Increment cores with intact tree rings are crucial in dendrochronological investigations to age trees. However, it is not always possible to obtain complete cores from trees because of rot, so alternative methods need to be explored. We tested the collection of one oblique core and one straight core reaching the pith at breast height from 12 sound Scots pine (Pinus sylvestris) trees. We simulated a missing inner part (caused by hypothetical rot) from each straight core, and estimated the trees' ages from both the oblique and straight cores, using several methods. We then compared the estimates to ages obtained from the complete cores, and found that the mean absolute error was lower for estimates from partial straight cores (17.75%) than from oblique cores (47.58%). We then obtained oblique cores from 14 hollow pines affected by rot, to test the applicability of this practice to real rotten trees. We concluded that oblique coring is not suitable for pine trees because of high failure rates of coring attempts and large distances between the cores and chronological centers of the trees' stems. We recommend the collection of two cores aiming straight toward the center of trunk to increase the chances of obtaining an accurate age estimation.