Brain Fart

finnbear270

Well-Known Member
Been given some pointers for case H20 measuring, Had syringes already from squirting small amounts of lube into small spaces like trigger units, So weigh empty cases with a seated bullet of choice, (Minus primer), Fill cases with water till overflowing, dry off excess to primer recess & any on outside of cases, ...................... F###'# H***, How do you stand these up on the powder scale?
:-| ? Weigh portion of Blue tack, re zero scales, mould Blue tack into a stand for water filled case.
 

SCC

Well-Known Member
So far I measure my fired case volume with primer still in, but not with a seated bullet/head.....
Like this if it helps....
 

Steff

Well-Known Member
A pint too may during lunch?🤣

You water-meter fired cases with the primer in place, not the bullet.
 

GrizZLy9

Active Member
Sounds like you're after useable case capacity - see here:
Just watch out for trapped air bubbles.
 
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Steff

Well-Known Member
See here:

This is complete BS. Case capacity HAS to be measured from a FiRED case from the gun you want to load for. On ignition the powder will expand the case in the chamber. A wider chamber will render more expansion volume and thereby less pressure.
 

finnbear270

Well-Known Member
I wanted the "Actual" usable H20 capacity for my own preferred load,Using a fired case, not just a full case of water to the neck.
I hadn't seen that video, Think the video poster may be the originator of P Max, so I wouldn't be jumping in to rubbish the method, without completely understanding internal ballistics calculators.
 

Steff

Well-Known Member
I wanted the "Actual" usable H20 capacity for my own preferred load,Using a fired case, not just a full case of water to the neck.
I hadn't seen that video, Think the video poster may be the originator of P Max, so I wouldn't be jumping in to rubbish the method, without completely understanding internal ballistics calculators.
And what do you do with that?
 

mealiejimmy

Well-Known Member
So how do you guys do the other method then?, How do you calculate the reduction in H20 to allow for your bullet?.
If you use Quickload, then you can input the actual total case capacity using a fired case with the primer still in place.
Quick load calculates nett case capacity when you tell it the bullet you are using and the col

Cheers

Bruce
 

SCC

Well-Known Member
GRT (Gordons Reloading Tool) also shows you the effective case volume affter you select the bullet type, input the volume of H2O and the COL.
1627470416719.png

If you dont have QL then GRT is a good alternative ...and free to download and use once you register on the site.
Gordons Reloading Tool

ATB,
SCC
 

GrizZLy9

Active Member
This is complete BS. Case capacity HAS to be measured from a FiRED case from the gun you want to load for. On ignition the powder will expand the case in the chamber. A wider chamber will render more expansion volume and thereby less pressure.
Who said anything about not using a fired case from your chamber? With the BBT P-Max program, the user is required to enter the usable case capacity; that is, the case capacity behind the seated bullet.
 

finnbear270

Well-Known Member
This is complete BS. Case capacity HAS to be measured from a FiRED case from the gun you want to load for. On ignition the powder will expand the case in the chamber. A wider chamber will render more expansion volume and thereby less pressure.
Maybe you should consider that not all of us on here are newbies at reloading, Myself , been doing it for a good many years now, using the tried and tested manufacturers data, Just recently venturing into the lesser known regions of newer cartridges, and even newer to me ways of going about reloading, rather than sticking at ladder rung number one.
I certainly do not require anyone to jump in assuming I'm a backwoodsman, who might not know the difference between a new unfired case & one that is fire formed.:tiphat:
 

Steff

Well-Known Member
Who said anything about not using a fired case from your chamber? With the BBT P-Max program, the user is required to enter the usable case capacity; that is, the case capacity behind the seated bullet.
I have to admit that I am not familiar with P-Max. But even so, in order to seat the bullet the case needs to be sized, at least the neck. What you can then measure, as in the vid, is the available capcity for unburnt powder. If this what P-Max uses, fine. But what is missing is the available expansion room on firing. If P-Max does not take this into consideration, it can hardly be very good at predicting pressure.
Both GRT and QL use exactly this, the capacity of an unsized case up to rim of the neck.
 

finnbear270

Well-Known Member
I have to admit that I am not familiar with P-Max. But even so, in order to seat the bullet the case needs to be sized, at least the neck. What you can then measure, as in the vid, is the available capcity for unburnt powder. If this what P-Max uses, fine. But what is missing is the available expansion room on firing. If P-Max does not take this into consideration, it can hardly be very good at predicting pressure.
Both GRT and QL use exactly this, the capacity of an unsized case up to rim of the neck.
Topsy turvy this is, also a bit shall I venture ****ed?
 

borbal

Well-Known Member
I have to admit that I am not familiar with P-Max. But even so, in order to seat the bullet the case needs to be sized, at least the neck. What you can then measure, as in the vid, is the available capcity for unburnt powder. If this what P-Max uses, fine.
That is what P-Max uses. The video does not mention this step and perhaps it should. You just need to resize the top of the neck - or give the neck a slight squeeze to deform it slightly - so the bullet will stay in the case.
 
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