I remember going to the hardware store to buy a piece of chain for securing my motorcycle. I got the biggest chain they had (and also the biggest padlock they had).
We measured out 6 feet or so and the clerk got his bolt cutters and whacked it in two. Well, I used the chain anyway.
You need better chain. I remember in the Navy we had to cut a chain and I had the bright idea to use a pair of bolt cutters. The chain was so hard that it put dents in the bolt cutters.