That extra crimp that some cartridges have and some don't, what is it?

Stopsign32v · #1 08-24-2017, 05:34 PM

This has been bugging me for I don't know how long. What in the world is that extra line for and what causes it?

Examples:

Middle cartridge

Right cartridge

mikld · #2 08-24-2017, 05:48 PM

Called a "canalure", used to prevent bullet set back. Used almost as long as metal cartridge cases, 1870s (?)...

Stopsign32v · #3 08-24-2017, 08:53 PM

Why would you have Bullet setback in the 1800s? Or Bullet setback in a revolver?

I thought Bullet setback was due to semi autos and multiple chamberings of a round without firing it. On top of that what would be the big deal of Bullet setback in a black powder situation?

MichiganScott · #4 08-24-2017, 09:06 PM

Quote:

Originally Posted by Stopsign32v

Why would you have Bullet setback in the 1800s? Or Bullet setback in a revolver?

I thought Bullet setback was due to semi autos and multiple chamberings of a round without firing it. On top of that what would be the big deal of Bullet setback in a black powder situation?

Bigger kaboom!

Actually black powder or spacer wads should fill the case to the base of the bullet. If the bullet is forcibly set back into the case it can cause the black powder to explode like the roll caps we used to use as kids.

fredj338 · #5 08-24-2017, 10:38 PM

Quote:

Originally Posted by Stopsign32v

Why would you have Bullet setback in the 1800s? Or Bullet setback in a revolver?

I thought Bullet setback was due to semi autos and multiple chamberings of a round without firing it. On top of that what would be the big deal of Bullet setback in a black powder situation?

Lever actionrifles are notorious for bullet setback from the tubular mags. The major reason the mid case canelure came about. Revolovers back then, not an issue.

fredj338 · #6 08-24-2017, 10:42 PM

Quote:

Originally Posted by MichiganScott

Bigger kaboom!

Actually black powder or spacer wads should fill the case to the base of the bullet. If the bullet is forcibly set back into the case it can cause the black powder to explode like the roll caps we used to use as kids.

I doubt that ever happened. The force needed would be like a hammer blow, a big hammer blow. Besides, most BP loads are already compressed 100%.

MichiganScott · #7 08-25-2017, 09:59 AM

Quote:

Originally Posted by fredj338

I doubt that ever happened. The force needed would be like a hammer blow, a big hammer blow. Besides, most BP loads are already compressed 100%.

You are probably correct about the cartridge usage in tubular magazine rifles. I personally saw a muzzle loading rifle charge go off once when the shooter was seating a bullet with a hammer and a range rod. You may notice I used the term "forcibly".

Please explain what you mean by 100% compressed. Do you mean compressed into a solid mass or simply the case is filled 100%? Slight compression is required for the most consistent ignition in black powder cartridges.

fredj338 · #8 08-25-2017, 11:26 AM

Quote:

Originally Posted by MichiganScott

You are probably correct about the cartridge usage in tubular magazine rifles. I personally saw a muzzle loading rifle charge go off once when the shooter was seating a bullet with a hammer and a range rod. You may notice I used the term "forcibly".

Please explain what you mean by 100% compressed. Do you mean compressed into a solid mass or simply the case is filled 100%? Slight compression is required for the most consistent ignition in black powder cartridges.

Same thing really. 100% comPression means full case with bullet holding powder in place. Then there is 105%, etc.

VThillman · #9 08-25-2017, 01:23 PM

Except in tube magazines, where cartridges get thumped by rounds ahead of them in the tube, the phenomenon is reported to be in the other direction; inertia moves bullets forward in their cases during recoil.

oneounceload · #10 08-25-2017, 01:25 PM

cannelure (the correct spelling):

Cannelure - Wikipedia

fredj338 · #11 08-25-2017, 02:15 PM

Quote:

Originally Posted by VThillman

Except in tube magazines, where cartridges get thumped by rounds ahead of them in the tube, the phenomenon is reported to be in the other direction; inertia moves bullets forward in their cases during recoil.

Not really, recoil pounds the case head against the bullet & you get setback. I had a heck of a time with my 44-40 in a Henry when I first got it. Never had a round go too long, but plenty setback.

mikld · #12 08-25-2017, 02:17 PM

Having not been around and shooting in the late 1800s, I cannot say how the ammo was handled, but all you have to do is google "cartridges of the late 19th century" and look and see the canalures. Tubular magazines and pressure changes along with feeding issues (many rifles in 1870s were not "hand fed" and weren't semi-autos) would be reasons for the use of case canalures...

VThillman · #13 08-25-2017, 02:19 PM

Quote:

Originally Posted by fredj338

Not really, recoil pounds the case head against the bullet & you get setback. I had a heck of a time with my 44-40 in a Henry when I first got it. Never had a round go too long, but plenty setback.

Um, tube magazine, eh?