OAL and crimping and other vexations

[coondogger]

I've been loading some 44 spl. It's a plain Jane recipe; 6.7g Unique and a 200gr jacketed projectile. The OAL for this round is listed as 1.495. But I was getting damaged cases when seating the bullet. So I expanded it a bit more. Which made me think I should crimp it a half turn more. Which seated the bullet deeper. So the OAL is now 1.485. I'm wondering if this will make the pressure too high. I've only loaded five like this so maybe I'll just take them apart and seat the bullets for the rest at 1.505. Hmmm. Any opinions on this?

 

[Atavar]

When turning in the crimp die first grab the seating stem so it doesn’t turn with the die.
You should be able to adjust crimp without affecting OAL.
The threads on the seating stem are the same pitch as the threads on the die.

 

[coondogger]

I used a lighter crimp.

 

[Thomasss]

I've been loading some 44 spl. It's a plain Jane recipe; 6.7g Unique and a 200gr jacketed projectile. The OAL for this round is listed as 1.495. But I was getting damaged cases when seating the bullet.

Your "plain jane recipe is a bit strong at 6.7gUnique. Max is 7.0 for a 200grn. jacketed XTP bullet. Hornady's 10th edition recommends 1.470 COAL. Max. length is 1.50.

 

[coondogger]

Your "plain jane recipe is a bit strong at 6.7gUnique. Max is 7.0 for a 200grn. jacketed XTP bullet. Hornady's 10th edition recommends 1.470 COAL. Max. length is 1.50.

That's out of the Lyman loading manual. They list 6.7grains of Unique as a suggested starting load. Max is 7.5 grains. With an OAL of 1.495. Alliant Unique is a relatively fast burning powder.

 

[mdi]

Normally, and for the last few decades, I seat all bullets to the crimp groove or cannelure disregarding book OAL. All my revolvers are loaded this way (7 different calibers). Most used a plain roll crimp or Profile Crimp. Never any problems. I guess when I started reloading, waaaay pre web, I figgered the bullet designer knew where to locate the groove/cannalure.

 

[GeoDudeFlorida]

That's out of the Lyman loading manual. They list 6.7grains of Unique as a suggested starting load. Max is 7.5 grains. With an OAL of 1.495. Alliant Unique is a relatively fast burning powder.

That doesn’t look like a Lymans bullet. Using the actual bullet maker’s loads is always better.

It’s your gun but to me it looks like you need to seat to the middle of the crimp groove and apply a minimal roll crimp. Unless you’re shooting a tube magazine rifle or a lightweight revolver with a slightly short cylinder, like a Charter Boomer. Then a slightly more aggressive roll crimp might be desirable.

 

[Walkalong]

I used a lighter crimp.

View attachment 1180500

Your OAL needs to be such that the case mouth gets rolled into the center/deepest part of the cannelure.

 

[Walkalong]

Normally, and for the last few decades, I seat all bullets to the crimp groove or cannelure disregarding book OAL. All my revolvers are loaded this way

Yep

 

[coondogger]

I know a lot of people use the cannelure as a bench mark for bullet seating. This ignores Boyle's Law which states that temperature and pressure, in a closed system, are directly proportional. Whereas volume and pressure are share an inverse relationship. So when you ignore the OAL in deference to a specific mark on the bullet, you run the danger of seating the bullet too deeply. This will reduce the volume with a resultant increase in pressure. You might get away with it in say, a 45-70. Not so much with a shorter cartridge like a 44 spl. Put another way, seating to the cannelure is elevating form over function.

 

[lordpaxman]

Looks like you got it sorted out.

So I expanded it a bit more. Which made me think I should crimp it a half turn more. Which seated the bullet deeper.

Expanding, seating and crimping are all set independently according to the die instructions I’ve got. I try to only vary one at a time. For roll crimp, I’ll break out the trimmer since case length matters.
You’re right that reducing COL will lead to a pressure increase but as a reloader you have to adjust for that, usually during load work up. The plunk test, feeding, magazine, cannelure rule, accuracy, perhaps others, may dictate a change to the COL.

 

[JohnMc]

Put another way, seating to the cannelure is elevating form over function.

For cartridges where the crimp is necessary to keep the bullet from moving, such as many revolver cartridges, seating to where the crimp goes into the deepest part of the cannelure is function. The powder charge should be adjusted to match that, as part of load development.

 

[Walkalong]

I know a lot of people use the cannelure as a bench mark for bullet seating. This ignores Boyle's Law which states that temperature and pressure, in a closed system, are directly proportional. Whereas volume and pressure are share an inverse relationship. So when you ignore the OAL in deference to a specific mark on the bullet, you run the danger of seating the bullet too deeply. This will reduce the volume with a resultant increase in pressure. You might get away with it in say, a 45-70. Not so much with a shorter cartridge like a 44 spl. Put another way, seating to the cannelure is elevating form over function.

It won’t make enough difference in pressure to worry with. Matter of fact, it may decrease pressure/prevent good burn with powders like W-296 to the point accuracy etc suffers.

You need a good roll crimp into the middle of the cannelure along with good neck tension in .44 Mag. A few thousandths isn’t going to blow you up.

If you are running the bleeding edge of max, and seating to the center of the cannelure is a bit shorter than the data’s OAL, simply stop a hair short of max.

 

[Walkalong]

For cartridges where the crimp is necessary to keep the bullet from moving, such as many revolver cartridges, seating to where the crimp goes into the deepest part of the cannelure is function. The powder charge should be adjusted to match that, as part of load development.

Beat me to it.

 

[murf]

I know a lot of people use the cannelure as a bench mark for bullet seating. This ignores Boyle's Law which states that temperature and pressure, in a closed system, are directly proportional. Whereas volume and pressure are share an inverse relationship. So when you ignore the OAL in deference to a specific mark on the bullet, you run the danger of seating the bullet too deeply. This will reduce the volume with a resultant increase in pressure. You might get away with it in say, a 45-70. Not so much with a shorter cartridge like a 44 spl. Put another way, seating to the cannelure is elevating form over function.

boyle's law does not apply when you are deflagrating powder. a medium crimp in the middle of the cannelure is recommended here. any problem with that, seat and crimp separately.

luck,

murf

 

[GeoDudeFlorida]

I know a lot of people use the cannelure as a bench mark for bullet seating. This ignores Boyle's Law which states that temperature and pressure, in a closed system, are directly proportional. Whereas volume and pressure are share an inverse relationship. So when you ignore the OAL in deference to a specific mark on the bullet, you run the danger of seating the bullet too deeply. This will reduce the volume with a resultant increase in pressure. You might get away with it in say, a 45-70. Not so much with a shorter cartridge like a 44 spl. Put another way, seating to the cannelure is elevating form over function.

Sounds like you really didn’t need any help after all. Glad you knew what needed to be done. Noted for future reference.

 

[mdi]

Well, I started reloading way pre web so I was not aware of any complex formula, theories or anybody's "law". I felt the bullet designer knew more than I did so I used the designer's crimping location. This has worked for me (poor simple ole me), quite well, for thousands of rounds and 40+ years later. Never any unintentional max loads and all very safe.

 

[coondogger]

Well, I started reloading way pre web so I was not aware of any complex formula, theories or anybody's "law". I felt the bullet designer knew more than I did so I used the designer's crimping location. This has worked for me (poor simple ole me), quite well, for thousands of rounds and 40+ years later. Never any unintentional max loads and all very safe.

The 'law' has to do with pressures in a closed system, and what affects those pressures. Pressures are increased by an increase in temperature or a decrease in volume of the closed system. I have a degree in chemistry and it has come in handy with re-loading. All I'm saying here is the cannelure provides a good estimate of the right position for bullet seating but OAL minimum is more scientifically sound.

 

[Charlie98]

All I'm saying here is the cannelure provides a good estimate of the right position for bullet seating but OAL minimum is more scientifically sound.

Actually... it might be, or it might not be. I think you are overthinking it.

FWIW, given your powder... Unique... the minute differences in both charge weight and bullet seating depth have very little effect on the load, and how the powder burns. At that charge weight, with that weight of bullet, Unique is going to burn relatively well no matter the COL. In your 'form over function' comment, you missed one... safety. While the .44SPC isn't necessarily a heavy recoiling round, I would be roll crimping into that cannelure to remove any chance of bullet offset from recoil or other forces.

 

[Walkalong]

Actually... it might be, or it might not be. I think you are overthinking it.

Agreed, and I’m certainly guilty of it at times

 

[Walkalong]

The 'law' has to do with pressures in a closed system, and what affects those pressures. Pressures are increased by an increase in temperature or a decrease in volume of the closed system. I

No one is disagreeing with that

 

[JohnMc]

The 'law' has to do with pressures in a closed system, and what affects those pressures. Pressures are increased by an increase in temperature or a decrease in volume of the closed system. I have a degree in chemistry and it has come in handy with re-loading. All I'm saying here is the cannelure provides a good estimate of the right position for bullet seating but OAL minimum is more scientifically sound.

Reducing the number of gas molecules (moles) also reduces the pressure, per the ideal gas law, so adjust the powder charge accordingly.
Don't neglect the mechanical part of the load, in this case best utilization of the cannelure, in favor of the chemistry part, the powder (and primer).

 

[9mmepiphany]

All I'm saying here is the cannelure provides a good estimate of the right position for bullet seating but OAL minimum is more scientifically sound.

I'm not disagreeing with you. I don't have a degree in chemistry, but i did take some classes, and based on that, and other classes in reasoning and human behavior, I'm pretty confident in saying that you're over thinking this...or at least over emphasizing a different priority than others.

I should preface this by saying that I don't reload .44Spl and don't use Unique at all... if you think this negates my experience, so be it.
I load .38Spl using Clays. I'm loading either a 160gr RN polymer coated or a 158gr FN plated bullet. My goal is to reach a Power Factor for competition which works out to about 825fps...so a little hotter than factory .38Spl (755fps) but not as hot as +P (975fps)

The plated bullet has a cannelure and I seat the bullet deep enough to be able to roll crimp into the middle of it (I trim my cases). I think I might have measured my OAL a while back and it fell within a reasonable range checking the Lyman manual for 158gr case bullets. I use that same OAL for the bullets without a cannelure, by eye balling it. My thought process is that I don't mind a little extra pressure, if seating a bit deeper, if it keeps the bullet from pulling forward during strings of rapid fire. This process seems to have worked for several ten of thousands of rounds without ill effects

 

[mdi]

My only reply is I am very grateful I started reloading with a Lee Loader and the included instruction/data sheet. If given a chance I will overthink most issues I come across, but many times it's just a fool's errand...

 

[Walkalong]

If given a chance I will overthink most issues

Isn't that most of us........especially when we're young.