The thought behind trimming the meplat is not to make the BC higher, but rather more consistent. It is estimated a shooter will reduce the BC of a bullet by about 2% when trimming. This loss is offset by a more consistent bullet meplat shape, which in turn - should result in tighter groups. Several bench rest shooters have been doing this. Some swear that their groups have become more consiostent and tighter, while other have found no discernable difference. While the jury is still out on this practice, all invilved generally agree that were no negative consequences to uniforming the meplat.
Bench rest shooters have taken the next step of repointing the uniformed tip to either get back the BC lost during the first step, or improve the BC by closing up the meplat entirely.
I don't recall any specific studies being done on this meplat uniforming - just anecdotal response from shooters based on their own findings. Intuitively, it stands to reason that when a meplat is trimmed, it opens up the "hollowpoint" ever so slightly, which should start the expansion process a little sooner. There are a couple other threads on LRH dealing with berger bullets (specifically the 210 grain in 30 cal) that failed to open after hitting an animal.
Pics of Berger Bullets NOT Performing????
The evidence seems to be pointing to a plugged up hollowpoint in some of the bullets. I know I have found a few out of a box of 100 that were that way. But this doesn't seem to matter as much with the big 300 grainers in 338 cal.
Berger was going to do some testing, but it is unclear if that was/is the cause for the expansion failure. By trimming the meplat and the chamfering the rim to make it uniform, I believe expansion abilities are enhanced. This could be detrimantal at short range, but an advantage at longer ranges. In the end, better bullet consistency is what the shooter is striving for.