[Question] Is there a height requirement for launch tubes for launching 8 inch canister shells?

I bought 8inch HCMF Cobras and want to launch them in volleys. Maybe all 24 in one sequence. However, I do not have enough tubes and could light them in volleys of 12.

I have HDPE tubes from previously owned canisters but they are 3 inches shorter than the tubes the HCMF came in. Is it okay and safe to launch these canisters from these tubes?