use of magnum small pistol primers

karday · December 10, 2009, 10:28 PM

Given the shortage of primers I wanted to know if anyone has a load for 40 S&W using Magnum small pistol primers. Most suppliers will not take back orders and those that do are guessing 8 weeks minumum waiting for many items especially primers.

frumious · December 10, 2009, 10:44 PM

It will be interesting what people say. I use magnum small pistol primers in 9mm and they work fine...but I don't load anywhere near max loads. Just barely over starting loads, in fact.

40S&W though...man, I respect that cartridge. So much in fact that I sold my Glock 22 in order to not be tempted to reload 40S&W at all. 'Course the Glock 40S&W seems to be regarded as a particularly perilous proposition for a person who prefers plumbum (me) so it wasn't just the cartridge.

I'd say don't do it.

-cls

**Unclenick** · December 10, 2009, 10:47 PM

Welcome to the forum.

The primers will fit. The effect they will have is not entirely predictable. The first assumption is they will raise pressure because that's what magnum primers are for; to raise the case pressure that the powder begins burning in, and in turn, that raises peak pressure. If you are using a powder that leaves a lot of empty space, it may actually improve performance consistency. However, because of the starting pressure increase, you want to reduce your powder charge 10% and work it back up until it matches the performance you got from standard primers in your gun. A chronograph is a big help with this.

The other thing that can happen is the higher primer pressure unseats the bullet and pushes it forward before the powder gets burning thoroughly. That increases the space the powder burns in and actually lowers pressure. It can make muzzle velocity somewhat erratic. Again, a chronograph is a good way to tell if this is happening.

So, operate on the assumption pressure will rise, lowering your powder charge to start the experiment. In the end it may raise or lower pressure, may improve or deteriorate muzzle velocity consistency. You just have to try that to see? Provided you make the initial charge reduction, this is perfectly safe to do.

Foxbat · December 10, 2009, 11:21 PM

I have done the .40 with both regular and magnum CCI primers, and did not see any measurable difference. But the advice to back off a bit at first is good one, just in case, as different powders might react differently.

fishman35 · December 11, 2009, 04:03 PM

I shot them for a while when primer was tough to get. I shot about 3,000 rounds for a 9MM this summer and they were a bit hot, depending on what power type and load I used. I mostly use HP-38 for my pistols.

My cops buddies way up north state they use them for sub freezing temperatures when the gun is outside on their hip for an extended period of time. Not sure how much truth there is to that.

December 10, 2009, 10:28 PM	#1
karday Junior Member Join Date: December 10, 2009 Location: Maryland Posts: 2	use of magnum small pistol primers Given the shortage of primers I wanted to know if anyone has a load for 40 S&W using Magnum small pistol primers. Most suppliers will not take back orders and those that do are guessing 8 weeks minumum waiting for many items especially primers.

December 10, 2009, 10:47 PM	#3
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,738	Welcome to the forum. The primers will fit. The effect they will have is not entirely predictable. The first assumption is they will raise pressure because that's what magnum primers are for; to raise the case pressure that the powder begins burning in, and in turn, that raises peak pressure. If you are using a powder that leaves a lot of empty space, it may actually improve performance consistency. However, because of the starting pressure increase, you want to reduce your powder charge 10% and work it back up until it matches the performance you got from standard primers in your gun. A chronograph is a big help with this. The other thing that can happen is the higher primer pressure unseats the bullet and pushes it forward before the powder gets burning thoroughly. That increases the space the powder burns in and actually lowers pressure. It can make muzzle velocity somewhat erratic. Again, a chronograph is a good way to tell if this is happening. So, operate on the assumption pressure will rise, lowering your powder charge to start the experiment. In the end it may raise or lower pressure, may improve or deteriorate muzzle velocity consistency. You just have to try that to see? Provided you make the initial charge reduction, this is perfectly safe to do. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

December 10, 2009, 10:44 PM	#2
frumious Senior Member Join Date: May 13, 2009 Location: Carrollton TX Posts: 523	It will be interesting what people say. I use magnum small pistol primers in 9mm and they work fine...but I don't load anywhere near max loads. Just barely over starting loads, in fact. 40S&W though...man, I respect that cartridge. So much in fact that I sold my Glock 22 in order to not be tempted to reload 40S&W at all. 'Course the Glock 40S&W seems to be regarded as a particularly perilous proposition for a person who prefers plumbum (me) so it wasn't just the cartridge. I'd say don't do it. -cls

December 10, 2009, 11:21 PM	#4
Foxbat Senior Member Join Date: January 13, 2008 Posts: 367	I have done the .40 with both regular and magnum CCI primers, and did not see any measurable difference. But the advice to back off a bit at first is good one, just in case, as different powders might react differently.

December 11, 2009, 04:03 PM	#5
fishman35 Junior Member Join Date: May 1, 2009 Posts: 8	I shot them for a while when primer was tough to get. I shot about 3,000 rounds for a 9MM this summer and they were a bit hot, depending on what power type and load I used. I mostly use HP-38 for my pistols. My cops buddies way up north state they use them for sub freezing temperatures when the gun is outside on their hip for an extended period of time. Not sure how much truth there is to that.