Bullet Length and COL

[BondoBob]

Are all bullets of a given grain weight going to be the same length? I mean if I buy 125gr 38/357 bullets from different brands, and use a powder that does not have specific load data for that bullet type (ie; 125 FMJ vs 125 LRN) can i assume overall cartridge length will always be the same? Or will the bullet's manufacturers have data on their packaging specifying their COL?

[Unclenick]

Not at all. A flat nose bullet will be shorter than a round nose or a pointed boattail. A solid copper or brass or bronze bullet will be longer than a lead core bullet with the same nose and tail shapes because copper and brass and bronze are all less dense than lead. A tungsten-filled bullet will be shorter because tungsten is more dense than lead.

This article shows pressure among same-weight bullets all loaded with the same powder charge can vary 30% because of the shape and density and hardness differences among the different bullet construction types.

Regarding your particular question about jacketed vs. lead: lead bullets, having softer exteriors, cannot be loaded to pressures as high as jacketed bullet can without some distortion occurring in the base or without lead stripping off the bullets in the barrel, both of which deteriorate gun accuracy. An accumulation of too much lead or copper will raise pressures as subsequent bullets have to squeeze through the constriction that creates. It is always best to look up load data for the particular bullet type you are loading. Get a manual from Hornady or Sierra or any of the other bullet makers and you will normally find the give you the COL they used in testing each individual bullet with the load given. The Lyman manual has both jacketed and lead in multiple weights and is a good source of comparison.

A general rule in handloading is, if you use any component combination that is different from the combination in a published load recipe, you need to reduce the charge weight to 10% below the maximum charge listed and work it up in charge weight increments of not more than 2% of the maximum charge weight listed while watching for signs of excess pressure. The exceptions are the primer or a change in the particular lot of powder you have purchased, which are changes that normally only merit a 5% reduction. Also, if you got a high-pressure sign during any workup, you stop increasing the loads and you reduce the charge that is giving you the pressure sign by 5%.

If you haven't run into these sorts of rules before, you need to buy and read a good reloading manual or book of reloading practices. The Lyman manuals provide some general information and the ABC's of reloading provides good general instruction on handloading.

[44 AMP]

Also, you need to be aware that there are two COAL measurements.

The first is the industry standard, (SAAMI) which is the max length of the loaded round (measured case base to bullet tip), and is intended to work in every firearm of that caliber.

The second COAL length is what the round you loaded actually measures. Normally, it will be at or slightly below the SAAMI spec.

It might be considerably below the SAAMI spec. There's nothing wrong with that. The SAAMI COAL is a number you should not exceed, it s NOT a number you have to match or load to.

The SAAMI number is listed in the books, its the max length of the loaded cartridge. When a specific load is listed with a COAL, its the length they got, of the round they loaded. It MAY be a significant factor in that specific load, or it MAY just be the length things turned out at.

You'll need to take other factors into consideration to know which it is.

[BondoBob]

Glad I asked. I suspected they'd all be a bit different. I have ordered JHP 125 from Speer #4013 to start. Not finding any information on COAL for that one online, and I'm disappointed that my Lee manual leaves out the case length data. I have the ABC of reloading on the way to me. Maybe I'll get the Lyman manual and call Speer unless someone can direct me to the info online.

Thanks.

[higgite]

Be aware that in addition to different bullets styles (flat point, round nose, etc.) being different lengths, even the same style bullet from different vendors will usually be different lengths due to bullet profile. For instance, I have some 124gr RN plated from X-Treme that averaged .589" long and some from RMR that averaged .583" long. That's why you should plunk test a new recipe in the barrel(s) that it will be shot from.

[44 AMP]

and I'm disappointed that my Lee manual leaves out the case length data.

Do you mean case length or Cartridge Over All Loaded (COAL) length?

First off, don't overthink things. Bullets from the same box can vary a few thousandths in length.

If you are loading any kind of pointed bullet, the seating stem doesn't contact the bullet tip, so a small difference in the length of the tip is insignificant.

The two points that are "fixed" are the length that works all the way through your magazine and feeds into the chamber, and the length that does not contact the rifling. If your round does both of these, you're good on length.

The degree of precision demanded to shoot tiny little groups at 600m is largely wasted on pistols and on rifles that can't take advantage of it.

[Dufus]

Most times when using jacketed handgun bullets, just seat to the cannelure and don't worry too much about the COAL measurement.

[74A95]

Originally Posted by BondoBob

I have ordered JHP 125 from Speer #4013 to start. Not finding any information on COAL for that one online. Maybe I'll get the Lyman manual and call Speer unless someone can direct me to the info online.

Thanks.

See here: https://www.speer.com/reloading/handgun-data.html

[BondoBob]

Ok, I'm not going to sweat this too much. The bullet's I've ordered do have a cannelure. And I'm starting with 38 spl in a 357 revolver. So no worries about feeding or the plunk test. My concern was more about over or under pressuring the round by not having the correct COAL. It sounds like this really isn't a critical spec for what I'm doing. I saw a Lyman manual for $8 that is focused on 38, 357 and 44mag which covers all the rounds I'll be loading in the future. So, Thanks again to everyone, really appreciate the ongoing support as I start this.

[Aguila Blanca]

Originally Posted by Dufus

Most times when using jacketed handgun bullets, just seat to the cannelure and don't worry too much about the COAL measurement.

I must have eight different brands/calibers/weights of handgun bullets on my shelves (maybe even a couple more than that), and not one of them has a cannelure.

[BJung]

Overall Length this the measure of the cartridge from the end of the pullet to the base of the cartridge. COL is the distance from where the bullet ogive touches the rifling to the base of the case. Pistol ammo is usually measured in OAL.

Since you are buying 125gr bullets, am I assuming that you are reloading for a handgun? If so, this is my experience. I loaded .45acp test loads where the OAL just fit in the magazine at 1.272". The second test loads used published OAL at 1.250". My groups with a longer OAL was 1" at 20 yds vs 3". I don't know about revolvers. If I were to crimp, my preference would be the LEE Factory crimp die. the crimp isn't curled or rolled. Instead, the rim of he case moth is flattened.

For semi-auto rifles, I'm not sure. I haven't made test loads for my sks yet. The chamber might be longer than the magazine. At most, I would go with OAL like my semi-auto handgun.

If you have a bolt-action rifle, COL is very important for accuracy, atleast to me.

[44 AMP]

Overall Length this the measure of the cartridge from the end of the pullet to the base of the cartridge.

CARTRIDGE Over-all Length (expressed as COL for generations, and more recently as COAL is the length of the loaded round (with bullet) from the base of the case to the tip of the bullet.

COL is the distance from where the bullet ogive touches the rifling to the base of the case.

Use of COL as you describe it is not familiar to me. Where are you getting that COL = case base to bullet ogive?

Measuring to the point where the bullet ogive contacts the rifling is a measurement that is useful only for a specific bullet and barrel. It does not apply the same "across the board".

We have discussed this before, more than once I think, and as far as I know, there is no "standard" term or abbreviation for the base to ogive distance, and using COL is confusing as many if not most of us will think either case overall length or cartridge over all length, and not some point on the bullet ogive which will be a different length with each different profile bullet and each gun barrel.

My concern was more about over or under pressuring the round by not having the correct COAL.

For what you're doing, its not a concern. A few thousandths difference in the seating depth shouldn't make a difference unless you're working with absolute maximum level loads. A few thousandths difference In overall length (with the bullet bases in the same place due to seating to the cannelure) makes no difference at all.

[74A95]

Originally Posted by burbank_jung

Overall Length this the measure of the cartridge from the end of the pullet to the base of the cartridge. COL is the distance from where the bullet ogive touches the rifling to the base of the case.

I've not seen COL used to refer to comparator overall length.

I've only seen COL refer to cartridge overall length. Hornady uses COL to refer to cartridge overall length.

Your non-standard use of COL will likely only confuse people.

[BJung]

I stand corrected. I need to review my definition of terms.

Thank you guys

[BJung]

Guys, I looked it up and learned a new word.

The term I meant was CBTO. I misused the acronym COAL to mean this and never saw the other acronym come up.

[RaySendero]

BondoBob wrote:
Glad I asked. I suspected they'd all be a bit different. I have ordered JHP 125 from Speer #4013 to start. Not finding any information on COAL for that one online, and I'm disappointed that my Lee manual leaves out the case length data. I have the ABC of reloading on the way to me. Maybe I'll get the Lyman manual and call Speer unless someone can direct me to the info online.

Bob, Did you notice that Speer lists the length of that #4013 as 0.525"/13.34mm.

[Bart B.]

From SAAMI's glossary for the term "overall length:"

"Ammunition: The greatest dimension of a loaded cartridge, i.e., from face of the head to the tip of the bullet for centerfire or rimfire or to the crimp for shotshells or blanks (not to be confused with the uncrimped length in a shotshell."

Is there any standard bullet reference diameter for each cartridge base to ogive measuring? There's a wide range of bullet and chamber throat dimensions for each one. It better not be smaller than bore diameter.

[BondoBob]

Ray, I did see that. My concern was that the position of the cannelure (if there is one) could vary and affect COL. I'm just going to avoid plated bullets and those with no cannelure at least for now.

Since posting I've found a couple sources the COL is to be 1.445 for the powder I'm going to use. The range was 1.437 to 1.447.

[rclark]

One thing I never worried about since I started reloading back in the early 80s, is OAL in revolver cartridges. Just crimp into the given crimp groove (lead or jacketed) and you'll be fine. It wasn't until a few years ago that I broke down and got a caliper when I started loading .45 ACP and 9mm. Ie. bullets that have no crimp groove and short stubby cases.

Subject of different bullets, but same weight. What matters is how deeply they are seated (volume under the bullet). The deeper they are, the more pressure will be created for a given powder charge. However if the bullets are 'approx' the same by eye-balling them (different manufactures), you'll be fine. Plus if you are loading 'light/medium', the little bit of pressure difference isn't going to matter a hill of beans in .357 or .44Mag. Where you 'really' have to be careful is loading at the bleeding edge, or short stubby cases like 9mm or .45 ACP where there really isn't much 'wiggle' room for volume.

My two and a half cents!

[BondoBob]

Guys, I looked it up and learned a new word.

The term I meant was CBTO. I misused the acronym COAL to mean this and never saw the other acronym come up.

Burbank; This article was interesting. I'll come back to it if/when I ever start loading for 243 or 6.5 creedmoor.

http://bulletin.accurateshooter.com/...s-to-consider/

[BJung]

Making very nice pistol reloads do seem like a waste of time because of the primary component that throws the bullet off, namely "ME".

[44 AMP]

Ray, I did see that. My concern was that the position of the cannelure (if there is one) could vary and affect COL.....

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.

Since posting I've found a couple sources the COL is to be 1.445 for the powder I'm going to use. The range was 1.437 to 1.447.

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.

[BJung]

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]

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.

[BJung]

Sorry, I got carried away.

heheh