40 case thickness?

stevieray · May 17, 2010, 01:21 AM

Had a blowout with my S&W p99. Since, I have been soaking up all the info on unsupported 40 cal case heads....and reloads. I had the worst of both worlds...bad brass (over used) I aquired also. What I am looking for is; specs on the alowable thickness of the brass. I have a tube micrometer, but no specs to work off of. I would appreciate any help, Thanks
Dan

Shoney · May 17, 2010, 05:27 AM

stevieray
Dan

WELCOME TO TFL!

I measured several cases each of Federal, W-W, and R-P 40 SW brass. I took the measurements near the mouth of the cases, because the case begins to taper as it get closer to the base.

All were 0.010", with the exception of one R-P case which was 0.0086". They increase in thickness gradually to 0.012" ata bout the center of the cases, then expanded rapidly to 0.030" at about 0.5" from the mouth (this was more of a guess as my calipers are not designed to thead thickness accurately beyond 0.35" into the case).

Having given you this information, I fail to see how it can be used meaningfully. I would be more curious as to what caused the blowout and correct that problem. What brass, what powder, what load, what bullet brand/make/weight. Besides exceeding the maximum charge, there are several other factors that may have caused it.

I've been loading 40SW for over 10 years and have fired well over 50k, and loaded many more for the family. I have never had a blowout nor any troubles

stevieray · May 17, 2010, 12:25 PM

thanks for the reply-
I was using 180g fmj, with 6.4g Unique. Some of the brass developed large bulges (in the shape of the feed ramp), others were normal. I had been acquiring brass from several places, not knowing the history. I am thinking some were reloaded too many times, and the brass became too thin. I took the gun and brass / ammo to my gunsmith....he described as a "perfect storm" between the old brass and an unsupported case head. My thoughts, were, in the future, if I had specs to go off of, I could measure the brass thickness and look for failures before they happen......any thoughts??
Dan

Shoney · May 17, 2010, 02:21 PM

Quote:

stevieray wrote:
I was using 180g fmj, with 6.4g Unique.

According to my data, that load is right at max, which opens up numerous things that can get you into trouble.

I have rarely found max loads to give the best accuracy with any bullet/powder combination in my 40SW's.

1. What primer were you using?

2. What were your accuracy results at the lower grain weights as you worked up to maximum charge?

3. What was your AOL? Was the neck tension enough to keep the bullet from setting back? (Bullets that get pushed back during recoil can up the pressure to dangerous levels.)

4. Have you checked your weapon to make sure it does not fire out of battery? (If your weapon will fire when the cartridge is not fully chambered, that could be the cause of some of your brass to bulge at the webbing.)

Clark · May 17, 2010, 02:43 PM

I have spend a lot of hours finding the threshold of case bulge over the feed ramp in many semi auto handguns and in 25acp, 32acp, 7.62x25mm, .380, 9x19mm, 9x23mm, 40 sw, 10mm, and 45acp.

The 40sw tests I have done were with mixed once fired brass from Scharch 10 years ago when it was $40/1000 delivered.
http://www.scharch.com/proddetail.ph...B040S%26WCY-5C

I tested with a barrel with a feed ramp intruding .235" with case webs .180" leaving .055" of unsupported case wall.
From brand to brand, from shot to shot, the threshold of case bulge, and even the sized of the bulge is remarkably consistent.

For this to happen I need to load consistently, which I try to do.
But it also means that the brass wall thickness in the unsupported area, the powder, and the bullets must be consistent.

SQUAREKNOT · May 18, 2010, 09:32 PM

A max load of Unique is risky as it does not meter well at all. My powder dump threw almost a full grain from load to load. I also found Winchester primers a pain as the are FOR STANDARD OR MAGNUM USE. I was flattening primers at low load levels for what ever reason. When I switched to CCI or Remington the problem stopped.
all FWIW

bullspotter · May 19, 2010, 10:24 PM

I would back that load off, Im no pro reloader but have learnd alot about the 40. I also use unique. I found the load data to be on the hot side, Im shooting 165 gr mt gold bullets. I started at min and worked my way up, I was getting bulged brass before I got to the max load with a G22 and lone wolf barrel. I also have a freind that runs unique and he had 4 blowouts in a G23 with lone wolf barrel. After running my loads though a chrono, I found I was still way above the published velocity, Im loading below the starting load for a 165 gr bullet, Chrono shows im right with factory ammo on velocity.

Also make sure your not getting any setback, I have found the r-p brass seems to be a bit thinner then others, I refuse to use it, all I use is winchester. All my brass is range p/u I didnt start with any new. I did buy one box of factory for testing.

stevieray · May 20, 2010, 02:33 PM

thanks for all of the info!

My data showed that the recipe was middle of the road, apparantly not. Accuracy was fine, but I do mostly close quarters stuff with that gun. Either way, I am purging all of my used 40 brass and starting fresh. I will take all of the suggestions seriously.
thanks again

May 17, 2010, 01:21 AM	#1
stevieray Junior Member Join Date: May 17, 2010 Posts: 3	40 case thickness? Had a blowout with my S&W p99. Since, I have been soaking up all the info on unsupported 40 cal case heads....and reloads. I had the worst of both worlds...bad brass (over used) I aquired also. What I am looking for is; specs on the alowable thickness of the brass. I have a tube micrometer, but no specs to work off of. I would appreciate any help, Thanks Dan

May 17, 2010, 05:27 AM	#2
Shoney Senior Member Join Date: February 21, 2002 Location: Transplanted from Montana Posts: 2,311	stevieray Dan WELCOME TO TFL! I measured several cases each of Federal, W-W, and R-P 40 SW brass. I took the measurements near the mouth of the cases, because the case begins to taper as it get closer to the base. All were 0.010", with the exception of one R-P case which was 0.0086". They increase in thickness gradually to 0.012" ata bout the center of the cases, then expanded rapidly to 0.030" at about 0.5" from the mouth (this was more of a guess as my calipers are not designed to thead thickness accurately beyond 0.35" into the case). Having given you this information, I fail to see how it can be used meaningfully. I would be more curious as to what caused the blowout and correct that problem. What brass, what powder, what load, what bullet brand/make/weight. Besides exceeding the maximum charge, there are several other factors that may have caused it. I've been loading 40SW for over 10 years and have fired well over 50k, and loaded many more for the family. I have never had a blowout nor any troubles __________________ I pledge allegiance to the Flag - - -, and to the Republic for which it stands….Our Forefathers were brilliant for giving us a Republic, not a democracy! Do you know the difference??? and WHY?http://www.wallbuilders.com/LIBissue...les.asp?id=111

May 17, 2010, 12:25 PM	#3
stevieray Junior Member Join Date: May 17, 2010 Posts: 3	thanks for the reply- I was using 180g fmj, with 6.4g Unique. Some of the brass developed large bulges (in the shape of the feed ramp), others were normal. I had been acquiring brass from several places, not knowing the history. I am thinking some were reloaded too many times, and the brass became too thin. I took the gun and brass / ammo to my gunsmith....he described as a "perfect storm" between the old brass and an unsupported case head. My thoughts, were, in the future, if I had specs to go off of, I could measure the brass thickness and look for failures before they happen......any thoughts?? Dan

May 17, 2010, 02:43 PM	#5
Clark Senior Member Join Date: December 4, 1999 Location: WA, the ever blue state Posts: 4,678	I have spend a lot of hours finding the threshold of case bulge over the feed ramp in many semi auto handguns and in 25acp, 32acp, 7.62x25mm, .380, 9x19mm, 9x23mm, 40 sw, 10mm, and 45acp. The 40sw tests I have done were with mixed once fired brass from Scharch 10 years ago when it was $40/1000 delivered. http://www.scharch.com/proddetail.ph...B040S%26WCY-5C I tested with a barrel with a feed ramp intruding .235" with case webs .180" leaving .055" of unsupported case wall. From brand to brand, from shot to shot, the threshold of case bulge, and even the sized of the bulge is remarkably consistent. For this to happen I need to load consistently, which I try to do. But it also means that the brass wall thickness in the unsupported area, the powder, and the bullets must be consistent.

May 18, 2010, 09:32 PM	#6
SQUAREKNOT Senior Member Join Date: July 16, 2008 Posts: 263	A max load of Unique is risky as it does not meter well at all. My powder dump threw almost a full grain from load to load. I also found Winchester primers a pain as the are FOR STANDARD OR MAGNUM USE. I was flattening primers at low load levels for what ever reason. When I switched to CCI or Remington the problem stopped. all FWIW

May 19, 2010, 10:24 PM	#7
bullspotter Senior Member Join Date: November 2, 2008 Location: Montana Posts: 308	I would back that load off, Im no pro reloader but have learnd alot about the 40. I also use unique. I found the load data to be on the hot side, Im shooting 165 gr mt gold bullets. I started at min and worked my way up, I was getting bulged brass before I got to the max load with a G22 and lone wolf barrel. I also have a freind that runs unique and he had 4 blowouts in a G23 with lone wolf barrel. After running my loads though a chrono, I found I was still way above the published velocity, Im loading below the starting load for a 165 gr bullet, Chrono shows im right with factory ammo on velocity. Also make sure your not getting any setback, I have found the r-p brass seems to be a bit thinner then others, I refuse to use it, all I use is winchester. All my brass is range p/u I didnt start with any new. I did buy one box of factory for testing.

May 20, 2010, 02:33 PM	#8
stevieray Junior Member Join Date: May 17, 2010 Posts: 3	thanks for all of the info! My data showed that the recipe was middle of the road, apparantly not. Accuracy was fine, but I do mostly close quarters stuff with that gun. Either way, I am purging all of my used 40 brass and starting fresh. I will take all of the suggestions seriously. thanks again