I have a 6mm designed by By Smalley of Utah. By was a rocket engineer and knew his business. He swore by the "short fat" rule for all his cartridges up to his 5mm to 6.5mm. By worked with Mick McFerson to develop the 5mm and 6.5mm.
Trimming the meplat does lower the BC of the bullet, However, by then reforming all meplats you will increase the BC. Perhaps higher than it was with the irregular meplat as it origionally was!!
AND you will have made all the bullets extremely consistent for a much lower velocity...