Weighing bullets & measuring bearing surface

[bozo699]

Mikecr - I agree with your statements - to me it simply stated that I am probably dealing with a batch of quality bullets that have lower than expected tolerances when using bearing surface as a baseline indicator (yep it can be argued that the nose or BT or meplat would be a better place to start). I may get lucky and the sum of the critical measurements may balance out - to me its just a red flag.

From here I can choose to just go and shoot or measure each of the critical areas, or finally make some assumptions based on effort vs reward and put my time elsewhere. Starting somehwere in the measurement game is at least letting me make informed choices.

The jury is out for me on which approach is best at this stage, but I guess that is in part what this thread is about...

I think this sums it up pretty good.
Wayne.

 

[mikecr]

I didn't mean to imply that it's a waste of time or anything.
Just that we should use caution with very tight tolerances, as they apply to the grand scheme of it all.
Hell, for those that grossly leave the pack, FIREFORMING bullets..

 

[in2deep]

I was loading Sierra 107's on a highly leveraged Forster Co-Axial press and thought life was good and never thought I needed to check the bullets individually till I started to seat bullets with an arbor press and hand-die and then the lights came on when some would go in easy and some were unable to seat even with excessive force.
Turns out several in the box had large globs (easy to see with the naked eye) of extra copper oozing out the base of the bullet enough to not allow them to seat without considerable pressure and clearly bending the necks way out of round while many others had a sharp ridge around the transition (should be rounded) where the tapered rear joined the bearing surface and those took considerable pressure on the arbor press and you could feel them "clunk" into the case and were clearly not uniform. The first 2 boxes didn't have these but the last box I opened (out of the same lot) had about 20.
Now I quickly look at each bullet and use the arbor press seating force to further confirm uniformity and cull the best ones to use for score. Some of this is neck tension related but after pulling a few bullets to check and confirm I can say for sure that you can weed out some grossly bad bullets by feel using an arbor press and most all these nasty bullets would have gone unnoticed in a regular press and surely some needed enough force to seat where the necks would have been bent out of round from the force and it explains why I used to get quite a few rounds that unexplainably measured way out on the concentricity gauge with all the rest being sub >.002 out.
This is not a knock on Sierra's as they are modestly priced compared to some custom JLK's I have (no need to check for bad ones) just that sometimes in looking for the smaller things we overlook the obvious.