Don't blame the tool, blame the method. I put it to you that your new bit succeeded because it is brand new and therefore factory sharp. Use it a few times, sharpen it a few times, then try the same job again to see if it still does the job so easily.
40mm by 7cm is a big ask. You are much better off reaching full depth with a narrower bit in the first place, say 25mm, then repeating with the 40mm bit. By removing the core with a narrower bit to start with, you are lessening the work required of the larger bit by a vast amount, and your original one would probably have done the job.
