Bullet Length and COL
- Thread starter BondoBob
- Start date
Unless the maker's QC drastically screws up, the cannelure or crimp groove they put on the bullet is going to be in the same place, relative to the base of the bullet, every time. Yes, there are going to be tiny differences, everything has tolerances, but a few ten-thousandths or even a few thousandths difference is not going to matter. It is a measurable amount, but not a significant amount relative to the powder space volume and pressures.
For .38 Special, your COL (or COAL) is to be 1.550" MAX.
You're looking at this slightly skewed. Assume you are seating your bullets so that the mouth of the case is in the middle of the crimp groove (and your cases are uniform length). THe base of the bullet inside the case will be in the same place every time, giving you the same amount of space for the powder, every time. How much of the bullet sticks out past the end of the case, does not affect this.
As long as your round is below the industry standard Max length (1.550" ,38 Special) that amount of the bullet outside the case doesn't matter, it has no effect on powder space, or pressure. (provided its not jammed into the rifling, something not possible with a revolver)
The listed length of a specific bullet load is what it is, it is what the round measured when they seated the bullet to the proper depth. It's a recommendation, (and a good one) but its not a length you MUST match.
Consider this, the book tells you to stay between the inside edges of the while stripe on the road. If you happen to drift to the outside edge of that thin stripe, you're outside the recommended range, but you are not at risk. Run OFF the road, or cross into the other lane, and you are at risk.
There is a considerable margin of safety built into our guns and all the specs involved with them.
Two things
BondoBob,
Lot your precision rifle bullets by weight and length from ogive to the base of bullet.
Another, do a search on the ladder test. Don't just read about the load per MV variation. Read about the SD between seating depth and MV to find your find your ideal CBTO. The chronograph is so important, after you buy another pound of powder and need to adjust your load for the new lot to your ideal MV.
BondoBob,
Lot your precision rifle bullets by weight and length from ogive to the base of bullet.
Another, do a search on the ladder test. Don't just read about the load per MV variation. Read about the SD between seating depth and MV to find your find your ideal CBTO. The chronograph is so important, after you buy another pound of powder and need to adjust your load for the new lot to your ideal MV.
Aguila Blanca
Staff
Have we lost sight of the fact that the question was about loading .38 Special and .357 Magnum handgun ammunition? Does anyone care about the length to the ogive of handgun ammo?
The OP is trying to get started in reloading. Don't make it more complicated than it has to be.
The OP is trying to get started in reloading. Don't make it more complicated than it has to be.
I didn't...heh heh 
Check your brass for uniform length. Adjust your dies so you seat the bullets with the case mouth in the middle of the crimp groove, seat and crimp. Your COAL will be within spec and appropriate.
Its not rocket surgery and its very little brain science, you don't need to overthink it, and you certainly don't need to worry about what match rifle shooters do with their precision ammo.
"racewinning" tips about adjusting your formula 1 Indy care aren't much use when you drive a pickup truck.
Check your brass for uniform length. Adjust your dies so you seat the bullets with the case mouth in the middle of the crimp groove, seat and crimp. Your COAL will be within spec and appropriate.
Its not rocket surgery and its very little brain science, you don't need to overthink it, and you certainly don't need to worry about what match rifle shooters do with their precision ammo.
"racewinning" tips about adjusting your formula 1 Indy care aren't much use when you drive a pickup truck.
If you are talking about going from one similar weight roundnose to another then no it will not change much.
Just speaking for my pistol seating dies but all have a stem ending in a very slight concave surface. It's not quite flat. When you raise that ram as high as it will go the distance from the shell holder to the seating stem will always be the same. It really does not care whose brand bullet is being seated or whose brand bullet is being seated. The COL might change slightly when going from a round nose to a wad cutter becasue of the concave shape of the seating stem but that's about it. There may be a tad more bullet in the case depending on the difference in the ogives shape . But I don't think the radius will differ that much from one round nose to another.
Just speaking for my pistol seating dies but all have a stem ending in a very slight concave surface. It's not quite flat. When you raise that ram as high as it will go the distance from the shell holder to the seating stem will always be the same. It really does not care whose brand bullet is being seated or whose brand bullet is being seated. The COL might change slightly when going from a round nose to a wad cutter becasue of the concave shape of the seating stem but that's about it. There may be a tad more bullet in the case depending on the difference in the ogives shape . But I don't think the radius will differ that much from one round nose to another.
Bob,
You can almost always assume the cannelure is in the right place if the bullet is designed for the cartridge you are reloading. With revolver cartridges, this is easy to check: You put a fired case into your cylinder and measure the length of the cylinder from the cylinder face to the bottom of the case. If your COL is shorter than that, assuming you've provided enough crimp for the case to hang onto the bullet during recoil and not let that experience start inertially pulling it out, then the cartridge won't jam the revolver.
Where peak pressure is concerned, bullet jump to the lands is a non-issue in revolvers. Unlike a rifle cartridge, which has much of the bullet ogive already past the throat of the rifling when it fires, leaving the shoulder of the bullet very little distance to travel to arrive at the throat, a revolver bullet always has the whole length of the bullet ogive to travel plus the barrel/cylinder gap plus the length of most of the forcing cone to travel before meeting the throat. That's lots of jump and won't raise pressure in any way.
As to how seating the bullet does affect pressure, that depends on how much space there is in the case and under the bullet for the powder to start burning in. If you have two bullets of similar similar shape and similar hardness (usually identified by them having similar construction method), then you can get pressure to match well by giving both bullets the same seating depth, even if they aren't exactly the same length.
As a practical matter, seating depth is measured as the length of the portion of a bullet that is seated below the case mouth.
Seating Depth = Case Length + Bullet Length - COL
Case Length, as used in that calculation may be either the maximum case length or the nominal trim-to case length, whichever you prefer as long as you use it consistently.
Once you have the seating depth of the original load using the original bullet's length, you can find the COL for a bullet of different length by rearranging the same formula to:
COL = Case Length + Bullet Length - Seating Depth (found for original bullet)
COL: stands for Cartridge Overall Length. Before the 1950s there were two spellings of overall. One is the compound word, first used by Chaucer, which means "taken altogether". The second spelling was hyphenated over-all, and was used for the total physical length of a boat or arrow or whatever. Since the 1950s, the hyphen form has been dropped. COL stands for the modern spelling, Cartridge Overall Length, while COAL stands for the obsolete spelling, Cartridge Over-All Length.
You can almost always assume the cannelure is in the right place if the bullet is designed for the cartridge you are reloading. With revolver cartridges, this is easy to check: You put a fired case into your cylinder and measure the length of the cylinder from the cylinder face to the bottom of the case. If your COL is shorter than that, assuming you've provided enough crimp for the case to hang onto the bullet during recoil and not let that experience start inertially pulling it out, then the cartridge won't jam the revolver.
Where peak pressure is concerned, bullet jump to the lands is a non-issue in revolvers. Unlike a rifle cartridge, which has much of the bullet ogive already past the throat of the rifling when it fires, leaving the shoulder of the bullet very little distance to travel to arrive at the throat, a revolver bullet always has the whole length of the bullet ogive to travel plus the barrel/cylinder gap plus the length of most of the forcing cone to travel before meeting the throat. That's lots of jump and won't raise pressure in any way.
As to how seating the bullet does affect pressure, that depends on how much space there is in the case and under the bullet for the powder to start burning in. If you have two bullets of similar similar shape and similar hardness (usually identified by them having similar construction method), then you can get pressure to match well by giving both bullets the same seating depth, even if they aren't exactly the same length.
SAAMI Glossary said:
As a practical matter, seating depth is measured as the length of the portion of a bullet that is seated below the case mouth.
Seating Depth = Case Length + Bullet Length - COL
Case Length, as used in that calculation may be either the maximum case length or the nominal trim-to case length, whichever you prefer as long as you use it consistently.
Once you have the seating depth of the original load using the original bullet's length, you can find the COL for a bullet of different length by rearranging the same formula to:
COL = Case Length + Bullet Length - Seating Depth (found for original bullet)
COL: stands for Cartridge Overall Length. Before the 1950s there were two spellings of overall. One is the compound word, first used by Chaucer, which means "taken altogether". The second spelling was hyphenated over-all, and was used for the total physical length of a boat or arrow or whatever. Since the 1950s, the hyphen form has been dropped. COL stands for the modern spelling, Cartridge Overall Length, while COAL stands for the obsolete spelling, Cartridge Over-All Length.
Well, do you load 38 Spec/357 Mag with them? If so, then you must be using something that I am not familiar with as far as jacketed handgun bullets.
As to the OP's question, he was asking specifically about those two using jacketed and lead bullets. I don't think I have ever noticed a bullet designed for the 38 Spec/357 Mag that doesn't have a cannelure.