.38 special bullets, same weight, very different cannelue.

[m-man]

I have these 2 types of .38 bullets, both 125gr, and both JHP, so the powder charge listings are the same as well
But one the cannelure is significantly lower on one than the other,
seated it is 1.54 which is still under the max col of 1.550, the other seats at 1.43.
I was concerned about the difference in case volume between each of these bullets being a problem,
It seems like the manufacturer puts the cannelure where they want it to be set -- but why does it vary so much?

[tabascoz28]

Maybe it was on sale. I would ignore it and load to safe depth and monitor for signs of over pressure. I believe the crimp is what does the work, the cannelure is just a reference point for me.

[tabascoz28]

Also the first one might make a .38 revolver jam up. The bullet profiles also look different, shape of ogive.

[smoothy8500]

Isn't max COAL around 1.440 to 1.550"?

[Cowboy T]

Maybe it was on sale. I would ignore it and load to safe depth and monitor for signs of over pressure. I believe the crimp is what does the work, the cannelure is just a reference point for me.

Agreed. I'm not sure why that cannelure is so far back on that bullet, but it's wrong. The proper place for it is closer to the where the ogive starts. Just load it to max OAL, and you should be fine.

BTW...are you shooting these in a levergun, perchance, or is this revolver-only?

[kcstott]

I have these 2 types of .38 bullets, both 125gr, and both JHP, so the powder charge listings are the same as well
But one the cannelure is significantly lower on one than the other,
seated it is 1.54 which is still under the max col of 1.550, the other seats at 1.43.
I was concerned about the difference in case volume between each of these bullets being a problem,
It seems like the manufacturer puts the cannelure where they want it to be set -- but why does it vary so much?

Cannelures are not crimp grooves. They are meant to help lock the jacket to the core. They help on a crimp but are not necessary.
Seat as usual and stop all this non sense.

[Che762x39]

I have these 2 types of .38 bullets, both 125gr, and both JHP, so the powder charge listings are the same as well ...

What brands are they? Asking for a friend.

[Flouncer]

Cannelures are not crimp grooves. They are meant to help lock the jacket to the core. They help on a crimp but are not necessary.
Seat as usual and stop all this non sense.

From the first two reloading manuals I pulled off my shelf:

Speer Number 12- " Circumirfential groove (s) around a bullet or cartridge case. Used for identification, to hold lubricant or to crimp case into. "

Hornady 10th edition - " An identification, crimping or lubricant groove on a bullet. "

from Speer page 396 on the 44 Magnum Rifle cartridge and the 200 and 300 grain bullets

". . . . . . a frim crimp are critical to reliable function. "

and,

page 397 - " The 300 grain bullet has two cannelures for crimping . .. ."

"This sets the proper overall cartridge length for reliable functioning in repeating rifles "

Mentioned in both of these Industry sources is the fact that the cannelure is used to hold the seated bullet from recoil. Nowhere is it mentioned that they are used to lock the core to the jacket. I think you have transposed the methodology from the Hornady or Remington Core Lokt but that is just a guess as I am not familiar with those brands of projectiles.