OAL spread

[SCSAJack]

Looking through this forum. Many different OAL’s listed for there load. Isn’t a 9mm chamber a standard size? So checking a for getting the loaded round as close the the rifling with out touching . Second is mag fitting.. in SC the gun must work 100% so accuracy come second. Longest shot is 35yds and a 18x 36 in plate

[togmaster]

All 9mm chambers are not equal.

 

https://www.shockbottle.com/faqs-1

[4n2t0]

No, all chambers are not the same. Also, as long as the rounds aren't loaded very long they should function properly in the magazine. Testing for function and accuracy is a must.

 

Here's a similar topic posted just a few days ago...
 

 

Here's more information:

 

 

This is CZ 75 specific, but the same principals apply to all chambers. You can see how different bullet profiles affect the OAL. This same bullet lineup can/will plunk at different length depending on the barrel/bullet combo. e.g. All the bullets below successfully plunk at 1.159 in an M&P 9 (not reality, just an example).

 

 

 

Edited July 10 by 4n2t0

[shred]

This.  Not only are there two different current specifications for 9x19 chambers-- CIP and SAAMI, those chambers have been made for more than 100 years in 100 different countries so they are all over the map.  Even when we buy "SAAMI-spec" reamers to make case gauges, we have to test them and measure them to see if they really are where they are supposed to be. 

 

Most manufacturers don't seem to bother with that part if the resulting chamber passes the Go & No-Go pins.

 

Since measuring to the leade intersection absolutely sucks, everyone uses "OAL" although the important part is actually "where the fat part of your particular bullet hits the leade", and there's also a zillion different bullet shapes out there.

 

 

 

 

[SCSAJack]

Thanks or your responses,  gives me more to overthink this reloading process.

deeper you seat the bullet increases pressure

tighter crimping increases pressure

Is chamber pressure directly connected to recoil?

[perttime]

28 minutes ago, SCSAJack said:

...

Is chamber pressure directly connected to recoil?

No.

Chamber pressure depends, among other things, on which powder you use. A small amount of fast burning powder can generate high pressures - for a short duration -  but bullet velocity isn't necessarily high. A slower burning powder usually generates pressure for a a longer time, and more velocity.

 

Recoil mainly depends on bullet weight and velocity.

Edited July 11 by perttime

[4n2t0]

2 hours ago, SCSAJack said:

Thanks or your responses,  gives me more to overthink this reloading process.

deeper you seat the bullet increases pressure

tighter crimping increases pressure

Is chamber pressure directly connected to recoil?

 

You're definitely doing some of this, lol. Determine the max OAL for your bullet/barrel combo, use a published charge weight window, and crimp somewhere between .377 - .379 at the case mouth for 9mm.

 

e.g. Titegroup's published charge weight window for a 147gr FMJ/plated bullet is 3.2gr - 3.6gr. I prepare 10 rounds in 0.2gr or 0.3gr increments with an OAL that I have determined will work in all my handguns. Now I have 10 rounds at 3.2gr, 10 rounds at 3.4gr, and 10 rounds at 3.6gr, all loaded to a length of 1.085 and crimped to .378. I take these to the range and test for functionality and accuracy.  

 

For me, I load everything to fit the gun that has the shortest leade, which are my CZ's. So, even though I could load my bullet to 1.145 for some of my handguns, I load to 1.085 so that my ammo works in everything.

 

Things that can affect recoil are bullet weight, powder choice (as mentioned above by perttime), and charge weight.

Edited July 11 by 4n2t0