Probably a stupid question

[balderclev]

Been reloading some military LC brass. Have to size, trim, and remove crimp of course.

My question is that, after shooting them and then resizing them again, I am under the COL and do not want to trim again. But doesn't this seat the bullets more in the case? I know the cartridge will chamber fine but am I getting more pressure than the first firing with all else the same?

[Jimro]

The bullet seats in your seating die based on the distance from the shell holder to where the seating plug stops.

Trimming the neck has nothing to do with Collective Overall Length, it just ensures that the neck doesn't grow too long and get pinched into the leade causing unsafe pressures.

Jimro

[balderclev]

Yes, I understand that the COL will be the same, but with the case being longer, the bullet will be seated deeper based on the increased length from the shell holder to the original seating depth. Doesn't this increase pressures? Am I confused about something?

[dmazur]

After resizing (assuming FL resizing), the neck is pushed forward as the die "reworks" the brass near the shoulder, making the case length longer.

The important dimension for maximizing case life and minimizing headspace separation odds is the head to shoulder distance, sometimes referred to as "cartridge headspace".

Resizing sets this back to factory, or back to a couple thousandths under fired length, depending on what you use as a reference and how you set your resizing die.

If it got longer to the shoulder, it wouldn't chamber.

In general, if you are trimming you are probably working with a bottleneck cartridge (.308 maybe?). Pressures aren't as sensitive to a slight change in seating depth as the change in volume is relatively small, compared to the total case volume.

Pistol cases are something completely different. Setback due to improper tension can cause dramatic increases in pressure for a relatively small amount of setback. But the 9mm case (for example) doesn't have much volume to start with.

I think the only thing you may be confused about is which part of the case gets longer as a result of resizing. It isn't the whole case - just the neck.

[Dave P]

Oh boy.

"but with the case being longer, the bullet will be seated deeper "

No. Measure from the base of the bullet to the case head: no matter how long the case neck is, the usable volume of the case is the same. You will see less of the bullet exposed , but case volume is the same.

"Collective Overall Length" Jimro, I sure hope that is your spell checker choking. Never heard of it. I have heard cartridge OAL (COAL) but I am sure that is a redundant term with OAL.

[Jimro]

Dave P,

I've seen it COL, OAL, and COAL.

Just google "Collective overall length" with the quotes (causes a phrase match search) and you'll see it too.

Jimro

[dmazur]

Just google "Collective overall length"...

All that a search does is confirm that many people have used that term. It doesn't validate the usage.

One of the hits was for containers -

Sea Cell 20

...A container of any preceding claim, longer than a nominal ISO 20' span or actual 19ft10V_in overall outer length limit, with at least part of the extended container length occupying former free space between two 20' ISO series 1 C standard containers when placed end to end in tandem, such that their cumulative or collective overall length is some 40ft, but with reduced wasted intervening space in favour of increased usable load capacity...

So, I would agree that the "C" can stand for almost anything, but in reloading I believe the "best" interpretation is cartridge. After all, we're not describing the summed length of components lined up. We're describing the length of an assembled cartridge, which involves seating depth.

As an aside, in researching this, I found a thread which described the difference between COL and COAL as -

COL = Cartridge Overall Length
COAL = black mineral commonly mined and used as a fuel

[Jimro]

dmazur,

Doesn't make it wrong. Collective overall length is here to stay, and in the realm of small arms makes just as much sense as Cartridge Overall Length when dealing with the total length of a round of ammunition. After all Cartridge Overall Length can refer to those thingummies that go in printers.

Jimro

[balderclev]

Wow, this thread is having a "Webster's" moment concerning cartridge overall length. lol

Anyway, dmazur has cleared up my confusion on that subject.

Now a different question...I am loading Hornady 55gr SP with cannelure. I am seating them at the cannelure. Is it a problem if I seat them above the cannelure so as to increase the COL?

[dmazur]

Well, I won't expend a lot of time arguing the point. It's a free country. (Well, except for a few states...)

From the Sierra Reloading Manual (5th Ed.) -

OAL: Over All Length: The total length of a loaded cartridge. May also be listed as LOA (Length Over All), or COL (Cartridge Overall Length).

However, even dictionaries "cave" to common use and legitimize slang and defacto synonyms.

And this forum is already afflicted with posts which are absolutely devoid of capital letters and punctuation.

So, you are probably right.

[dmazur]

Is it a problem if I seat them above the cannelure so as to increase the COL?

If you mean "so the cannelure is showing", then the concern is threefold -

1. The cartridge has to fit in the magazine and feed and chamber correctly.
2. The cartridge can't be so long that the bullet is jammed into the rifling, which will create dangerous overpressure.
3. There has to be enough bullet left in the neck to retain it for the intended conditions.

The dangerous overpressure is created by the complete lack of "jump", not by an actual overcharge. My understanding is that typical reloading manuals assume you are not doing this. What benchresters do isn't typical.

As to the seating depth in the neck, I have read that one bullet diameter is sometimes considered a minimum. However, target shooters loading singly aren't as concerned about this as someone who intends to feed cartridges from a magazine.

[balderclev]

dmazur, My concern was that if the cannelure is showing when seated but the COL is still below maximum, is the cartridge considered safe. I am not going beyond the COL as yet. I may when I have enough experience to actually measure the lands and build loads for a particular rifle

[Jimro]

55gr bullet with a cannelure.... I would bet that you won't see much of a gain in accuracy by playing with seating depth. You'll see a much bigger accuracy gain by going to a match bullet.

Jimro

[Brian Pfleuger]

Originally Posted by balderclev

dmazur, My concern was that if the cannelure is showing when seated but the COL is still below maximum, is the cartridge considered safe. I am not going beyond the COL as yet. I may when I have enough experience to actually measure the lands and build loads for a particular rifle

COL listed in books is irrelevant for rifle rounds. Some books don't even list it and I wish none of them did.

The cannelure is irrelevant.

Load the round so it fits and functions in your gun, start at starting loads and work up.

The length of the case doesn't effect pressure you're seating the bullet the same. The space under it in the case is the same.

[dmazur]

There are quite a few threads about not crimping if there isn't a cannelure. You risk damaging the bullet, and there isn't any "return" for this risk.

So, if you are going to seat with the cannelure showing, I would delete the crimp step, if you were crimping into the cannelure when it was at that deeper depth setting.

The general concerns for bottleneck rifle cartridges are covered thoroughly in most reloading manuals. I believe these would include -

1. Work up load from minimum. Don't pick "1 gr under max" or "middle" or something. The barrel used for testing isn't your barrel and you may experience higher pressure than their lab did.

2. Seat primers at or below flush. High primers can prevent proper chambering or can go off on bolt clousure.

3. Trim cases to recommended "trim-to" length when repeated resizing makes their length reach the maximum. Case mouths crimped by the rifling will cause dangerous overpressure.

4. Resize cases to slightly under fired length for your rifle, or to SAAMI spec if you are reloading and expect the round to chamber in several rifles. Use a case headspace gauge to set up your resizing die. Induced excessive headspace can cause case head separation, which is dangerous.

5. Seat bullets to keep them out of the rifling. The published COL for that bullet is a guideline and will not necessarily keep a bullet with a different profile out of the rifling, even though the caliber is the same. The ogive is the control point.

More on COL -

If you have found a "general" COL spec, such as might appear in the cartridge drawing, this should be taken as a guideline, as mentioned in another reply. It is usually a magazine length restriction. The Sierra Reloading Manual labels their cartridge drawings "x.xxx MAXIMUM". Then, for each bullet listed for that cartridge, there are different COL's shown (And Sierra uses the term C.O.A.L. for this...same thing as COL.)

For example (using .308 Winchester), the stubby 110gr RN has a COL of 2.500", the 150gr FMJBT has a COL of 2.775" and the 190gr HPBT has a COL of 2.800". The drawing shows 2.810" as maximum COL, and all of these are under maximum.

Why can't the 110gr bullet be seated to 2.775" COL like the 150gr FMJBT? The ogive will probably hit the lands.

As further proof of this, you could examine the COL's for bullets of the same weight, but with different profiles -

180gr HPBT MatchKing shows COL of 2.800"
180gr RN shows COL of 2.710"

Will a bullet seated to some arbitrary depth hit your lands and cause dangerous overpressure? Only measurement on your particular rifle can answer that question, as manufacturers don't appear to follow any particular standards for where the rifling starts. (I read of one which was supposed to have deliberately created a "long chamber" in an attempt to reduce liability.)

Sorry for the long answer, but

...if the cannelure is showing when seated but the COL is still below maximum, is the cartridge considered safe.

isn't an easy question. As you are ignoring the COL for that bullet, you may have moved the ogive enough to get into trouble.

I am not going beyond the COL as yet. I may when I have enough experience to actually measure the lands and build loads for a particular rifle.

Well, by seating longer than the cannelure, you are going beyond the COL. For that bullet. Whether this is successful (or safe) can't be stated without measurements.

As an aside, some reloading data with long for caliber (VLD) bullets has COL which is quite a bit longer than the standard cartridge drawing COL. And these cartridges have to be singly loaded as they won't fit in a magazine. For special single-shot bolt action rifles, this isn't a concern. (The folks who have these rifles have them built without a magazine well, so the stock is stiffer...and their data isn't universally applicable.)

Read the guidelines in the reloading manuals. Following published data includes following the recommended seating depth, unless you have measurements which show you can seat longer for a particular rifle...

[Edward429451]

55gr bullet with a cannelure.... I would bet that you won't see much of a gain in accuracy by playing with seating depth. You'll see a much bigger accuracy gain by going to a match bullet.

I have found this to be true. Match bullets get you accuracy more/faster than any other experimentation. Match bullets are very consistent in weight, and construction. The poor mans match bullet is to weigh and segregate according to weight, ans separate batches for use. The heavy and light bullet batches can be loaded for range use, given to friends to shoot (LOL) up while you keep the better batches. Especially when there's ten bucks in the coffee can for the impromptu friendly contest with friends at the range, lol.

Work up load from minimum. Don't pick "1 gr under max" or "middle" or something. The barrel used for testing isn't your barrel and you may experience higher pressure than their lab did.

Best listen to this man, he knows of what he speaks. It can be downright dangerous to reduce a max load for a starting point. You might get away with it for awhile but it only takes one over pressure round to wreck a gun. What do think "Starting loads" are for, anyway?

[balderclev]

Thanks for the insights everyone.

I am not crimping the bullets at the moment. I am well under the COL for that bullet, however I have not measured where the rifling starts.

What i was thinking about was seating the bullet out further to get closer to the COL. From what i am hearing here, I should just keep seating the bullet to the cannelure until I know exactly where the lands are on my rifle.

[dmazur]

You don't need a bunch of expensive gauges to determine where the lands are. There are techniques which require nothing more than a dowel and a razor blade.

It's buried in here, somewhere -

http://thefiringline.com/forums/showthread.php?t=521336

In my long-winded answer, I may not have emphasized that Sierra may clearly show the difference between a cartridge maximum length (shown in the drawing at the start of the section for that caliber) and what they term C.O.A.L. for a particular bullet, but other reloading manuals may not make this distinction.

One is an aid so that you don't create a cartridge that won't fit a standard box magazine.

The other is an aid so that you don't seat a bullet too long and get its ogive in the lands.

Good luck. Reloading can be a lot of fun, even if it does have hundreds of details...

[Idaho Spud]

Collective overall length is the term they used in the USSR, I believe.

[Brian Pfleuger]

The esoterica can be truly astounding, sometimes.

COL
COAL
OAL

All mean the same thing. It is the context that defines if you are referring to the measurement at the ogive or at the tip.

The least "correct" current terms, linguistically, would be COAL and OAL because they imply that "overall" is either hyphenated or two words, neither of which is typically true anymore.

We should probably be using OL or COL, from a linguistics standpoint. However, OAL seems to have become the new norm, most folks simply dropping the "C" since the context indicates that we're referring to a cartridge.

For what it's worth, I have never heard of "Collective Over All Length" until this thread.

[wncchester]

"Doesn't (seating deeper) increase pressures? Am I confused about something?"

You're confused. Probably from reading posts by web gurus who don't know what applies to high pressure/small case autoloader ammo does NOT translate across the board, and especially not so for rifle ammo. Rifles have much larger combustion chambers and use much slower burning powders than 9-10mm/.40 auto loaders so seating deeper in rifles within reason (and other hangun cartridges too) actually reduces chamber pressure for a given load.

Bullet canalures have no special significance unless you want to crimp in them. And case trim length is irrelivant to OAL.

I don't know what you're calling min/max for a OAL/COAL but if you mean the book numbers, all that amounts to is the length the book test team used to develop the listed data in their rifle. Your rifle is not their's so their OAL is no more a "law" for you than their powder charges. Pick an OAL 15-20 thou (or more) off the lands and develop your charge normally, then tweak OAL for best accuracy as a final step.

I've been doing this stuff for nearing 50 years but "collective overall length" is a new distortion of the language. Just shows the inventiveness of the iggerant trying to sound like an old hand I suppose.

[balderclev]

Learning a lot here. Hoping most of it will soak in with time and experience.

I think I've got the 223 reloading going well. 3/4" groups at a hundred. Want to get them to 1/2" so I guess the next step is to measure the OAL of my rifle.

38 special reloads are doing well. Not an expert with pistols anyway so just wanted something light to shoot.

Getting ready to load 40 S&W this evening. Really different. Slight bulge at the head I assume it didn't resize. Moved it down but could never get rid of it. Slight bulge where the bullet (140 gr lead TC) is seated. Inserted some into my Beretta and about the same as factory FMJ. Haven't charged any cases yet until I am comfortable about a starting load with 700X which is the only pistol powder I have.

[Nathan]

OAL tip to base is included in manuals to say this max load with this bullet was seated to this OAL when pressure was recorded. Looking at OAL alone, yes, it increases some as you shorten the OAL.

If you increase OAL until the lands are touched, that too increases pressure some.

Some is my way of saying 10 - 25% from what I read. Does it matter? Depends on rifle and load.

If you want to touch the lands, I never touch..., but sometimes shoot into +0.010" or shoot close to -0.010" to get best accuracy. I work up the load twice to determine OAL. First min load at many OAL, then best OAL and vary charge.

You can set OAL however you want, but I use the Hornady tools.

Benchrest is different because their actions and barrels can take case splitting pressure without much flex in the gun.

[Edward429451]

I think I've got the 223 reloading going well. 3/4" groups at a hundred. Want to get them to 1/2" so I guess the next step is to measure the OAL of my rifle.

That's funny, right there!
Brass prep brought my SD down. Trim everything and debur the flash holes. Deburring the flash holes get rid of the burrs on the inside of the hole which will give the primer flame different patterns and ignition inconsistencies.

Weighing the brass into groups of like weights helped a little more, but proved to be more trouble than it was worth (to me) and my use.

[balderclev]

I think I've got the 223 reloading going well. 3/4" groups at a hundred. Want to get them to 1/2" so I guess the next step is to measure the OAL of my rifle.

That's funny, right there!

Don't get the funny part