Case OAL VS pressure?

[Evil_Dark]

Ok, so I think I should give some clarifications.

I did the chamber measurment with the cleaning rod method with the exact bullet that I am developing a load for. I just can measure the COAL because I don't hsve any device to measure it by the ogive. I know that it's not the best and accurate way, but it's the only I have. So tht being said, my COAL measured with the cleaning rod is actually 2.630", I was very surprised. So I tried the splitted neck method, and now it gaved me more decent results, 2.996" (tried several times, it gaved me +- 0.002" on each test so I think I have a good measure). So you guys were right, I am surely not pushing my bullet 0.250" in the rifling.

When I was saying DEEPER, I was talking about the bullet in the brass, so DEEPER = shorter COAL.

I was trying to understand why my velocities were getting higher when I seated my bullets to have a longer COAL.

But anyway thanks a lot to all of you for your inputs, I learned a lot.

Bigedp51: Everyone is free to answer in this forum, you should not be insulted about someone giving it's opinion more often than you. And I don't find it offensive or misapropriate that Ron AKA uses another guy picture to demonstrate what he mean, as I didn't had the impression that Ron AKA was trying to take the credit about this idea/process/picture.
That being said, I also wanted to thank you too (bigedp51) for the links and clear information that you provided me at the begining of this post, as these were accurate and on point.

Regards,

Dark

 

[bigedp51]

Bigedp51: Everyone is free to answer in this forum, you should not be insulted about someone giving it's opinion more often than you. And I don't find it offensive or misapropriate that Ron AKA uses another guy picture to demonstrate what he mean, as I didn't had the impression that Ron AKA was trying to take the credit about this idea/process/picture.
That being said, I also wanted to thank you too (bigedp51) for the links and clear information that you provided me at the begining of this post, as these were accurate and on point.

Regards, Dark

I never said a word here to Ron AKA until he told us lubing your cases to fire form them was OK to do, And when Ron AKA said I did not understand and that he was an engineer really angered me. Lubing cases increases bolt thrust and especially on older rifles made of softer steels it can increase headspace very quickly and "THAT" Ron AKA the engineer does not understand.

The warning below is from the Lyman reloading manual.

The warning below is from the H.P. White Testing Labratory.

Also Ron AKA has said there are no differences in primers in cup thickness or hardness which was also a big mistake. My issue with Ron AKA is he is just repeating what he has read in other postings and is far from being a expert on anything. And you can simply tell this from reading his postings here and other websites.

Ron AKA tells us he has been reloading for over 50 years, and yet in those 50 years he has never tried to partial neck resize. Give me a break, what did any of you do when you only had a full length resizing die when you wanted to neck size only. How many have you read about only sizing half the neck? How many of you know BS when you see it, and from the PMs I'm getting there are a few of you with very good BS meters.

If you try to neck size only the case length at the shoulder probably grows some due to the body being squeezed down quite a bit. And if your chamber is on the short side, you may be running out of headspace, even if you do a full resize. You may have to lap down a shell holder to get the case into the die far enough to bump the shoulder.

This is a little disappointing to hear, as I have a RCBS set of dies and planned to do a partial neck resize. I may not be able to do it either.

Anything you read in a forum or on the web should be double and triple checked, so learn what a poser is and what a parrot does.

WARNING

Be advised, in many forums we have midgets sitting at their computers pretending to be giants.

 

[bigedp51]

Hi All, I just not sure that i'm correct...

The same Case/powder charge/bullet will give less pressure if I seat the bullet deeper, right? Or is the inverse?
I'm in doubt and I just wanted to be sure.

Thanks to enlighten me!

Dark

Any time you seat the bullet deeper or longer than the recommended OAL the chamber pressure will increase with the same powder charge.

In the mid 1960s the U.S. Army had Remington who was running the Lake City Army Ammunition Plant do a study on seating length with various powders they used. This study was because the military had different standards in chambers, throat length, case capacities and seating depths. This study was in depth with pressures monitored the length of the barrel, and even went into bullet upset in the bore and the increase in bore diameter with new and worn barrels.

Bottom line, if you seat the bullet deeper you decrease case capacity and raise the chamber pressure. If you seat the bullet long it is moved closer to the rifling with less jump and the chamber pressure will increase. The manuals have the seating depth in the middle for that listed bullet at the safest starting pressure.

Many reloaders jam their bullets and this increases the start pressure and when the chamber pressure peaks. And this must be compensated for with you loads and your rifle.

This is why you are told in reloading manuals to make workup loads and start low and work up looking for signs of pressure.

Below is a link and the "long" version of the story. (Take your shoes and socks off and grab a scientific calculator, it gets deep)

https://deepblue.lib.umich.edu/bitstream/handle/2027.42/3866/bac6873.0001.001.pdf?sequence=5