matching loads by seating depth 9mm

S

Shadow9mm

New member
so I finished testing on some 124g speer gold dots. I generally use 124g berrys round nose for training and practice and wanted to match the loads for training purposes.

bullet length measured with micrometer
gold dot 0.5588
Berrys 0.5890
Diference 0.0302

listed COL
Gold Dot 1.120
Berrys 1.160
Difference .040

In theory if I seat the Berry's to 1.150 it should put the base of the bullet in the same place in the case giving me the same case capacity if I am thinking about this correctly.

The loads from Speer are a bit higher than published in some other manuals, but I worked them up and feel they are safe in my guns with the gold dot based on my testing. So in theory if I work this load up from start using the Berrys bullets with the Speer data and modified seating depth it should be within safe ranges as well as I am using the same case capacity right?

Or am I thinking about this wrong? It there more involved, am I over simplifying this? What else should I be considering?
 
What else should I be considering?
Click to expand...

what else should you be considering? probably lots of things. Here's a couple I just thought of....

Where on each bullet does your seating stem contact it??

When you're looking to seat the bullet base in the same spot in the case with different length bullets, you need to see how much of the difference in bullet length is "above" where the seating stem contacts the slug.

The key here is to find out if the distance between the base of the bullet and where the seating stem bears on it is the same for both bullets. IF it is, you're good, and all the difference in bullet length from where the seating stem contacts the slug to its tip is irrelevant to seating depth in the case.

As long as your COAL is within industry max and the round feeds in your gun, it doesn't matter exactly how long the round is.

The other thing, since it appears you're wanting to make the powder space identical, in order to match load performance, is what is the difference in pressure and velocity between the jacketed and plated bullets you plan to use when you have identical powder space and load?

Third, WILL it make a practical difference?? and by that I mean one that makes a difference downrange, from your gun, in your hands, not just one you can measure using the specs.

For example, (and only for example) what if, using identical everything but the bullets, your Gold Dots hit one place and give teeny groups, and your Berry's hit somewhere else and group poorly??

Just some things to consider, and decide if, and how much, they apply to what you're doing.
 
I want to make sure I'm reading what you said correctly...

If you take the Berry's bullet and do the proper load work-up then YES, I say you are absolutely safe.

What you should not do is take your experience and results with the Gold Dot bullet and then just swap in a bullet from a different manufacturer without doing the load work-up.

The actual bullet diameter, bearing surface and make-up of the bullet itself all differs, so results can/will differ.

I can also say that I have seen with my own loads (in 9mm for certain!) that brass matters. Different head stamp 9mm brass has shown me different pressure signs with loads at/near max. A load done exactly the same in every single way EXCEPT brass has shown me pressure signs I did not like in some brass that it didn't in other brass.

My theory is that this can be the case in any/every different caliber, but this is magnified in 9mm where you have a small case and high pressure.
 
between the jacketed and plated bullets
Click to expand...
I was under the impression that Gold Dots are actually a plated bullet, and the Berry's are a plated bullet.

Even still, they are not the same, I wouldn't expect them to act the same under pressure.
 
Yes, i always work up from start. I like my guns, fingers, and face just the way they are :) just bring cautious since im modifying loads and based on past experience these loads are stout.

I expect i will have to tune them to match a little. But one only way to know is to test and put them on paper.
 
Shadow9mm said:
So in theory if I work this load up from start using the Berrys bullets with the Speer data and modified seating depth it should be within safe ranges as well as I am using the same case capacity right?
Click to expand...

How will you know they are both safe pressure levels? I’m not being facetious, I don’t know how to know my pressure level very precisely in pistol load development. I rely on good data, recoil and pressure signs from factory vs loaded ammo.
 
So this is presuming the data in the manual is safe. I work the load up looking at velocity, perceived recoil, and pressure signs, on comparison to factory loads. My thinking was same weight bullet and same case capacity due to the bases of the bullets being matched should produce the same or very similar pressure and velocity. Obviously still working the load up. But it should give the same recoil and pointnof impact for training purposes.

Granted this is a theory. Kind of what i am trying to figure out.
 
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