I have begun to get into all grain batches for my brewing. Since I am only just beginning and live in an apartment I've been using a mixture of Deathbrewer's Stove-Top method and Charlie Papazin's bucket lauter tun (it may not be his, but that's where I saw it first).
I've done 2 batches and both have turned out great with the following procedure:
1) Heat strike water to desired temp
2) Measure out grain into 5gal paint bucket net strainer (big bag)
3) Take water off stove put grain and bag in pot and put lid on
4) Put pot in oven (oven is off) for 1hr, stirring every 15min or so
5) Place bag of grains in 5gal bucket with holes in the bottom which is inside another 5gal bucket with a spigot
6) I then cycle the wort through the grain until it begins to run off clear(ish) while beginning to heat my sparge water
7) Using the sparge water I top off my brewing pot to the desired amount of boil water
Now, I am planning a brew that will exceed the limitations of my 6gal pot or at least come too close for my comfort. Rather than get a bigger pot or dedicated cooler I'm curious to know if I could just use a regular cooler (that I use for other things - i.e. can't be converted into a MLT) for the mash then pull the grain bag out and then pick up at my bucket lautering steps. I realize that not all the grain and mash water will fit in the buckets, but after cycling the initial bit of water that fits, I can add some more mash water and cycle and so on until I've hit my boil volume.
For specifics, it's a strong scotch ale with a 15lb grain bill - so I calculated 3.75-5gal of sparge water.
Any and all help will be appreciated! Thanks!