Seating depth variance of .005

[dinmax82]

Been having issues with seating depth variances of 2.190-2.185 Base to OGIVE.

I stainless tumble and dip in graphite to help smooth it out. Doesn't matter if whidden or forster seating dies.

I load with a Co-ax press and trying to keep the handle pull pretty consistent.

Anything I should look for or is this acceptable?

 

[dmoran]

Measure some of the bullets from the "base to ogive".
Likely most the variance could be in the bullets.
Segregating bullets goes along ways for equality in seating depth.
Donovan

 

[Terry]

It could be the bullets.

 

[Terry]

Measure some of the bullets from the "base to ogive".
Likely most the variance is in the bullets.
Donovan

You type faster!

 

[Dusty Stevens]

Crushing powder does that too

 

[dinmax82]

Only 42.7 H4350 in this last batch of 6.5CM with Hornady brass, looks like plenty of space.

I'll measure my bullet ogives but didn't think it'd make a difference. Where the the seater touch the bullet? Would that be the determining factor?

 

[wedgy]

Only 42.7 H4350 in this last batch of 6.5CM with Hornady brass, looks like plenty of space.

I'll measure my bullet ogives but didn't think it'd make a difference. Where the the seater touch the bullet? Would that be the determining factor?

You might try a different stem, I know Redding makes a VLD stem, different from the standard stem. Is seating pressure the same ? If not could be varying neck tension. Any marks on the bullets ? I have seen where some bed the stem with epoxy but have never done it. Try a different bullet and see if results are the same.

 

[dmoran]

@dinmax82
Same as one does for "base to ogive", you could use the seater stem from your die, using it to measure "base to seater" instead. Which is a good way, that will yield the exact variance to be expected when seating.
From which, any further variance can be pin-pointed and related to other aspects.
Donovan

 

[Campbell]

Wow! What a coincidence, I too have been noticing this!

I have measured ogive to base on my HBC 155gr bullets and it is difficult to get lower than a .005 consistency.

What I do is the "wiggle and turn" whilst closing the calliper on my vernier gauge in order to batch my bullets.

Furthermore, one has to take account of where the bullet seating tip engages with the tip. I guess that if the bullet is not perfectly perpendicular in the case whilst been seated, then this will also cause inconsistency in ogive to cartridge base (every thing else been equal)

 

[Campbell]

@dinmax82
Same as one does for "base to ogive", you could use the seater stem from your die, using it to measure "base to seater" instead. Which is a good way, that will yield the exact variance to be expected when seating.
From which, any further variance can be pin-pointed and related to other aspects.
Donovan

Hi Donovan

How does one use the seater stem to measure "base to seater". It sounds very logical, but how?

 

[Richard Coody]

Been having issues with seating depth variances of 2.190-2.185 Base to OGIVE.

I stainless tumble and dip in graphite to help smooth it out. Doesn't matter if whidden or forster seating dies.

I load with a Co-ax press and trying to keep the handle pull pretty consistent.

Anything I should look for or is this acceptable?

.005 is a pretty small variance. lots of things could be causing it. what is the rifles intended use.

has all the brass been fired the same number of times?
are you annealing?
personally i like to leave the carbon in the necks. you would be suprised how much your seating force varies (an indicator of neck tension) if you could seat some bullets with a force indicator gauge.

probably the most likely culprit is inconsistent ogive on your bullets. Aren't using hornady by chance?

 

[dinmax82]

.005 is a pretty small variance. lots of things could be causing it. what is the rifles intended use.

has all the brass been fired the same number of times?
are you annealing?
personally i like to leave the carbon in the necks. you would be suprised how much your seating force varies (an indicator of neck tension) if you could seat some bullets with a force indicator gauge.

probably the most likely culprit is inconsistent ogive on your bullets. Aren't using hornady by chance?

I use my rifles to shoot small groups...

Brass firings vary
I do annneal, not every time though.
I use the graphite to try to have seating force the same, although I do feel differences but on the obvious ones the measurements aren't off most of the times. Total crapshoot.

I'm using berger 140 hybrids for most everything.

 

[dmoran]

@Campbell
Myself, prefer to do it with a dial-indicator stand, but can also be done with a caliper or micrometer.
Took this picture for you, showing my dial-indicator setup, and also with a caliper.
Donovan

 

[dmoran]

.005 is a pretty small variance.....

To me, a seating variance of 0.005" is a lot. Where to say 0.005" in seating will make a difference on many of my developed loads accuracy levels, and enough to effect vertical dispersion some what grossly.

Personally I strive for less then 0.001", and pretty fussy to be under a 1/2-thousandths on match ammo.
Donovan

 

[Down South]

To me, a seating variance of 0.005" is a lot. Where to say 0.005" in seating will make a difference on many of my developed loads accuracy levels, and enough to effect vertical dispersion some what grossly.

Personally I strive for less then 0.001", and pretty fussy to be under a 1/2-thousandths on match ammo.
Donovan

Same here........

 

[jimmymac]

I'd get seating depth variation similar to what the OP indicated when I use my Forster seater die in my rock chucker. That variation went away when I moved to an inline seater die and arbor press.

Like what was said above. I won't tolerate 5 thousandths variation. To me that is a lot. At that rate I'd never find the right seating depth.

 

[hrlincoln]

I use my rifles to shoot small groups...

I'm using berger 140 hybrids for most everything.

The 140 hybrids will most likely benefit using a VLD seating stem for more consistent seating as wedgy suggested...they have a rather pointy nose profile and it may be that your current seating stem is contacting the meplat instead of the ogive. Not hard to vary .005 with press linkage play and inconsistent meplats.

 

[Mikemci]

.005" variance is unacceptable for accurate loads. When you get your charge weight right, you will fine tune it at less than .005" changes in seating depth.

 

[jr600yd]

Check your neck wall thickness. If they're not all the same it will cause different seating depths.

 

[Twoboxer]

. . . I'll measure my bullet ogives but didn't think it'd make a difference. Where the the seater touch the bullet? Would that be the determining factor?

Yes. Assuming the press/die isn't broken, most likely problem is the place where the seating stem contacts the bullet is not the same distance from the bullet ogive on every bullet. In it's opinion the press is seating to the same point every time, but the ogive doesn't end up in the same place every time.

If you want identical CBTOs, the easiest way I've found is to use a micrometer seating die, seat a bit long, measure CBTO, adjust the micrometer, and seat again.