.40 S&W and magnum primers?

geeboy7 · February 25, 2009, 01:15 AM

Hello I am new here and had a question that I was hoping someone could help me with. I recently reloaded about 75 rounds with speer 165gr. hollow points with 7.5 grains of hodgdon longshot powder. The problem is I just noticed I loaded them all with winchester small pistol magnum primers. So my question is is it safe to go ahead and shoot theses rounds through my XD or did I just waste 75 shots? Thanks.

SL1 · February 25, 2009, 08:27 AM

It's hard to know, especially with the information you left out.

I don't have Longshot in my QuickLOAD data, so I can't do any trial calcs for you.

Also, I don't have info on what bullet you are using, what data you are using, what the data COL is, what your COL is, what brand of primers you are using, etc.

Based on Hodgdon's manual, your load seems to be 40% of the way between start and max (there is only a 0.5 grain window from 7.3 to 7.8 grains for Longshot). That data is using Winchester SP primers, Sierra 165 JHPs and a COL of 1.125. Changing your COL by 0.020" can change your pressure by SEVERAL THOUSAND psi, so knowing that is critical. And, different bullet shapes change seating depth, so being able to adjust for seating dpeth differences is also critical for knowing pressure.

IF you were loading just as the Hodgdon data specified, you would already be at about 31,000 psi with Winchester standard primers. The SAAMI max pressure is 35,000. So, if your magnum primers increase pressure by about 12%, you would be at max. But, because I don't know the missing info for YOUR load, it is NOT safe for me to guess that it would be at 31,000 psi if you had used standard primers.

And, I really don't know what the pressure difference is between standard and magnum primers for THIS powder in THIS cartridge. Vague statements in some manuals about magnum primers being 5% or 10% "hotter" don't really mean "5% or 10% more pressure." They MIGHT mean "5% longer flame time" or " equavalent to 10% charge weight increase" or something else. They aren't specific about the change in pressure. And, remember this: increasing charge weight by 5% increases pressure by about twice that. For Lonshot with the Hodgdon 165 Sierra JHP data, increasinng the powder charge by 6.8% showes a pressure increase of 12.8%

Frankly, if it were me, I would pull the bullets, because there does not seem to be much margin in this load and the .40S&W has a reputation for being able to blow cases.

If I needed to use mag primers in my 40 S&W loads, I would want to start working-up the load from the point that it was not able to cycle the slide. I would stop when it was reliably functioning the slide and my chronograph said it was not getting more velocity than it should for that powder. I would NOT try to compare primer appearance to my standard primers, because magnum primer cups are stronger and only LOOK like they have experienced less pressure.

SL1

TreyNC · February 25, 2009, 10:19 AM

I would pull them and reuse materials. Maybe just loose the primers, not too bad.

SL1 · February 25, 2009, 01:31 PM

If you pull the bullets, you can reduce the powder charge and start working-up a load with the magnum primers that are still in the cases. Or, you could CAREFULLY decap the live primers, just as you do spent primers, and reuse them in other loads for whatever cartridge youbought them for. I just would not use those reclaimed primers for anything like self-defense or a match, where reliability is paramount.

If you decide to decap live primers, do it GENTLY while wearing eye and hearing protection. You probably won't need the protection, but it is best to be safe. (I have decapped live primers before without setting them off, and found that they all fired when used later.)

SL1

tom234 · February 25, 2009, 02:21 PM

I'd reuse the primers but reduce the load.

February 25, 2009, 01:15 AM	#1
geeboy7 Junior Member Join Date: February 25, 2009 Location: Centeral Texas Posts: 1	.40 S&W and magnum primers? Hello I am new here and had a question that I was hoping someone could help me with. I recently reloaded about 75 rounds with speer 165gr. hollow points with 7.5 grains of hodgdon longshot powder. The problem is I just noticed I loaded them all with winchester small pistol magnum primers. So my question is is it safe to go ahead and shoot theses rounds through my XD or did I just waste 75 shots? Thanks.

February 25, 2009, 08:27 AM	#2
SL1 Senior Member Join Date: November 8, 2007 Posts: 2,001	It's hard to know, especially with the information you left out. I don't have Longshot in my QuickLOAD data, so I can't do any trial calcs for you. Also, I don't have info on what bullet you are using, what data you are using, what the data COL is, what your COL is, what brand of primers you are using, etc. Based on Hodgdon's manual, your load seems to be 40% of the way between start and max (there is only a 0.5 grain window from 7.3 to 7.8 grains for Longshot). That data is using Winchester SP primers, Sierra 165 JHPs and a COL of 1.125. Changing your COL by 0.020" can change your pressure by SEVERAL THOUSAND psi, so knowing that is critical. And, different bullet shapes change seating depth, so being able to adjust for seating dpeth differences is also critical for knowing pressure. IF you were loading just as the Hodgdon data specified, you would already be at about 31,000 psi with Winchester standard primers. The SAAMI max pressure is 35,000. So, if your magnum primers increase pressure by about 12%, you would be at max. But, because I don't know the missing info for YOUR load, it is NOT safe for me to guess that it would be at 31,000 psi if you had used standard primers. And, I really don't know what the pressure difference is between standard and magnum primers for THIS powder in THIS cartridge. Vague statements in some manuals about magnum primers being 5% or 10% "hotter" don't really mean "5% or 10% more pressure." They MIGHT mean "5% longer flame time" or " equavalent to 10% charge weight increase" or something else. They aren't specific about the change in pressure. And, remember this: increasing charge weight by 5% increases pressure by about twice that. For Lonshot with the Hodgdon 165 Sierra JHP data, increasinng the powder charge by 6.8% showes a pressure increase of 12.8% Frankly, if it were me, I would pull the bullets, because there does not seem to be much margin in this load and the .40S&W has a reputation for being able to blow cases. If I needed to use mag primers in my 40 S&W loads, I would want to start working-up the load from the point that it was not able to cycle the slide. I would stop when it was reliably functioning the slide and my chronograph said it was not getting more velocity than it should for that powder. I would NOT try to compare primer appearance to my standard primers, because magnum primer cups are stronger and only LOOK like they have experienced less pressure. SL1

February 25, 2009, 10:19 AM	#3
TreyNC Member Join Date: February 13, 2007 Posts: 90	I would pull them and reuse materials. Maybe just loose the primers, not too bad.

February 25, 2009, 01:31 PM	#4
SL1 Senior Member Join Date: November 8, 2007 Posts: 2,001	If you pull the bullets, you can reduce the powder charge and start working-up a load with the magnum primers that are still in the cases. Or, you could CAREFULLY decap the live primers, just as you do spent primers, and reuse them in other loads for whatever cartridge youbought them for. I just would not use those reclaimed primers for anything like self-defense or a match, where reliability is paramount. If you decide to decap live primers, do it GENTLY while wearing eye and hearing protection. You probably won't need the protection, but it is best to be safe. (I have decapped live primers before without setting them off, and found that they all fired when used later.) SL1

February 25, 2009, 02:21 PM	#5
tom234 Senior Member Join Date: February 14, 2008 Location: Kansas Posts: 753	I'd reuse the primers but reduce the load.