| CPC E21B 43/119 (2013.01) [E21B 43/117 (2013.01); F42B 3/02 (2013.01); F42B 3/103 (2013.01)] | 20 Claims |

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1. A method for using a tandem sub for connecting one or more perforating gun assemblies, comprising:
providing a tandem sub with a first rotational mechanism at a first end, and a second rotational mechanism at a second end,
coupling the first end to a first perforating gun with a first charge tube, wherein the first rotational mechanism engages the first charge tube in a first perforating gun allowing the first charge tube to rotate freely;
coupling the second end to a second perforating gun with a second charge tube, wherein the second rotational mechanism engages with a second charge tube in a second perforating gun allowing the second charge tube to rotate freely.
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