Chamber pressures. 38 low recoil factory ammo?

ZVP · July 2, 2016, 03:30 PM

I' d like to fire Horniday 125 gr low recoil H/P SELF DEFENSE AMMO THROUGH MY Cobra .38 Derringer.
My question is does this light bullet loads develop more pressure than Factory loaded 158 grain bullets? It dosen't say anything on the Horniday box about thesending being a high pressure load as the +P ammo does.
Thanks again
Dave

briandg · July 3, 2016, 06:41 AM

standard pressure rounds are supposed to be that, they are not to exceed standard pressures as provided by SAAMI. Any pistol designed for standard rounds can fire a standard round.

Now a +P round is a different thing. The plus is loaded to reach a significantly higher velocity and generates a significantly higher pressure, and this can only be fired in guns specifically suited for plus rounds.

If your cartridges are not specifically listed as plus, they will be standard rounds. your handgun, sold as a .38 special is is supposed to be safe to fire with any standard .38 ammo.

Nick_C_S · July 3, 2016, 11:42 AM

Briandg has it right. Although I would have reworded this sentence . . .

Quote:

The plus is loaded to reach a significantly higher velocity and generates a significantly higher pressure . . .

To this . . .

The "+P" is loaded to reach a significantly higher pressure, and thus, generate a significantly higher velocity.

Just makes it more clear in my head. Pardon my hair splitting

.

reddog81 · July 4, 2016, 09:13 AM

I would imagine any low recoil load is going to have less pressure than an average 38 special load. Additionally +P loads don't develop what I would consider significant higher pressures and velocities. +P is only about 15% higher pressure and velocities. .357 Magnum develops significantly higher pressures and velocities.

38 special SAAMI pressure is 17,000 PSI
+P is 20,000
.357 is 35,000

This holds true for 9mm and .45 ACP. However, 45 Colt is the exception to this rule and its +P pressure is almost double.

**Aguila Blanca** · July 4, 2016, 10:02 AM

The new "short barrel" rounds that have reached the marketplace recently are different from "standard" ammo in two respects. First, to counteract the loss of velocity due to powder burning in the barrel after the bullet has left, the "short barrel" ammo is loaded with faster-burning powder than standard self-defense ammo. Second, the bullets are designed to expand reliably at lower velocities than standard ammo.

The faster powder very likely does result in slightly higher pressures than "standard" ammo of the same bullet weight, but probably not into the +P range. It may not be an increase in maximum pressure so much as a difference in the pressure rise curve.

It's not marked +P so it isn't +P, and that should tell us that it's safe in any firearm that's designed to handle standard ammunition.

briandg · July 4, 2016, 11:51 AM

Red dog, even 15% is significant when you are talking about the differences in pistol s. Don't compare it to a .357, they aren't the same.

You can warp aluminum frame revolvers. A friend inherited a pistol from his grandfather, with a few boxes of plus ammo. It had splits at the back of the barrel. That increase in pressure is significant, and that's why it's labeled as as high pressure, and they are labeled with warnings to use only in plus labeled guns..

reddog81 · July 4, 2016, 12:41 PM

If I owned a gun that was going to fall apart after shooting a couple hundred rounds of +P ammo I'd be afraid to shoot any ammo in it.

Any gun should be able to handle a proof load and not self destruct. If your gun is past that point I'd consider it a wall hanger.

briandg · July 4, 2016, 07:35 PM

Proof loads are fired a few times. Enough to be sure that there are no serious flaws in metal or materials, not to test the limitations of the design.

There are handguns that are not supposed to be used with plus rounds. There are pistols that can't be used with heavy .45 using heavy rounds in weaker guns will eventually cause damage and using standard rounds in those same pistols is safe. You know, those are the rules, the people who make the things and set the standard. Failure to follow standards is dangerous.

I'm not sure what your posts actually mean, but it kind of sounds like you were suggesting that it doesn't matter, and that people can use either one. That's not true. If you are telling the poster that he can use plus pressure rounds in any handgun made you are being very irresponsible and may lead to him either damaging his pistol or even getting hurt.

reddog81 · July 4, 2016, 11:21 PM

I'm not suggesting to use + P rounds in guns not rated for +P loads but realistically the 15% pressure difference isn't that much. If the gun doesnt have a 15% safety margin built into the design i'd be hesitant to shoot the gun much with any ammo. If a couple hundred rounds of +P is going to hurt a gun then realistically it's not that high quality of a gun to begin with

Like I said previously 45 Colt +p is an entirely different animal

**Aguila Blanca** · July 5, 2016, 07:05 AM

Okay, let's say +P represents a 15% increase over standard ammo of the same caliber. Let's also assume that you have a pistol with a 15% safety factor built in. As long as you always shoot standard ammo, you always have a 15% safety factor -- with every shot.

Start shooting +P and now you have zero safety factor -- with every shot. But, hey ... it's only 15%, so it's no big deal.

I own a couple of .38 Special revolvers of recent manufacture that are rated for standard ammo but not for +P. The manufacturer says they are safe for "occasional" use with +P, but a steady diet of +P will damage the guns. So I don't shoot +P through them, and I don't regard that as in any way reflecting on the quality of the firearm. If I buy a compact pickup that's rated to tow 5,000 pounds, is it a defect that it won't safely tow 6,000 pounds? No -- it wasn't designed to tow 6,000 pounds. Simple.

reddog81 · July 5, 2016, 08:17 AM

What does occasional use of +p mean? Either it can handle +P or it can't.

**Aguila Blanca** · July 5, 2016, 09:01 AM

Quote:

Originally Posted by redog81

What does occasional use of +p mean? Either it can handle +P or it can't.

Not at all.

You seem to think that a catastrophic kaboom is the only mode of failure for a handgun. Prolonged, frequent use of +P loads in handguns not designed for such pressures can result in other issues, such as frame stretching, forcing cone erosion, cylinder shake, and more.

reddog81 · July 5, 2016, 09:49 AM

What does occansional use mean?

If for example 1,000 20k PSI will stretch the frame I imagine it won't take substantially more full strength 38 Special loads to do a similar amount of damage.

Bill DeShivs · July 5, 2016, 11:25 AM

Red Dog-
You need to do a LOT more research.
While 15% may not seem to be a lot to you, it means an awful lot when talking about ammunition pressure-especially when nearing maximum pressure.
You also need a better understanding of the mechanics of a gun.
Much of this has been explained in this thread.

SSA · July 5, 2016, 02:28 PM

Quote:

Horniday 125 gr low recoil H/P SELF DEFENSE

I don't see that load on Hornady's website.
If Hornady makes it, and it doesn't say +P, it's standard pressure.

briandg · July 5, 2016, 04:37 PM

You yourself referred to proof rounds. Every proof house has a protocol, for example, 40%over max for three rounds, followed by examining certain points of barrel and action for damage. If those boxes can all be checked as passing, the gun passes, and you are never to fire proof rounds again. That is one of the ways of saying "occasional use". Three times over the life of that firearm.

Every time a firearm is fired, there are a lot of places that are stretched or flexed, and they return to original condition. If the loads exceed the intended pressure levels, that normal flex is exceeded. A piece of steel that is stretched too hard will begin to wrap, or permanently lengthen. The steel can undergo many kinds of breakdown. After hundreds or thousands of over pressure loads, that firearm is going to have serious fatigue in several places. It may show with the barrel or receiver cracking, or the bolt lugs flattering. A revolver may become misaligned, the top strap ma stretche, the cylinder may blow out because of the steel breaking down after bulging outward hundreds of times. There's no fixed means of how a gun breaks down.

In fact, pressures are now measured using strain gauges. These films are attached to a barrel, and an electric current is passed through, and the gauge measures the temporary deformation of the steel when fired.

What do they mean by occasional use? This is what they mean.

"This pistol has been designed for standard ammo and will last forever with standard loads. It is capable of using pp loads, but it is not designed for it or strong enough, and it will not survive forever if you use other than standard ammo. So go ahead, you can use pp ammo sometimes, but we'd have to be complete idiots to tell you how many you can safely use."

If I owned a pistol from a good company marked for "occasional" PP rounds, I'd use no more than a box a year or so. A few to sight check, and then carry with them. If I used five or ten boxes a year, I'd be worried about wearing out the resilience of the materials.

I've already told you about an old man who damaged a wartime Smith with PP ammo. It happens.

July 2, 2016, 03:30 PM	#1
ZVP Senior Member Join Date: June 20, 2009 Posts: 1,102	Chamber pressures. 38 low recoil factory ammo? I' d like to fire Horniday 125 gr low recoil H/P SELF DEFENSE AMMO THROUGH MY Cobra .38 Derringer. My question is does this light bullet loads develop more pressure than Factory loaded 158 grain bullets? It dosen't say anything on the Horniday box about thesending being a high pressure load as the +P ammo does. Thanks again Dave

July 3, 2016, 06:41 AM	#2
briandg Senior Member Join Date: May 4, 2010 Posts: 5,468	standard pressure rounds are supposed to be that, they are not to exceed standard pressures as provided by SAAMI. Any pistol designed for standard rounds can fire a standard round. Now a +P round is a different thing. The plus is loaded to reach a significantly higher velocity and generates a significantly higher pressure, and this can only be fired in guns specifically suited for plus rounds. If your cartridges are not specifically listed as plus, they will be standard rounds. your handgun, sold as a .38 special is is supposed to be safe to fire with any standard .38 ammo. __________________ None.

July 4, 2016, 11:51 AM	#6
briandg Senior Member Join Date: May 4, 2010 Posts: 5,468	Red dog, even 15% is significant when you are talking about the differences in pistol s. Don't compare it to a .357, they aren't the same. You can warp aluminum frame revolvers. A friend inherited a pistol from his grandfather, with a few boxes of plus ammo. It had splits at the back of the barrel. That increase in pressure is significant, and that's why it's labeled as as high pressure, and they are labeled with warnings to use only in plus labeled guns.. __________________ None.

July 4, 2016, 07:35 PM	#8
briandg Senior Member Join Date: May 4, 2010 Posts: 5,468	Proof loads are fired a few times. Enough to be sure that there are no serious flaws in metal or materials, not to test the limitations of the design. There are handguns that are not supposed to be used with plus rounds. There are pistols that can't be used with heavy .45 using heavy rounds in weaker guns will eventually cause damage and using standard rounds in those same pistols is safe. You know, those are the rules, the people who make the things and set the standard. Failure to follow standards is dangerous. I'm not sure what your posts actually mean, but it kind of sounds like you were suggesting that it doesn't matter, and that people can use either one. That's not true. If you are telling the poster that he can use plus pressure rounds in any handgun made you are being very irresponsible and may lead to him either damaging his pistol or even getting hurt. __________________ None.

July 4, 2016, 11:21 PM	#9
reddog81 Senior Member Join Date: October 16, 2014 Location: Iowa Posts: 1,634	I'm not suggesting to use + P rounds in guns not rated for +P loads but realistically the 15% pressure difference isn't that much. If the gun doesnt have a 15% safety margin built into the design i'd be hesitant to shoot the gun much with any ammo. If a couple hundred rounds of +P is going to hurt a gun then realistically it's not that high quality of a gun to begin with Like I said previously 45 Colt +p is an entirely different animal Last edited by reddog81; July 4, 2016 at 11:28 PM.

July 4, 2016, 09:13 AM	#4
reddog81 Senior Member Join Date: October 16, 2014 Location: Iowa Posts: 1,634	I would imagine any low recoil load is going to have less pressure than an average 38 special load. Additionally +P loads don't develop what I would consider significant higher pressures and velocities. +P is only about 15% higher pressure and velocities. .357 Magnum develops significantly higher pressures and velocities. 38 special SAAMI pressure is 17,000 PSI +P is 20,000 .357 is 35,000 This holds true for 9mm and .45 ACP. However, 45 Colt is the exception to this rule and its +P pressure is almost double.

July 4, 2016, 10:02 AM	#5
Aguila Blanca Staff Join Date: September 25, 2008 Location: CONUS Posts: 18,460	The new "short barrel" rounds that have reached the marketplace recently are different from "standard" ammo in two respects. First, to counteract the loss of velocity due to powder burning in the barrel after the bullet has left, the "short barrel" ammo is loaded with faster-burning powder than standard self-defense ammo. Second, the bullets are designed to expand reliably at lower velocities than standard ammo. The faster powder very likely does result in slightly higher pressures than "standard" ammo of the same bullet weight, but probably not into the +P range. It may not be an increase in maximum pressure so much as a difference in the pressure rise curve. It's not marked +P so it isn't +P, and that should tell us that it's safe in any firearm that's designed to handle standard ammunition.

July 4, 2016, 12:41 PM	#7
reddog81 Senior Member Join Date: October 16, 2014 Location: Iowa Posts: 1,634	If I owned a gun that was going to fall apart after shooting a couple hundred rounds of +P ammo I'd be afraid to shoot any ammo in it. Any gun should be able to handle a proof load and not self destruct. If your gun is past that point I'd consider it a wall hanger.

July 5, 2016, 07:05 AM	#10
Aguila Blanca Staff Join Date: September 25, 2008 Location: CONUS Posts: 18,460	Okay, let's say +P represents a 15% increase over standard ammo of the same caliber. Let's also assume that you have a pistol with a 15% safety factor built in. As long as you always shoot standard ammo, you always have a 15% safety factor -- with every shot. Start shooting +P and now you have zero safety factor -- with every shot. But, hey ... it's only 15%, so it's no big deal. I own a couple of .38 Special revolvers of recent manufacture that are rated for standard ammo but not for +P. The manufacturer says they are safe for "occasional" use with +P, but a steady diet of +P will damage the guns. So I don't shoot +P through them, and I don't regard that as in any way reflecting on the quality of the firearm. If I buy a compact pickup that's rated to tow 5,000 pounds, is it a defect that it won't safely tow 6,000 pounds? No -- it wasn't designed to tow 6,000 pounds. Simple.

July 5, 2016, 08:17 AM	#11
reddog81 Senior Member Join Date: October 16, 2014 Location: Iowa Posts: 1,634	What does occasional use of +p mean? Either it can handle +P or it can't.

July 5, 2016, 09:49 AM	#13
reddog81 Senior Member Join Date: October 16, 2014 Location: Iowa Posts: 1,634	What does occansional use mean? If for example 1,000 20k PSI will stretch the frame I imagine it won't take substantially more full strength 38 Special loads to do a similar amount of damage.

July 5, 2016, 11:25 AM	#14
Bill DeShivs Senior Member Join Date: April 7, 2006 Posts: 10,981	Red Dog- You need to do a LOT more research. While 15% may not seem to be a lot to you, it means an awful lot when talking about ammunition pressure-especially when nearing maximum pressure. You also need a better understanding of the mechanics of a gun. Much of this has been explained in this thread. __________________ Bill DeShivs, Master Cutler www.billdeshivs.com

July 5, 2016, 04:37 PM	#16
briandg Senior Member Join Date: May 4, 2010 Posts: 5,468	You yourself referred to proof rounds. Every proof house has a protocol, for example, 40%over max for three rounds, followed by examining certain points of barrel and action for damage. If those boxes can all be checked as passing, the gun passes, and you are never to fire proof rounds again. That is one of the ways of saying "occasional use". Three times over the life of that firearm. Every time a firearm is fired, there are a lot of places that are stretched or flexed, and they return to original condition. If the loads exceed the intended pressure levels, that normal flex is exceeded. A piece of steel that is stretched too hard will begin to wrap, or permanently lengthen. The steel can undergo many kinds of breakdown. After hundreds or thousands of over pressure loads, that firearm is going to have serious fatigue in several places. It may show with the barrel or receiver cracking, or the bolt lugs flattering. A revolver may become misaligned, the top strap ma stretche, the cylinder may blow out because of the steel breaking down after bulging outward hundreds of times. There's no fixed means of how a gun breaks down. In fact, pressures are now measured using strain gauges. These films are attached to a barrel, and an electric current is passed through, and the gauge measures the temporary deformation of the steel when fired. What do they mean by occasional use? This is what they mean. "This pistol has been designed for standard ammo and will last forever with standard loads. It is capable of using pp loads, but it is not designed for it or strong enough, and it will not survive forever if you use other than standard ammo. So go ahead, you can use pp ammo sometimes, but we'd have to be complete idiots to tell you how many you can safely use." If I owned a pistol from a good company marked for "occasional" PP rounds, I'd use no more than a box a year or so. A few to sight check, and then carry with them. If I used five or ten boxes a year, I'd be worried about wearing out the resilience of the materials. I've already told you about an old man who damaged a wartime Smith with PP ammo. It happens. __________________ None.