MidwayUSA Everything I looked at had a 3 box limit.  https://www.midwayusa.com/shotgun-ammunition/br?cid=9217&targetLocation=%2F_%2FN-9217%2B4294957290%3FNp%3D2%26Nr%3DAND%28p_visible%3A1%2Ccustomertypeid%3A1%29%26Nrpp%3D24%26Ns%3Dp_metric_sales_velocity%7C1%26Ntpc%3D1%26Ntpr%3D1