Ring around bullet when using hornady bullet seating die

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gomeybear
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Re: Ring around bullet when using hornady bullet seating die

Post by gomeybear » Sat Jan 11, 2020 2:53 pm

Very informative dellet. How to figure out COAL when bullet is sitting on powder still is puzzling me. Should I open up the case neck a bit? There is some friction coming from the neck of the fired case still on the bullet; so it kinda feels like Im pushing too hard to get over that slight neck tension and it ends up feeling as though Im compressing powder and bullet is not just sitting with its own weight as pressure.

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dellet
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Re: Ring around bullet when using hornady bullet seating die

Post by dellet » Sat Jan 11, 2020 3:18 pm

gomeybear wrote:
Sat Jan 11, 2020 1:13 pm
Would seating bullet lower in the case increase pressure assuming charges are the same or decrease pressure? Yes Another words do I have to worry about working back up in charge weight when seating bullet lower like you would seating it longer?That depends

Also, which method works best typically with 125 sst and other fat bullets, making sure bullet is resting on powder charge or minimizing jump to rifling? yesThey impact each other; so, seems like you cant have it both ways maybe?No
This is the reason of the other epistle. You have two completely different things going on here. Partly my fault, but more so those that have quoted me without understanding what I am saying or giving a reference.

Finding where the bullet touches the powder is a method I use to cut down on load work ups. Certain powders are more consistent loaded certain ways. That could be with only half a case full, or compressed until the case bulges. I want to know where the touch is.

This is an almost always statement. Increasing the case volume of a loaded round (bullet out) will decrease start pressure and generally will decrease peak pressure. It can also increase peak pressure because your are at the same time decreasing chamber volume. Part of that will depend on the burn rate of the powder and how tight the chamber is. Moving the bullet in, decreasing case volume, will raise starting pressure and generally raise peak pressure. Quite simply, you're not ready for that yet, but be mindful those relation ships.

Lets just work this one load. 125 SST and 296/H110.

Published max is somewhere between 17.5 and 21 grains for a 125 grain bullet. COL is somewhere between 2.050 and 2.260". I can go here and get most bullet lengths http://www.jbmballistics.com/ballistics ... gths.shtml From there I can compare seated depth so I can duplicate published data if I want.

I find where the SST hits the lands, then what the COL or CBTO of that bullet sitting on 17.5 grains of powder and also 21 grains of powder. I now have a window of loaded length and charge weight. Generally I also have a target velocity that I know my rifle is accurate at. In a 16" barrel that's 22-2250 fps

Looking at published data i'm starting around 18 grains. 18 grains in a fired case, bullet set on top and measure add .010" and that gives me my loaded length to start with. The .010" gives a bit of room for a sized case.

Depending velocity of that load I will add or subtract powder. If powder changes .1 grain, seated depth will change .010". this keeps the ratio the same. When I get velocity, then I will play with seated depth for accuracy.

Keeping the powder ratio the same, helps keep pressure the same, even tho velocity increases. It's not a straight 1/1 but velocity will go up faster than pressure.

After peak firing pressure, the bullet sort of slows down, it actually accelerates slower. If the peak is high, that acceleration drops off faster. High peak pressure means, lower muzzle pressure. Lower peak, higher muzzle. Different rates of acceleration, can deliver the same velocity over the same distance.

Understanding how powder relates to pressure/space is the key to getting subs to cycle and how to fine tune a load.
gomeybear wrote:
Sat Jan 11, 2020 2:53 pm
Very informative dellet. How to figure out COAL when bullet is sitting on powder still is puzzling me. Should I open up the case neck a bit? There is some friction coming from the neck of the fired case still on the bullet; so it kinda feels like Im pushing too hard to get over that slight neck tension and it ends up feeling as though Im compressing powder and bullet is not just sitting with its own weight as pressure.


Use a fired case with primer.
300 Blackout, not just for sub-sonics.

gomeybear
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Re: Ring around bullet when using hornady bullet seating die

Post by gomeybear » Sat Jan 11, 2020 4:22 pm

Whats the max powder charge you’ve loaded to, Dellet. When you say 21 grains, have you tinkered in that range with 125 sst?

What I take from what you’re saying is that you can load beyond published book values if you adjust seating depth accordingly.

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dellet
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Re: Ring around bullet when using hornady bullet seating die

Post by dellet » Sat Jan 11, 2020 5:41 pm

gomeybear wrote:
Sat Jan 11, 2020 4:22 pm
Whats the max powder charge you’ve loaded to, Dellet. When you say 21 grains, have you tinkered in that range with 125 sst?

What I take from what you’re saying is that you can load beyond published book values if you adjust seating depth accordingly.
Without looking at notes I could not say the highest I have loaded to, probably wouldn't anyway. There are many ways to exceed published data safely and at least twice as many ways to do it unsafely.

That's a topic for another time, get the basics down first.

Sadly the server many of my photos were on crashed and I'm not sure if they will ever come back, but these threads may be of interest
viewtopic.php?f=141&t=96500

viewtopic.php?f=128&t=99464
300 Blackout, not just for sub-sonics.

gomeybear
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Re: Ring around bullet when using hornady bullet seating die

Post by gomeybear » Mon Jan 20, 2020 2:54 pm

Do y’all use graphite powder or other dry lube on case necks to reduce bullet seating pressure? Ive heard this is a good practice in general to have better bullet release too; seems like an easy enough thing to incorporate into my reloading process.

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Re: Ring around bullet when using hornady bullet seating die

Post by gomeybear » Wed Jan 22, 2020 7:53 pm

To close up this thread, a quick update. I ordered a #11 expander ball from Hornady, think its maybe for a 7.62x39. The one in the 300 blackout hornady die is #10. Problem solved necks are right at .306” when sized now. For some reason the #10 was closer to .302~.303 ish. Anyways.... that ring that was showing up was very faint after some of the fine tuning that I implemented at y’alls suggestions. Now that I was able to increase the neck diameter to .306 effectively changing that neck tension, even the faintest ring is no long there at all - its gone now. So y’all were right it was mostly neck tension that was the culprit. If anyone has a similar issue with Hornady Custom 300 blackout dies - might want to order the #11 expander ball see if that solves the issue.

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