Is 6 points problem?

[Foghorn]

I just brewed a Northern Brewer extract kit "Karls 90 Shilling 90". I was 6 points low on the OG (1.066 expected, read 1.060). I left it in the primary for 4 weeks due to other issues around the house. I am not sure why but I expected a 1.012 FG, can not find any FG's in the printed materials, but my other batches usually end up around that area. But I ended up with a 1.018, I am assumed that fermentation was over given the timeframe, so I went ahead and bottled. Will the extra sugar cause bottle bombs? And where would I find the expected FG for this particular recipe, I guess I could contact Northern Brewer!

 

[FreddyMar3]

I just brewed a Northern Brewer extract kit "Karls 90 Shilling 90". I was 6 points low on the OG (1.066 expected, read 1.060). I left it in the primary for 4 weeks due to other issues around the house. I am not sure why but I expected a 1.012 FG, can not find any FG's in the printed materials, but my other batches usually end up around that area. But I ended up with a 1.018, I am assumed that fermentation was over given the timeframe, so I went ahead and bottled. Will the extra sugar cause bottle bombs? And where would I find the expected FG for this particular recipe, I guess I could contact Northern Brewer!

Depends how particular you are, but I would say no cause for concern. As for the FG, check this out from BYO: "The 90-shilling ale of the 1800s, for example, had a final gravity of 1.055, while a modern-day 90-shilling has an FG of 1.020. "
https://byo.com/mead/item/718-great-scot

Sounds like you are right in range. don't worry about bottle bombs. Just make sure to calculate your priming sugar correctly and you'll be ok (AKA don't do a full 5oz packet if you don't have 5 full gallons). That .018 of gravity is most likely unfermentable sugars.