Reducing ES

[terryh]

PbG,

Yup, the primers themselves can be manufactured within a large tolerance - this you can do nothing about.

By unfirming the pockets you are at least removing one set of tolerances , by seating to a consistent depth you are removing another.

so from my perspective, and to steal a songs title '2 out of 3 ain't bad' ☺️ - or put it another way, better than not bothering?

I also concur with Andrews comment, most of the efforts put in by folks to 'pick the fly sh*t out of the pepper' re. reloading is negated by the fact that misreading the wind at a couple of mph negates a reduction in group size from 1/2" to 3/8" i.e feels good but not real in practical terms (bit like masturbation if I'm being crude! 😲)

T

[Popsbengo]

13 minutes ago, terryh said:

PbG,

Yup, the primers themselves can be manufactured within a large tolerance - this you can do nothing about.

By unfirming the pockets you are at least removing one set of tolerances , by seating to a consistent depth you are removing another

well you can measure the cups - I do,  and weigh them as there's no other way to estimate the amount of primer compound.  Can't say weighing was worthwhile by results seen.  I use BR2 / BR4 CCI which should already be higher spec than 'ordinary' primers (or are they!?).

I agree uniforming the pockets helps but seating depth is set by that isn't it? If not either one is risking crushing or under-seating the primer.  This is why I can't see the value in a dial-gauge seating system

[terryh]

PbG,

Surely that 'is' the idea of controlled seating of primer, to apply the same amount of 'crush'/preload on the primers anvil (or whatever that bit is called?), analogous to timing of a cars ignition, you set off the charge at the same point in time vs firing pin travel = same point when all the various vibrations start.

NB, avoiding not applying any crush. 

Also I've now contradicted myself as my current shooting abilities are not the this level on ammunition consistency worries.

[No i deer]

2 hours ago, Popsbengo said:

Little point in pocket uniforming unless primers are sorted for depth too.  I attach the SAAMI spec drawing.  You can see the allowable tolerances are large - 13thou on depth of primer cup for LRP.

I've never measured a primer depth 😂🤣🤪.

Pops you got anorak syndrome 😱

[Popsbengo]

1 hour ago, No i deer said:

I've never measured a primer depth 😂🤣🤪.

Pops you got anorak syndrome 😱

Oh dear,  I may have,

[furrybean]

1 hour ago, Popsbengo said:

well you can measure the cups - I do,  and weigh them as there's no other way to estimate the amount of primer compound.  Can't say weighing was worthwhile by results seen.  I use BR2 / BR4 CCI which should already be higher spec than 'ordinary' primers (or are they!?).

I agree uniforming the pockets helps but seating depth is set by that isn't it? If not either one is risking crushing or under-seating the primer.  This is why I can't see the value in a dial-gauge seating system

PGB

Are you thinking that variations in seating depth could contribute to varying energy of ignition, or purely the extra distance needed for the firing pin to travel?

[Ronin]

My example was for reloading for competition (F Class ) where any variable need to be reduced to nominal level 

The but behind the bolt being the limiting factor (in my case)

[Popsbengo]

10 minutes ago, furrybean said:

PGB

Are you thinking that variations in seating depth could contribute to varying energy of ignition, or purely the extra distance needed for the firing pin to travel?

A bit of both;

Poorly seated primers may absorb firing pin energy as they are pushed forward under the impact, differing seating/primer cup depth will alter the lock-time by milli seconds - does this matter?  I don't know.  I do know that it's easy to reduce those variables (if only making small quantities of rounds) so I do.

Like so much in reloading we don't have large enough samples of data where variables can be held static to investigate what definitively works.  We make educated assumptions (guesses) and proceed.

[ds1]

This is a good place to start:

There is a balancing act between not wasting time reinventing the wheel and experimenting for yourself.

One example and it is about reducing ES is equating seating pressure to neck tension...... I took 6 fired cases  - 3 I left uncleaned  and 3 I polished the crap out  of the inside of the neck with steel wool and polishing paste. I then neck sized them with the same bushing ( and trimmed them) - so equal neck tension but massive difference in seating pressure (or so I could feel on the co-ax press with the polished ones being much  lighter to seat. . Next 6 more cases that had been through the Lem cleaner - inside of necks left like that - 3 through the same bushing die as before and three through an expander mandrel which which enlarges the ID by about 0.0005”, so neck tension had changed - on the co-ax hard to feel the difference when seating a bullet. Real world testing for me - rounds loaded with just the Redding body die and bushing neck die produced less ES and marginally better groups than ones loaded with the neck bushing die and expander mandrel after - this seems contrary to what others have found - I don’t really care - I can find what works for me.