40 S&W question

SW 586 · March 9, 2000, 07:56 PM

At present I reload only for 38/357. I would like to start reloading for the 40. I'm sure most of you are familiar with the warning in various manuals (Hodgdon in particular) stating that the barrel must fully support the cartridge in the chamber to prevent bulged or ruptured cases. My handgun is a S&W Model 410. How can I tell, or can anybody tell me, whether my gun meets this criteria. I didn't know whether to post this in this forum or the handgun forum, sorry.

Chad Young · March 9, 2000, 09:42 PM

The most commonly encountered guns with portions of the chamber unsupported is the Glock pistol. In order to promote proper feeding, the feed ramp is inletted such that a very small portion of the case is not fully supported. This is a large part of the reason Glock does not recommend reloads!

An easy way to see if your chamber is fully supported is to pull out the barrel and drop in a round. If the case is supported all the way around at the web, no problem. If I am not mistaken, yours should be fine.

Oh, for fun medium-power loads easy on the brass, try Winchester Super Field. I like 6.4 grains under a 165grain FMJ.

SW 586 · March 9, 2000, 10:19 PM

Chad,
I feel like an idiot for not doing that already. Sure enough, the case is fully encircled by the chamber with no inletting. Looks like I'm good to go. I'll try your load suggestion. Thanks for responding.
Bill

Pooch · March 11, 2000, 02:34 AM

funny so is my G23...hmmm how can that be, there suppose to be a big gap at 6:00 oclock, well maybe its overrrrr exagerated.

Hey maybe the 40 is pushed to the outer limits and any mistakes and boom, unlike 45, 10mm. (9 is cool cause it has lots of metal thickness at the chamber. Yep, I think this is it! Plastic is fine, its simple, it works! Ask a million cops!

Dont trash my Glock!

Banzai · March 13, 2000, 02:40 PM

This is from the Steyer M40 review on 1911.com:

Some manufacturers of 9mm pistols simply rebarrelled, modified the breechface
and put in a stiffer recoil spring to develop their initial .40 S&W pistols.
Since the .40/10mm bullet is bigger than a 9mm, the only way to get the .40 to
feed reliably was to create an intrusive feed ramp, and possibly an oversized
chamber to match. Thus the .40 S&W "Unsupported Chamber" was born. This was a
quick and dirty fix by some manufacturers to get to market fast.
Other manufacturers either started from scratch or went through the added
expense to redesign their 9's to safely handle the .40 with a well-supported
chamber that still feeds reliably. These types of .40 pistols are therefore
safer to use, whether you shoot factory ammo or reloaded ammo.
If you want to find out if your .40 has a well supported chamber, then do
this: Measure the diameter of the lower, most expanded part of some fired
brass. After the first measurement, rotate the brass slightly and measure it
again because the brass sometimes measures greater from a certain angle
because of the 6-o'clock chamber opening affect. If your brass measures .431
or greater, then your chamber is entering into unsupported territory. Also,
put a round into the barrel and look at the 6-o'clock position of the chamber
opening. If the thin part of the brass wall is exposed, or too much brass is
exposed, you have an unsupported chamber. "Both" of these measurements are
important to determine if your chamber is well supported or not. The greatest
brass expansion occurs when shooting full power loads.
The diameter of fully supported chanber brass usually measures around .427 -.429 for full
power loads. The Glock .40 can expand brass as much as .431 .433, which is a
huge difference.
Generally speaking, ammo and gun companies don't care about reloading safety
and case life. Some of the newer reloading manuals have strong warnings about
reloading for pistols with unsupported chambers, especially concerning high-
pressure cartridges.
One positive side effect of Glock's famous unsupported chamber and their
marketing omnipresence, is that some ammo companies have beefed up their .40
S&W brass so it has a better chance of surviving when fired in a Glock
chamber.

Tom

------------------
A "Miss" is the ultimate overpenetration!
You can never be too rich, too skinny, or too well armed!

March 9, 2000, 07:56 PM	#1
SW 586 Senior Member Join Date: March 9, 2000 Posts: 269	At present I reload only for 38/357. I would like to start reloading for the 40. I'm sure most of you are familiar with the warning in various manuals (Hodgdon in particular) stating that the barrel must fully support the cartridge in the chamber to prevent bulged or ruptured cases. My handgun is a S&W Model 410. How can I tell, or can anybody tell me, whether my gun meets this criteria. I didn't know whether to post this in this forum or the handgun forum, sorry.

March 9, 2000, 09:42 PM	#2
Chad Young Senior Member Join Date: September 20, 1999 Location: Gainesville, FL Posts: 601	The most commonly encountered guns with portions of the chamber unsupported is the Glock pistol. In order to promote proper feeding, the feed ramp is inletted such that a very small portion of the case is not fully supported. This is a large part of the reason Glock does not recommend reloads! An easy way to see if your chamber is fully supported is to pull out the barrel and drop in a round. If the case is supported all the way around at the web, no problem. If I am not mistaken, yours should be fine. Oh, for fun medium-power loads easy on the brass, try Winchester Super Field. I like 6.4 grains under a 165grain FMJ.

March 9, 2000, 10:19 PM	#3
SW 586 Senior Member Join Date: March 9, 2000 Posts: 269	Chad, I feel like an idiot for not doing that already. Sure enough, the case is fully encircled by the chamber with no inletting. Looks like I'm good to go. I'll try your load suggestion. Thanks for responding. Bill

March 11, 2000, 02:34 AM	#4
Pooch Member Join Date: March 3, 2000 Posts: 38	funny so is my G23...hmmm how can that be, there suppose to be a big gap at 6:00 oclock, well maybe its overrrrr exagerated. Hey maybe the 40 is pushed to the outer limits and any mistakes and boom, unlike 45, 10mm. (9 is cool cause it has lots of metal thickness at the chamber. Yep, I think this is it! Plastic is fine, its simple, it works! Ask a million cops! Dont trash my Glock!

March 13, 2000, 02:40 PM	#5
Banzai Senior Member Join Date: January 29, 2000 Posts: 275	This is from the Steyer M40 review on 1911.com: Some manufacturers of 9mm pistols simply rebarrelled, modified the breechface and put in a stiffer recoil spring to develop their initial .40 S&W pistols. Since the .40/10mm bullet is bigger than a 9mm, the only way to get the .40 to feed reliably was to create an intrusive feed ramp, and possibly an oversized chamber to match. Thus the .40 S&W "Unsupported Chamber" was born. This was a quick and dirty fix by some manufacturers to get to market fast. Other manufacturers either started from scratch or went through the added expense to redesign their 9's to safely handle the .40 with a well-supported chamber that still feeds reliably. These types of .40 pistols are therefore safer to use, whether you shoot factory ammo or reloaded ammo. If you want to find out if your .40 has a well supported chamber, then do this: Measure the diameter of the lower, most expanded part of some fired brass. After the first measurement, rotate the brass slightly and measure it again because the brass sometimes measures greater from a certain angle because of the 6-o'clock chamber opening affect. If your brass measures .431 or greater, then your chamber is entering into unsupported territory. Also, put a round into the barrel and look at the 6-o'clock position of the chamber opening. If the thin part of the brass wall is exposed, or too much brass is exposed, you have an unsupported chamber. "Both" of these measurements are important to determine if your chamber is well supported or not. The greatest brass expansion occurs when shooting full power loads. The diameter of fully supported chanber brass usually measures around .427 -.429 for full power loads. The Glock .40 can expand brass as much as .431 .433, which is a huge difference. Generally speaking, ammo and gun companies don't care about reloading safety and case life. Some of the newer reloading manuals have strong warnings about reloading for pistols with unsupported chambers, especially concerning high- pressure cartridges. One positive side effect of Glock's famous unsupported chamber and their marketing omnipresence, is that some ammo companies have beefed up their .40 S&W brass so it has a better chance of surviving when fired in a Glock chamber. Tom ------------------ A "Miss" is the ultimate overpenetration! You can never be too rich, too skinny, or too well armed!