And yeah, no active spore is going to live in there and produce co2 for 6 mos.
You might be able to shut 1 up in a 10x10x10 air tight shed for 6 mos and there be 2000ppm of co2 in there 6mos later, but that's even doubtful...
This big bag bomb would release all its Co2 within two or three weeks, month at the very very max.
If it looks to good to be true, and seems to good to be true, and comes from montana, smack the bastard.