Can a Mr. Beer fermenter handle 2.5 gallons?

I was curious because I have one of these around that I was hoping to use since I do half batches. The fermenter is designed to hold 8.5 quarts (a little over 2 gallons), but I have read that it can hold 2.5 gallons. However, I haven't found much of any testimonials regarding the results of putting that much wort in it. Would there still be enough space for the fermentation? Would it go crazy and start flowing from the lid?

Has anyone tried 2.5 gallon batch in a Mr. Beer fermenter? I just want some reassurance before going ahead with the brew. Thanks.

The two times I've tried to jam that much in there it almost exploded. Actually, the first time it just blew out the vents. The second time it was seething and fizzing and seeping the wrong way out the valve on the spigot, and the top was bulging. It blew crap all over when I took the top off.

Many people on the Mr. Beer thread will argue it can handle it, but I'll never fill it that high again without drilling the top and installing a blow-off tube. Bear in mind that it just has little tiny cuts at the top of the threaded part where the cap fits to allow CO2 to escape. If anything at all clogs those, like krausen or hop debris, you have a very large bottle bomb on your hands. IMHO it's not worth it for less than a couple of quarts. If you want a bigger batch get a bucket. They're cheap and work great. Use the Mr. Beer Little Brown Keg for the batch size it was designed for. It's still a pretty reasonable amount of beer.

Keep in mind you can always brew your 2.5 recipe with just 2 gallons, ferment it, then boil your priming sugar in .5 gal of water when you bottle.

The most I put in my MBKs is 8.5 liters (2.25 gal) of a sub 1.055 OG wort fermented by a moderately fast yeast. If I am using a fairly quick, aggressive yeast or a higher starting gravity, 2 gallons is the max.