Felt Snappiness: 357 Mag v. 38 Short Colt

[jski]

Your theory does not hold up. Berry's 38/357 bullet is longer than the 9mm bullet. From Berry's website:

9mm 124 gr. FP, length = .512

38/357 125 gr. FP length = .518

124 Grain 9mm Bullets | Flat Nose Bullet | Reloading Bullets

Berry's 124 Grain 9mm bullets for reloading are flat nose bullets & can be bought in bulk. Shop our 9mm plated bullets for unbelievable accuracy!

www.berrysmfg.com

125 Grain 357 Bullets | 38 Special Bullets for Reloading

The 38 Special 125 Grain bullets sold and manufactured by Berry's Bullets are some of the best 38 special bullets you can buy for consistency and precision.

www.berrysmfg.com

Then the bullet geometry has to be different … a longer cone and a shorter base on the 357 ? Something.

Also the 38 SC case capacity is greater than the 9mm’s.

 

[Walkalong]

They’re not? Then what are they?

Because primers lie. They’re subjective.

But I know better than to respond in one of your threads. IMHO, you’re not looking for help, just affirmation.

 

[jski]

Because primers lie. They’re subjective.

But I know better than to respond in one of your threads. IMHO, you’re not looking for help, just affirmation.

This thread has been VERY, VERY helpful for me with this project! Undoubtedly, it has also made many more people aware of the 38 SC and its modern uses.

 

[Mr_Flintstone]

Just for my own peace of mind, I decided to measure some Starline 38 SC brass and do a detailed run through Gordon's Reloading Tool. I took some factory Starline 38 SC brass and measured its internal capacity at 13.9 gr H2O and the case length at 0.756". I then input those parameters into GRT with a Hornady 125 gr XTP-FP (which has the same dimensions as the Berry's 125 gr FP) bullet seated to an overall length of 1.025" and 6 grains of True Blue powder. I was actually shocked at the results of the simulation. Gordons shows this load to produce a peak pressure of 49,600 PSI. No wonder it felt snappy.

I ran the simulation again with the overall length changed to that of Hodgdon's 9mm recommendation of 1.035 plus the .004" difference between 9mm and .38 SC brass to get 1.039". This resulted in a pressure of just over 44,000 PSI. Not satisfied yet, I kept incrementally moving the bullet outward until I achieved a .357 Magnum compliant pressure. This resulted in an OAL of 1.08" and a pressure of 34,000 PSI. It's amazing the difference in pressure with this .055" difference in seating depth.

Granted this is only a simulation, and may vary from actual pressure, but it indicates to me that this may not be a safe load for .38 SC brass in a .357 revolver. Maybe someone with Quickload will come along and double check my calculations.

 

[reddog81]

Just for my own peace of mind, I decided to measure some Starline 38 SC brass and do a detailed run through Gordon's Reloading Tool. I took some factory Starline 38 SC brass and measured its internal capacity at 13.9 gr H2O and the case length at 0.756". I then input those parameters into GRT with a Hornady 125 gr XTP-FP (which has the same dimensions as the Berry's 125 gr FP) bullet seated to an overall length of 1.025" and 6 grains of True Blue powder. I was actually shocked at the results of the simulation. Gordons shows this load to produce a peak pressure of 49,600 PSI. No wonder it felt snappy.

I ran the simulation again with the overall length changed to that of Hodgdon's 9mm recommendation of 1.035 plus the .004" difference between 9mm and .38 SC brass to get 1.039". This resulted in a pressure of just over 44,000 PSI. Not satisfied yet, I kept incrementally moving the bullet outward until I achieved a .357 Magnum compliant pressure. This resulted in an OAL of 1.08" and a pressure of 34,000 PSI. It's amazing the difference in pressure with this .055" difference in seating depth.

Granted this is only a simulation, and may vary from actual pressure, but it indicates to me that this may not be a safe load for .38 SC brass in a .357 revolver. Maybe someone with Quickload will come along and double check my calculations.

When looking at the Hodgdon 9mm data I was surprised to see quite a variation in load data depending on the bullet used and OAL. Those calculations seem to confirm small changes can make a big difference. The SC case might have a tiny bit more volume but seating a bullet so short negates the 2% extra case capacity.

 

[AJC1]

Just for my own peace of mind, I decided to measure some Starline 38 SC brass and do a detailed run through Gordon's Reloading Tool. I took some factory Starline 38 SC brass and measured its internal capacity at 13.9 gr H2O and the case length at 0.756". I then input those parameters into GRT with a Hornady 125 gr XTP-FP (which has the same dimensions as the Berry's 125 gr FP) bullet seated to an overall length of 1.025" and 6 grains of True Blue powder. I was actually shocked at the results of the simulation. Gordons shows this load to produce a peak pressure of 49,600 PSI. No wonder it felt snappy.

I ran the simulation again with the overall length changed to that of Hodgdon's 9mm recommendation of 1.035 plus the .004" difference between 9mm and .38 SC brass to get 1.039". This resulted in a pressure of just over 44,000 PSI. Not satisfied yet, I kept incrementally moving the bullet outward until I achieved a .357 Magnum compliant pressure. This resulted in an OAL of 1.08" and a pressure of 34,000 PSI. It's amazing the difference in pressure with this .055" difference in seating depth.

Granted this is only a simulation, and may vary from actual pressure, but it indicates to me that this may not be a safe load for .38 SC brass in a .357 revolver. Maybe someone with Quickload will come along and double check my calculations.

CIP runs 357 a little hotter than Sammi like 40k but 49k is to far out of the box. These are the exact senerios that compell me to push grt on as many as possible. I hope they do the runs before loading and pulling the trigger.... some information is more important before the results

 

[Mr_Flintstone]

When looking at the Hodgdon 9mm data I was surprised to see quite a variation in load data depending on the bullet used and OAL. Those calculations seem to confirm small changes can make a big difference. The SC case might have a tiny bit more volume but seating a bullet so short negates the 2% extra case capacity.

They do make a huge difference sometimes. I remember somewhere seeing a load for some powder where there was only .1 gr difference between minimum and maximum loads for 9mm.

What I found when I looked up the case volume for 9mm was that it averaged about 12.5 gr H2O but the range of volumes went from 12.3 to 13 gr, which overlaps with what I found for .38 SC. I'm sure that the average 38 SC case is a smidge bigger than the average 9mm, but there may be times when a 9mm case may actually be larger than a given 38 SC case.

 

[jski]

Just for my own peace of mind, I decided to measure some Starline 38 SC brass and do a detailed run through Gordon's Reloading Tool. I took some factory Starline 38 SC brass and measured its internal capacity at 13.9 gr H2O and the case length at 0.756". I then input those parameters into GRT with a Hornady 125 gr XTP-FP (which has the same dimensions as the Berry's 125 gr FP) bullet seated to an overall length of 1.025" and 6 grains of True Blue powder. I was actually shocked at the results of the simulation. Gordons shows this load to produce a peak pressure of 49,600 PSI. No wonder it felt snappy.

I ran the simulation again with the overall length changed to that of Hodgdon's 9mm recommendation of 1.035 plus the .004" difference between 9mm and .38 SC brass to get 1.039". This resulted in a pressure of just over 44,000 PSI. Not satisfied yet, I kept incrementally moving the bullet outward until I achieved a .357 Magnum compliant pressure. This resulted in an OAL of 1.08" and a pressure of 34,000 PSI. It's amazing the difference in pressure with this .055" difference in seating depth.

Granted this is only a simulation, and may vary from actual pressure, but it indicates to me that this may not be a safe load for .38 SC brass in a .357 revolver. Maybe someone with Quickload will come along and double check my calculations.

Try running it using Western Powders’ empirical data:

BERRY RN 124 gr
max: 5.9 & 1,115 FPS
PSI 34,012

See if you get 34,012 PSI ? For a 9mm. Those numbers seem way off … well actually ridiculous.

I’ve shot full house Remington 158 gr 357s out of this gun and those 38 SC loads are creampuffs in comparison.

 

[jski]

I can always back them out a bit and re-seat them but those values seem so extreme …

 

[Mr_Flintstone]

Try running it using Western Powders’ empirical data:

BERRY RN 124 gr
max: 5.9 & 1,115 FPS
PSI 34,012

See if you get 34,012 PSI ? For a 9mm. Those numbers seem way off … well actually ridiculous.

I’ve shot full house Remington 158 gr 357s out of this gun and those 38 SC loads are creampuffs in comparison.

I ran those numbers and I got 34,420 PSI. Not dead on, but close enough for Government work. The big difference there is that the charge is lighter, the bullet is a little lighter, it is set much farther out (1.160") and is of a different profile than the 125 grain bullet at 1.025" with 6.0 gr.

 

[jski]

I ran those numbers and I got 34,420 PSI. Not dead on, but close enough for Government work. The big difference there is that the charge is lighter, the bullet is a little lighter, it is set much farther out (1.160") and is of a different profile than the 125 grain bullet at 1.025" with 6.0 gr.

I guess I’ll back them out to 1.06” 1.09” and see what I see.

 

[jski]

I have to wonder if these sim apps are simply interpolating between empirical values. Without a means to check their calculated values … ?

BUT that’s for another thread

 

[Mr_Flintstone]

I have to wonder if these sim apps are simply interpolating between empirical values. Without a means to check their calculated values … ?

BUT that’s for another thread

They use some algorithms that aren’t available to us mere mortals. They use burn rates, two or three kinds of densities, and some other things, and then wave a magic wand to give us pressure and velocity values. They aren’t always on the dot, but with correct measurements of case length, bullet weight, powder weight, and seating depth you get a pretty close estimate. I’d go out on a limb and say that Quickload is a little more useful because it has more powders and bullets available, but GRT does pretty good for the price… Free.

I use it a lot for loads that don’t seem to appear in many, if any load manuals; i.e. obsolete and semi-obsolete Last thing I used it to create data for was 6.5 Carcano with IMR 4227. You got to be careful though and use a little experience and intuition to build from cartridges close to what you are looking for.

 

[jski]

They use some algorithms that aren’t available to us mere mortals. They use burn rates, two or three kinds of densities, and some other things, and then wave a magic wand to give us pressure and velocity values. They aren’t always on the dot, but with correct measurements of case length, bullet weight, powder weight, and seating depth you get a pretty close estimate. I’d go out on a limb and say that Quickload is a little more useful because it has more powders and bullets available, but GRT does pretty good for the price… Free.

I use it a lot for loads that don’t seem to appear in many, if any load manuals; i.e. obsolete and semi-obsolete Last thing I used it to create data for was 6.5 Carcano with IMR 4227. You got to be careful though and use a little experience and intuition to build from cartridges close to what you are looking for.

I going to back them out to 1.09” and see. Well, some of them.

 

[mcb]

They use some algorithms that aren’t available to us mere mortals. They use burn rates, two or three kinds of densities, and some other things, and then wave a magic wand to give us pressure and velocity values. They aren’t always on the dot, but with correct measurements of case length, bullet weight, powder weight, and seating depth you get a pretty close estimate. I’d go out on a limb and say that Quickload is a little more useful because it has more powders and bullets available, but GRT does pretty good for the price… Free.

I use it a lot for loads that don’t seem to appear in many, if any load manuals; i.e. obsolete and semi-obsolete Last thing I used it to create data for was 6.5 Carcano with IMR 4227. You got to be careful though and use a little experience and intuition to build from cartridges close to what you are looking for.

If you look at the documentation that comes with Quickloads it gives a pretty detailed explanation of the physics its based on how the simulation is constructed, going from the shape of the powder grains on up. It's pretty hefty on the thermodynamics and heat transfer and a modest amount of fluid dynamics and good old dynamics but at least with Quickloads the documentation does a pretty good job of explaining what it is and is not doing. That said I would not have wanted to tackle that document without a good BS in Mechanical, Chemical or similar engineer discipline. It's a good background to the program so you know what it can and can't model.

 

[jski]

Sounds impressive

 

[jski]

It's been an education.

 

[Bill M.]

Are we agreed then that the recoil effect is probably a result of the porting and a difference in the amount of powder in the .357 case?

 

[jski]

Are we agreed then that the recoil effect is probably a result of the porting and a difference in the amount of powder in the .357 case?

The biggest takeaway is that seating depth, measured in hundredths and thousandths of an inch, can have major effects on the max pressure for that cartridge.

Small differences in seating depth can produce large differences in pressure.

 

[AJC1]

The biggest takeaway is that seating depth, measured in hundredths and thousandths of an inch, can have major effects on the max pressure for that cartridge.

Small differences in seating depth can produce large differences in pressure.

So we have taken the ease and forgiving nature of the 38 as a learners cartridge, and made it an advanced loading.... it's not like the guys doing this are new, but it might be beneficial for the guys wanting to copy you at the range to be aware....

 

[Mr_Flintstone]

Speer #11 states this on the 9mm description page

“If the bullet is easily moved deeper into the case, malfunctions may occur. But more important, loads that produced 28,000 cup went to 62,000 cup when bullets were purposely seated .030” deeper! Thus, it is of the utmost importance that bullets do not become deeper seated in the feeding cycle.”

I think the warning remains in later printings, but without the specific pressures. Since 38 Short Colt in this case is essentially a rimmed 9mm, the same should apply to the 38 Short Colt loadings at this pressure.

 

[mcb]

Speer #11 states this on the 9mm description page

“If the bullet is easily moved deeper into the case, malfunctions may occur. But more important, loads that produced 28,000 cup went to 62,000 cup when bullets were purposely seated .030” deeper! Thus, it is of the utmost importance that bullets do not become deeper seated in the feeding cycle.”

I think the warning remains in later printings, but without the specific pressures. Since 38 Short Colt in this case is essentially a rimmed 9mm, the same should apply to the 38 Short Colt loadings at this pressure.

But this increase in pressure is also very dependent on the particular powder. For a given amount of bullet set back the pressure increase will be greater if your using a fast powder vs a slower powder assuming your slow powder does not become a compressed load. Also with a revolver since the bullet is going into the throat of the cylinder and not directly into the riflings we would expect the pressure spike of a setback bullet to be slightly less and with 38 Short Colt in the long 357 Magnum chamber this potentially mitigates the pressure spike a bit more. There are lots of variable the effect that pressure spike on bullet set back. Sometimes it's dangerous, sometimes its not, something to be aware of but its not always a grenade.

We are also reloading 38 Short Colt for a revolver so OAL is not nearly as critical since we don't have to fit in a magazine or feed from that magazine. So load them long and adjust the powder charge to get the velocity you want. My own 38 Short Colt is loaded at 1.19 inches long but I am using a 160 gr bullet.

Also bullet setback is rarely a problem for a revolver since we are not feeding from a magazine. You far more likely to have bullets creep out of the cases due to recoil and the only danger there is locking up the revolver but that is very unlikely with 38 Short Colt in a long 357 Magnum chamber/cylinder, The bullet could come completely out of the case and not get past the end of the cylinder.

 

[AJC1]

But this increase in pressure is also very dependent on the particular powder. For a given amount of bullet set back the pressure increase will be greater if your using a fast powder vs a slower powder assuming your slow powder does not become a compressed load. Also with a revolver since the bullet is going into the throat of the cylinder and not directly into the riflings we would expect the pressure spike of a setback bullet to be slightly less and with 38 Short Colt in the long 357 Magnum chamber this potentially mitigates the pressure spike a bit more. There are lots of variable the effect that pressure spike on bullet set back. Sometimes it's dangerous, sometimes its not, something to be aware of but its not always a grenade.

We are also reloading 38 Short Colt for a revolver so OAL is not nearly as critical since we don't have to fit in a magazine or feed from that magazine. So load them long and adjust the powder charge to get the velocity you want. My own 38 Short Colt is loaded at 1.19 inches long but I am using a 160 gr bullet.

Also bullet setback is rarely a problem for a revolver since we are not feeding from a magazine. You far more likely to have bullets creep out of the cases due to recoil and the only danger there is locking up the revolver but that is very unlikely with 38 Short Colt in a long 357 Magnum chamber/cylinder, The bullet could come completely out of the case and not get past the end of the cylinder.

Would it not be ideal to treat this more like 357 sig where a powder is selected to fill the case and not allow setback.

 

[mcb]

Would it not be ideal to treat this more like 357 sig where a powder is selected to fill the case and not allow setback.

That would not be a bad plan but if you are looking to mitigate recoil you will probably want to use smaller quantities of faster powder. My own load it not about maximum kinetic energy going down range but to meet the Minor PF requirement of USPSA, hence the heavy bullet. A small quantity of Titegroup gets me there and adds minimal to the recoil since its such a light charge.

 

[Mr_Flintstone]

But this increase in pressure is also very dependent on the particular powder. For a given amount of bullet set back the pressure increase will be greater if your using a fast powder vs a slower powder assuming your slow powder does not become a compressed load. Also with a revolver since the bullet is going into the throat of the cylinder and not directly into the riflings we would expect the pressure spike of a setback bullet to be slightly less and with 38 Short Colt in the long 357 Magnum chamber this potentially mitigates the pressure spike a bit more. There are lots of variable the effect that pressure spike on bullet set back. Sometimes it's dangerous, sometimes its not, something to be aware of but its not always a grenade.

We are also reloading 38 Short Colt for a revolver so OAL is not nearly as critical since we don't have to fit in a magazine or feed from that magazine. So load them long and adjust the powder charge to get the velocity you want. My own 38 Short Colt is loaded at 1.19 inches long but I am using a 160 gr bullet.

Also bullet setback is rarely a problem for a revolver since we are not feeding from a magazine. You far more likely to have bullets creep out of the cases due to recoil and the only danger there is locking up the revolver but that is very unlikely with 38 Short Colt in a long 357 Magnum chamber/cylinder, The bullet could come completely out of the case and not get past the end of the cylinder.

I’m not disagreeing. All of this is true, but the basic premise is still sound. You will still get the same pressure whether you have bullet setback from a 9mm or intentional short seating in 38 SC. And while it’s true that most of the 38 SC loads will reach max pressure in the cylinder, unless you have some special pressure testing apparatus, you have no idea of knowing how much pressure is bled from the system. Some, yes; but how much? 1,000 psi, 5,000 psi, who knows? Personally I find it prudent to err on the side of caution. That’s why computer modeling is helpful. Although it isn’t 100% accurate, it does give you some idea of the pressures you’re looking at with a particular load.

That said, a pressure of 40,000 psi or so is not likely to blow up a .357 Magnum revolver, but it will cause more wear on the gun and introduce more metal fatigue in the cylinder than rounds fired at 35,000 psi. It may even be that pressures of 50,000 psi can be tolerated for a while, but eventually something catastrophic is likely to happen. I just think that it is important for people to know how small capacity rounds can spike in pressure rather quickly. Yes, it can and has been done for years, but you just don’t have the forgiving nature of a .357 magnum case when using something like a 38 SC case.