In this video, I discuss the advantages and disadvantages of oval jump rings, especially with regard to welding chains.
Oval jump rings are preferred when you are not welding, because the seam naturally ends in the middle, so there is reduced risk of the items the jumping connects pulling through the seam. However, if someone is to weld the oval jump rings, there is no risk of the jump rings opening, but the seam weld mark will be visible.
A superior method would be to weld a round jump ring and then form it into an oval shape by pressing down, positioning the seam mark at one of the pointy ends of the oval. When the chain/connection is pulled, the weld mark will be hidden by the connecting items.
Click here for the full video.