Fairly new to reloading and I have come across something that caused a slight problem. I recently changed bullet brands to make my 158 gr .357 cartridges and found the crimp to be past the collar (straight sides) of the bullet. I lengthened the COL slightly, from 1.525 to 1.58, to accommodate the new bullet.

SAAMI shows a COL but I don't see a spec for the bullet itself. So my questions are:
1. Is there a standard for just the bullet?
2. If the bullets can be different lengths, then besides where they sit in the chamber, how can the COL be a determining factor for pressures? I know it affects the pressures, but a general COL would be meaningless.

Thanks,

because there is not one

Welcome to the Forum

You are over thinking the variables

Bullet length and COL have nothing to do with pressure. Case capacity does.

If a given combination of components has a measured pressure of ??? at a stated COL, then pushing that projectile back in the case reduces case volume and increases the pressure of that exact combination of components only.

You have changed projectiles, the pressure figures for your combination of components is no longer a valid number.

Now if your load was not at MAX and you increased case capacity, even with a different projectile, odds are you are still in a safe range.

However, once you have a recipe that you know is in safe pressure range, any time you substitute any component you should reduce the charge and work your way back up to where you were

The OAL of any revolver load, is usually set, so the bullet sets BACK
from the face of the cylinder, to allow functioning.

Some data will give a OAL for a certain bullet but do to shape and
different company dies, it might only work for that one bullet,
even though it is the standard weight for that ammo.

Most bullets seat deeper in a pistol case, the larger the weight of
the bullet but one still needs have the bullet fit properly for its makeup.
One reason a SP or HP design has a different OAL than most RN
bullets of the same weight.
In my 357 cases a 158gr can be from a OAL of 1.58 out to 1.66".

Cartridge overall length is generally set by SAAMI (actually by whoever develops/registers the cartridge with SAAMI) to make sure all cartridges in that caliber won't stick out of the cylinder face and will fit in the magazines of firearms of that caliber.

The others have pretty much discussed the effect of case capacity as affected by bullet seating depth.

"Bullet length and COL have nothing to do with pressure. Case capacity does." So a shorter bullet, set to the same COL, will increase case capacity (combustion volume). I have seen many people tout a specific COL, but it seems to me that would depend on the bullet if you're getting picky.

"In my 357 cases a 158gr can be from a OAL of 1.58 out to 1.66" Isn't the SAAMI max for the 357 at 1.59?

Thanks for the replies. I learned a lot and basically what I was looking for.

Any reputable load data is going to give the COL they used. SAAMI gives a min and max, but part of reloading is to know what a loaded round is supposed to look like. Typically revolver bullets will have a crimp groove or cannelure to crimp into.

.357 Magnum bullets have a large variety of bullet profiles. The critical factor is the amount of bullet in the case. It's best to choose a bullet you have reloading data for rather than choose a bullet and then trying to find reloading data.

1.590" is the industry standard max COL for 357 magnum. Shortest I used was 1.575" using load data out of my Lyman 49th edition manual (or maybe it was my LEE manual). Hornady 9th edition would show all their loads at 1.590". It depends on the load info and the bullet you are using... if you can't find the bullet listed in any printed reloading books then contact the bullet maker to see if they have any load data suggestions.

I have a factory Oregon BC .177 158 Lswc that crimps at 1.62".
A factory Mag-Tec lead round nose can be set at 1.66".

You can seat them deeper if needed but they work in my 686 6"
at these settings for my target loads.

Each bullet may have a different OAL due to where the company
places the crimping area.

For a newer reloader I usually recommend an OAL as designated by the bullet manufacturer for the specific bullet used. This will alleviate any fears of "over pressure from deep seated bullets", and simplify your process and allow you to think about other reloading "facts" or methods to improve your reloading...

BTW I started reloading way pre-web and seated all my revolver bullets to the crimp groove/cannalure and disregarded book OAL (it was rarely the same). Never a problem as I figgered the bullet designer took into consideration how much the bullet protrudes into the case and the remaining capacity. I can't remember any OAL measurement for the 4 revolver cartridges I reload as I never measured any. If they fit in the cylinder I was good to go (not a haphazard method, just a tried and true, safe practice 35+ years old)...