unusual bullet seating issue

[noload]

Now that they are fired ...slide a bullet in the fired neck and check for donuts.

 

[taliv]

i slid a bullet in the neck and couldn't really feel anything so i said screw it and just dremeled a case in half.

these pics are of the 3x fired, annealed, fired a fourth time brass that was seating 020 deeper
I noticed some flash from the dremel after looking at the first picture so i picked it off a bit and took a second pic.

 

[noload]

If you can't feel a donut with a bullet slid in the neck, you don't have a donut to speak of.

 

[barefooter56]

my question is what could possibly make a bullet seat deeper in one group of cases than another? i mean, what physical force

assume same cartridge (6.5x47), bullets (140hybrid) etc. in this situation, 3 different seating dies (wilson, redding, forster) were used and without changing anything on the seating die, bullets in one group were seated consistently .020" deeper than another group. Very repeatable.

There is a difference in the cases between the two groups (number of times fired) but put that aside for a moment.

I can see how a couple of things could cause this:
1. bullets sticking in the seater and being pulled up slightly before releasing - but in this case, there is no mark from the stem and i'm using moderately light neck tension, and i would expect the consistency of the depth to vary much more than it does

2. compressed powder pushing the bullets back up - but in this case, these are nowhere close to compressed loads


so what else am i missing?
bullets are either being pushed to the same depth, and one of them is coming back up
or one is not being pushed as far as the other.

is it possible that the brass is springy and the brass itself is moving in the seating process? given the original use of wilson hand seater and small arbor press, i don't think i'm using enough force to move the brass 20 thou

thanks for any thoughts

taliv,
Question. Which seating die was used when you got the .020 seating depth issue ?
Take care,

 

[taliv]

barefoot, all 3 seating dies showed the same .020 difference. I normally seat with wilson hand dies. we noticed the issue, then tested with the two others and they did exact same thing. so we concluded it had nothing to do with the die.

 

[barefooter56]

barefoot, all 3 seating dies showed the same .020 difference. I normally seat with wilson hand dies. we noticed the issue, then tested with the two others and they did exact same thing. so we concluded it had nothing to do with the die.

taliv,
Did the Wilson and Redding dies have a VLD seater stem installed in them and did you check to see if the tip of the bullet was "bottoming out" in the seater stem ? Usually that is the cause of such large variances in seating depth. A bullets base to tip variation can be that large. That's why we use the base to ogive. Still get variances but they are a lot smaller.

 

[Zero333]

Did you size after annealing or before ???

If you annealed After sizing, the neck pull tension would be less on those cases. Maybe that would allow a floating seating stem to seat the bullets deeper ???

Just throwing ideas around. Ignore my comment if it sounds crazy.

 

[taliv]

barefoot, good question. whatever came from the factory for 6.5x47 dies. i didn't change it. i didn't check to see if bullet tip was hitting stem either, but i'd be really surprised. how do you suggest i test that?
i'm pretty sure i don't have 20 thou variance in tips, but i can see how if the seater pressure is all on that one point that it would give a big variation in seating depths because it would flex a lot more at the tip than ogive

that's the most promising theory so far. definitely will look into it. thanks!

zero, i always anneal before sizing

 

[barefooter56]

barefoot, good question. whatever came from the factory for 6.5x47 dies. i didn't change it. i didn't check to see if bullet tip was hitting stem either, but i'd be really surprised. how do you suggest i test that?
i'm pretty sure i don't have 20 thou variance in tips, but i can see how if the seater pressure is all on that one point that it would give a big variation in seating depths because it would flex a lot more at the tip than ogive

that's the most promising theory so far. definitely will look into it. thanks!

zero, i always anneal before sizing

taliv,
Remove the seater stems from the die(s) and take a sample of bullets. If the bullet isnt "cupped" by the opening on the stem but is rather "wobbly" for lack of a better word. You've confirmed that the tips are bottoming out in the stem.

 

[taliv]

well, it's likely they are very close though, right? so let's say i'm only 1 thou from the longer tips touching. as i start to seat, it will touch and then crush it. right? in that case, the wiggle test would be false negative

 

[barefooter56]

well, it's likely they are very close though, right? so let's say i'm only 1 thou from the longer tips touching. as i start to seat, it will touch and then crush it. right? in that case, the wiggle test would be false negative

taliv,
My advice, never assume. The bullet starts moving before the crush starts maybe? That you are not applying pressure to the bullet when its inserted in the seater stem like you would when seating a bullet. Try it. All hypothesis should be tested.

 

[taliv]

just an update:

still no definitive explanation, but doubling neck tension made the "problem" go away, meaning, all my brass seats to same depth whether it's annealed or not. (specifically, sizing the full neck, not using a smaller bushing)

i also tried seating 10 thou farther out and no issues

 

[243winxb]

Taliv, measure the neck diameter before and after seating a bullet with a micrometer. Whats the difference?