs.
Fermentation temps were on the lower end of the range for the first three weeks; then I moved the primary to 70F ambient for the final two weeks.
Now the cases are wrapped in towels sitting in the basement waiting for the inevitable, but hoping not all of them burst.
Lesson learned. Get a thief and ALWAYS check gravity.