WEll, my next attempt at BIAB will be next week. I have NB's Dead Ringer on hand. It's supposed to yield 3 gallons of 1.064 wort. They say to start with 5.5 gallons of water. Last time I did this, with their suggested 60-minute boil, I ended with 4.25 gallons of 1.042 wort. So, this time I will try a few things per all of your welcome suggestions:
1. Be sure to watch my mash temp and make it as close to 152 as possible as I might have been a little warm last time.
2. Mash for 90 minutes
3. Squeeze the bag before letting it drip into the brew kettle
4. Do a dunk sparge with 165 degree water.
5. Squeeze the bag again
If this doesn't result in a better efficiency, I won't know what else to do...
Might I suggest only changing one variable at a time? Otherwise how will you know what fixed the problem?
Personally, I don't think your mash time is the culprit. If it isn't then you just added more time to your brew day for no benefit.
And just so you know, last time you made Dead Ringer, if you would have kept boiling that 4.25 gallons of 1.042 wort down to 3 gallons you would have hit a 1.060 OG. Pretty stinking close to the 1.064 you were going for. Since you ended up with more volume than you wanted it sounds to me like your boil off rate number is askew or your started your boil with a higher volume than you should have.
This is exactly why you should take multiple gravity and volume readings all along the process of brewing. If you see you have more volume than you wanted, but your gravity is spot on for said volume, then you can just boil longer to get rid of the excess water and adjust your hop additions to coincide with the new schedule.
I've found that brewing sometimes requires being able to adjust when things don't go as planned. Taking these readings will help you do that.