Thread: MEPLAT TRIMMING

If your just cutting the lead tip off a SP a very sharp stanley knife does a good job with care.
But I agree a jig of some sort would be good or a DIY attachment on a case trimmer perhaps.

Originally Posted by johnd

@zimmer I have a bunch of the 155 nosler custom projo's the tips are often ragged and angled, my thoughts while inactive was to trim them to an eveness.
Luckily I dont shoot them past 600 yd (and i know some do) so will most likely never proove if its good or not and i can obviously just shoot them how they are but like i say just looking for a non demanding bed rest job.
I have already invested time into the joy of OAL bullet sorting and thats been quite a revelation with just the CC's My stash of HBC's are the tipped variety so I wont be touching them with a trimmer, but I will get on to sorting them and possibly individual nameing. I'm thinking X is a cool name for a projectile, and of course i can always call the bad ones, three.
Just need to get my laser 3 d printer sorted.

Re the lower BC from trimming, I find it weird that I can have a raggedy end, mass produced bullet that shoots lets say .45 BC and yet by trimming it to even that its going to go into the high .300 low .4's

Apparently - as I had a fair bit of time to read crap recently as well haha - the bullet's tip doesn't actually contact the fluid in front of the pill in the case of target-type bullets with a fine tip. That's why it doesn't make a huge difference having a ragged hole vs a tiny hole vs no hole if the profile is the same. What does make a difference is going from a small tip, to a slightly wider tip (i.e. trimmed) as that alters the point the pressure hits the ogive (or point of drag creation) on the 'shoulder' of the bullet. A nice pic of a bullet in flight showing the shockwaves would be awesome right about here - anyone? I think that's what zimmer was alluding to with the comment that trimming must be followed by tipping - as the BC is governed by the point the shockwave is created off the bullet's ogive or shoulder and that forms is sensitive to the profile of the tip.

A sideline issue, is bullets off several sets of machinery each having slightly different ogive profiles - same weight etc but slight variances in jackets and cores and final closing up of the jackets can all add up to a surprising difference in performance if the ogives aren't identical. I made a gauge once out of ali sheet and just roughly filed it to a neat fit on a mumble-brand target pill as I was getting two groups. Ended up with three distinct profiles in the pills! Why I got two groups I have no idea, and after that I still got two groups just separating them out meant that the two groups weren't at the same time. Dumbarse separated them, loaded them and put them in two separate boxes but didn't record which was which so it was a lottery which POI I was going to get - useful as a knowledge exercise and how anal you have to be about detail recording but not so much for using them for target work. Became practice rounds and I never went and got more.