Chamber pressure

Jonzeey02 · January 25, 2015, 03:58 PM

Hi guys I have a question regarding chamber pressure in general. I was looking into getting a S&W Shield in a.40 caliber then I heard some of the shields was blowing up due to ammunition being to "hot" for the gun so I was wondering since I reload S&W .40 where can I find info on how much pressure is in each casing? Is that info in my manual which currently I have the hornady 8th edition I'm using right now. Am I over looking it? I understand the .40 S&W in general can stand up to 35000 psi of pressure according to saami so I was wondering how much pressure was in a shell. Currently I'm reloading 200 GN hornady xtp bullets with 5.9 GN of no. 5 powder. I just don't want to make my reloads too hot which I stay below the recommended max load. Thanks guys.

jwrowland77 · January 25, 2015, 04:00 PM

You can't unless you have a pressing testing chamber that will tell you.

As long as you stay within book you should be good. If worried, stay on low end as long as it's cycling.

Since I don't shoot pistol much, I start at min and stay there unless I'm having issues with cycling, then I'll bump it up .1 or .2 grains until it cycles reliably.

You could always read over the SAAMI documents for your caliber.

Jonzeey02 · January 25, 2015, 04:03 PM

Thanks

steve4102 · January 25, 2015, 04:30 PM

Hornady does not list pressures, but Lyman and all the powder manufacturers/distributors do.

kraigwy · January 25, 2015, 06:11 PM

The best tool I've found for estimating pressure is "QuickLoad". I found it highly accurate comparing the velocity's it gives to my choreograph.

Its great for "What If's", i.e. I'm using x grs. of power, what would happen if I used X+, to both velocity and pressure. Or what would happen if I changed for X to Y powder. Or, what would happen if I switched brand X bullet with a brand Y bullet of the same weight.

If one is really serious with his reloading, its a program well worth having.

Sevens · January 26, 2015, 01:11 AM

The .40 S&W developed the best reputation in the history of handgunning for KABOOMS, more than anything else before or since. This was due to a number of factors -- some known, and as always with handloaders... some unknown as the evidence often gets destroyed.

It is my position that many kabooms in the history of the .40 S&W chambering have been due to unintended and unnoticed bullet setback, where the brass simply doesn't have a solid grip on that slug, the slug gets pushed deeper in to the brass case (and this is not known as the gun goes in to battery and it is not seen by the shooter) and in concert with the many other struggles that have plagued the .40 S&W, it is this situation that is one of the great causes for catastrophic incidents.

I have no proof, this is merely my theory. But I believe it behooves any handloader to pay extremely close attention to and give much care to case mouth tension. How to get it, how to -NOT- corrupt it and how to be well aware of it's importance.

As to "what kind of pressure is happening in there...", the answers given are correct -- no way to know without expensive equipment AND sticking to published factory data is safe AND it is most likely that any known factory ammo is simply running very close to 35k PSI, not much under and certainly not over that. They can't make it much under 35k PSI for fear that customer guns simply won't run reliably without the expected pressure. And they can't make it over 35k PSI because they are SAAMI members and they stick to the industry standard just as the gun manufacturers do.

January 25, 2015, 03:58 PM	#1
Jonzeey02 Member Join Date: August 22, 2012 Posts: 29	Chamber pressure Hi guys I have a question regarding chamber pressure in general. I was looking into getting a S&W Shield in a.40 caliber then I heard some of the shields was blowing up due to ammunition being to "hot" for the gun so I was wondering since I reload S&W .40 where can I find info on how much pressure is in each casing? Is that info in my manual which currently I have the hornady 8th edition I'm using right now. Am I over looking it? I understand the .40 S&W in general can stand up to 35000 psi of pressure according to saami so I was wondering how much pressure was in a shell. Currently I'm reloading 200 GN hornady xtp bullets with 5.9 GN of no. 5 powder. I just don't want to make my reloads too hot which I stay below the recommended max load. Thanks guys.

January 25, 2015, 04:00 PM	#2
jwrowland77 Senior Member Join Date: March 23, 2012 Location: Conway, Arkansas Posts: 1,398	Chamber pressure You can't unless you have a pressing testing chamber that will tell you. As long as you stay within book you should be good. If worried, stay on low end as long as it's cycling. Since I don't shoot pistol much, I start at min and stay there unless I'm having issues with cycling, then I'll bump it up .1 or .2 grains until it cycles reliably. You could always read over the SAAMI documents for your caliber.

January 26, 2015, 01:11 AM	#6
Sevens Senior Member Join Date: July 28, 2007 Location: Ohio Posts: 11,775	The .40 S&W developed the best reputation in the history of handgunning for KABOOMS, more than anything else before or since. This was due to a number of factors -- some known, and as always with handloaders... some unknown as the evidence often gets destroyed. It is my position that many kabooms in the history of the .40 S&W chambering have been due to unintended and unnoticed bullet setback, where the brass simply doesn't have a solid grip on that slug, the slug gets pushed deeper in to the brass case (and this is not known as the gun goes in to battery and it is not seen by the shooter) and in concert with the many other struggles that have plagued the .40 S&W, it is this situation that is one of the great causes for catastrophic incidents. I have no proof, this is merely my theory. But I believe it behooves any handloader to pay extremely close attention to and give much care to case mouth tension. How to get it, how to -NOT- corrupt it and how to be well aware of it's importance. As to "what kind of pressure is happening in there...", the answers given are correct -- no way to know without expensive equipment AND sticking to published factory data is safe AND it is most likely that any known factory ammo is simply running very close to 35k PSI, not much under and certainly not over that. They can't make it much under 35k PSI for fear that customer guns simply won't run reliably without the expected pressure. And they can't make it over 35k PSI because they are SAAMI members and they stick to the industry standard just as the gun manufacturers do. __________________ *Attention Brass rats and other reloaders:* I really need .327 Federal Magnum brass, no lot size too small. Tell me what caliber you need and I'll see what I have to swap. PM me and we'll discuss.

January 25, 2015, 04:03 PM	#3
Jonzeey02 Member Join Date: August 22, 2012 Posts: 29	Thanks

January 25, 2015, 04:30 PM	#4
steve4102 Senior Member Join Date: December 23, 2005 Location: Minnesota Posts: 2,968	Hornady does not list pressures, but Lyman and all the powder manufacturers/distributors do.

January 25, 2015, 06:11 PM	#5
kraigwy Senior Member Join Date: June 16, 2008 Location: Wyoming Posts: 11,060	The best tool I've found for estimating pressure is "QuickLoad". I found it highly accurate comparing the velocity's it gives to my choreograph. Its great for "What If's", i.e. I'm using x grs. of power, what would happen if I used X+, to both velocity and pressure. Or what would happen if I changed for X to Y powder. Or, what would happen if I switched brand X bullet with a brand Y bullet of the same weight. If one is really serious with his reloading, its a program well worth having.