At times such factory loads shoot accurate because most manufacturers of ammunition for big bore DR try to remain as close as possible to the ballistic values of the old ammunition, above all from Kynoch with which many old double rifles were regulated. However, a problem remains with the modern bullets because nowadays they have much thicker walls than in the past and this is already noticeable by some loads. I also reload cartridges caliber 577 Nitro Express and have clearly better results when I use the old thin-walled bullets from Kynoch. With the bullets from Woodleigh I have to reduce the loads for the same result. You cannot always take the loads as stated in some manuals, and the powder has also to be chosen correctly. It is not always easy to find such loads and therefore requires a supply of components. If you don't reload yourself you will spend in the end a lot of money for a perhaps uncertain result.