Maximum length of cartridge???

[Delco]

Hello,
I am new to this forum, and I'm glad to find folks that are so interested in reloading and firearms.
I have been reloading for a short time, about 6 months. I started reloading for my 38/357 and for my great old Colt New Servive in 38-40.
I have a Lee turret press, and reloading several loads for the revolvers is very straight forward.
I have my CCW and deceided to reload 380 and 9mm.
I have the new Lyman and the new Lee reloading manuals. They both refer to the maximum length of the finished cartridge. What is this? Saying it's a maximum length infers that cartridges can be shorter, but how much shorter?
Just for a check, I measured several factory new and reloaded cartridges.
Lets take 9mm. The "maximum overall length" in the reloading manual is 1.169". The shortest factory cartridges are from Blue Star at 1.080" The American Eagle are 1.152", even the expensive Federal Hydra Shock are 1.121".
The factory 380 ammo is also shorter that the max overall length in the manuals.
Apparently the factories don't care about the length or it's not that important.
But wait, in both manuals they state that seating bullets in too far causes very high pressures. I can understand this.
So, what's the answer?
Thank,
Del

[wncchester]

"...the factories don't care about the lenghth or it's not that important."

They really don't care what any reloading manual says, it's not that important. Certainly not as critical as some seem to believe.

Proof: If it was all that critical the various OAL figures would more closely match.

The book's OAL is no more than the length they used to develop the data they publish. Neither their suggested powder charges or OAL is anything more than a rough guide WE have to carefully impliment and observe for potential problems.


"But wait, in both manuals they state that seating bullets in too far causes very high pressures. I can understand this. So, what's the answer?"

When they say seating "in too far" raises pressures they mean in too far, not "any at all."

Answer is, do your homework; Load as needed to function in your firearm then "Start low, work up only..." etc. Following that rule will make any rational changes in components or loading method safe, ignore it and no book info is automatically safe.

[zippy13]

Greetings Delco, and welcome aboard…

As far as ammo for your CCW, may I caution you against using reloads. Not for anything to due with performance, but for political reasons. Should you have to defend yourself, you don't want some bleeding-heart attorney labeling you as the gun nut who used special home-made ammunition against some poor, misunderstood, homeless person who's only problem was asking for a handout a little too aggressively.

[Delco]

I didn't expect to get replies this quickly.
I hear you on reloads for self defense. I think I will stick to the factory high performance loads. It's impossible to get the bullets that they use in some of the great defense loads. I reload to target shoot cheaply and a lot.
The availability of ammo and ammo components is a huge problem unless you have the cash to buy overpriced loaded ammo.

Winchester, you have a great style in answering. I like the copy paste style.
You obviously have a lot of experience looking at your info.
What you say about OAL is what I thought too. I just needed someone with experience to confirm it.

[Delco]

Sorry Wncchester, I just looked at your name again. I thought it was Winchester.
How do you do the copy and past in a reply? Do you open up 2 windows so you can copy one section in one window and then paste it in another window?

[Xfire68]

Well if your looking at factory ammo of the same bullet weight, type, length and shape then I could see why you would compare the OAL of these rounds but, most are not the same and would as they do in the reloading books require different OAL's. Different powders and amounts require different OAL's as well.

[Delco]

If that was true, then the manuals would list a different OAL for different bullet weights. Actually that makes more sense to me.
They list one length for all bullet weights in a particular caliber.
So, what is the correct length for a 90 grain fmj or a 147 gr hollow point or fmj in 9mm? While these are extremes, they are valid loads.
If you seat the 90gr and the 147gr to get the same OAL, the 90 grain is not seated very deep, in fact it looks like I could force it out.
I emailed Lee and they finally responded after days with their legal responsibility. They said to use all the data in their manual.

[Scorch]

Maximum cartridge overall length (COAL or OAL) is established by SAAMI to ensure manufacturers produce ammunition that will function through the wide variety of firearms produced and chambered for a given cartridge. This does not mean you cannot load the cartridges to different lengths, just that they may not work through all firearms made for that cartridge. You can make them shorter and they will still work, but if you make them longer you run the risk of the round not feeding through somebody's firearm. You rindividual firearm may accept cartridges that are longer than SAAMI maximum overall length, but your neighbor's rifle may not. Does that make sense?

[Delco]

That makes perfect sense.
I did consider the operation in the action of a handgun or rifle. A too long cartdridge certainly would affect it's movement in the action.
I guess a too short one would affect it also.
I always start loads with the low power ones. I do try several different powders and different bullet weights.
I write everything down and mark the ammo so I know which is which.
Thanks, Scorch, Wncchester, Zippy13, and Xfire68.
I now know where to get my reloading questions answered.
Much better than waiting for Lee or Lyman to answer an email.

[wncchester]

"Winchester, you have a great style in answering. I like the copy paste style. "

First, no offense taken, I get Winchester (and much worse!) often. It's not my handle but it's NOT a bad thing!

My cut and paste is straight "copy" and "paste", copied from the question with the "EDIT" function and pasted straight into my open "Reply" window. Purpose is to keep what I'm saying properly focused, sometimes that seems to get lost! (And frequently someone twists my words and then gets upset about what I didn't even say! Ah well, no matter.)


SAAMI doesn't establish max OAL, per se. They do establish rational throat/leade minimums, same as other chamber dimensions. The extra throat any manufactor chooses to cut for extra freebore is up to them. Obviously the throat has to accept the worst/longest bullet. Usually that will be enough for the heaviest available round nose bullet seated to the base of the neck. A second practical factor for length is the action (or revolver cylinder) length, which then limits the max length of the magazine, which limits the length of the cartridge. Single shots can be seated hard into the lands OR so long the bullets may fall out.

All meaning OAL is NOT a specific point, no specfic point is SAAMI recommended for it. In all my decades of reloading tens of thousands of rounds for dozens of different rifles and handguns I have never considered or even looked at a book OAL for anything. They don't know my guns, I do. Meaning, I find what works in my rig and use it, that's what the book makers do.

Nor do I agonize over my books not listing exactly the case, primer, bullet brand/style (or even precisely the same bullet weight) I will be using. The simple adage to "start low..." etc., takes care of it all.

[SL1]

Delco,

I think you are getting some confusing answers and a little mis-information in the previous responses.

First, SAAMI DOES specify a minimum and a maximum cartridge overall length (COL) in its standards. For 9mm, the drawings that I have show max = 1.169" and min = 1.095".

Many reloading manuals will show the SAAMI maximum in the front of a section for the data on a particular cartridge, just as information.

BUT, most manuals will NOW show the COL that they used when they developed the data for each bullet in their data, and that may NOT be the SAAMI max. It is ususally what worked best for them with the particular nose shape of the bullet in THEIR test rifle. (NOT the test barrel where they took the pressure readings, but the sample commercial gun where they shot the cartridges to get the velocity figures that they publish with the charge weigths.)

For short, fairly high pressure cartridges like the 9mm, pay close attention to the COL listed FOR THE ACTUAL DATA developed with a particular bullet. Changing the COL from the maximum to the minimum can definitely blow up your gun if the data for the max charge weight was developed with the SAAMI max COL. For example, the QuickLOAD program showes a charge weight of Bullseye powder that produces the SAAMI max pressure of 35,000 psi with a particular bullet at the SAAMI max COL would produce 56,000 psi if the COL was reduced to SAAMI minimum. Some other examples are not so bad, and some are worse. So, changing COL from WHAT WAS USED TO PRODUCE THE DATA needs to be considered carefully.

In revolvers and most rifles, that isn't really a problem, because you can just use the same COL as the data if you can't figure-out the results of changing the COL so that you can do it safely. But, for autoloaders, the feed cycle can be very finicky, and you may NEED to change COL to get your gun to function reliably.

You will see a lot of advice to "start low and work-up looking for pressure signs." But, it is misleading to apply that advice to auto-loading pistols like the 9mm because, at the SAAMI max pressure for THAT cartridge, pressure signs are not obvious. In particular, looking at primers can be misleading to a dangerous degree.

Making a COL shorter should be done with a corresponding reduction in powder charge weight that needs to be computed BASED ON THE CHANGE IN POWDER SPACE LEFT UNDER THE BULLET WHEN IT IS SEATED IN THE CASE. To do that, you need to know the space inside your case, and compute how much is left with the bullet seated to various depths. Typically, the space in an empty case is measured by the weight of water that it holds. Then, the space occupied by the bullet is computed by squaring the bullet diameter (in inches), multiplying by Pi, and dividing by 4, then multiplying by the length of the bullet that is below the case mouth (in inches). Then, you can multiply by 252.8 grains of water per cubic inch to get the space the bullet occupies in the same units of measure as you have for case capacity. Subtracting the case space occupied by the bullet (in grains of water) from the case capacity (in grains of water) leaves the powder space (in grains of water).

To get YOUR case capacity, weigh an empty case from a round fired in YOUR gun, then weigh it again when filled LEVEL across the mouth with water. (Leave the spent primer in the case when you do that.) Also measure the length of the SAME case and the length of your bullet. The amount of bullet length inside the case is then the the sum of the bullet and case length minus the COL to which that bullet is loaded.

Once you have computed the powder space left inside the case for YOUR COL and for the COL used in your pressure-tested load manual data, you can adjust the powder charge weights in the data for YOUR COL by the ratio of the powders spaces. For example, if the pressure-tested data was taken with a COL that left 10.0 grains of water capacity for its powder space, but you wanted to use a COL that allowed only 8.2 grains, then you would need to reduce the powder weights in your data by a factor of (8.2 ÷ 10.0 =) 0.82 to maintain approximately the same pressures as the loads in the data. This is known is keeping the same "load density", and it works fairly well for relatively small changes in load density, and is usually slightly conservative for powder space REDUCTIONS. But, it is also somewhat non-consservative for powder space increases, so don't get carried away. (And, if you change load density, note that the PRESSURE goes up faster than the "load density", actually by something more than the square of load density, so don't use this "little bit of knowledge" to try to compute a charge weight to get the last few thousand psi into a load where the manual stopped at a charge weight somewhat below the SAMMI max pressure for your cartridge. There are a lot of GOOD SAFETY reasons that some powders are not taken to the SAAMI maximum pressures.)

I hope this helps. Ask for more details if you need clarification.

SL1

[Delco]

I Just took a closer look at the load data in the LEE manual and the Lyman manual, You are absolutely correct SL1, they DO show the OAL for the loads listed.
If I had just looked closer and read the data, I would have seen that.
Oh well, I got some interesting answers.
I don't have to worry that I am loading something with excessive pressure.
Work up slowly and document everything.
Thanks,