couple .357 Mag questions

stump shooter · November 16, 2009, 03:06 PM

I have been working up some loads for my 4" GP100 using 158 XTP/HPs and H110. According to some research on factory ammo ballistics, 1200-1250 fps seems the norm for 158 grain jacketed bullets. Is this a good velocity to settle at? The manuals don't give a good expectation. They are plenty accurate anywhere over 1100 fps. I'm at 1200 fps+/- with 16.4 -16.5 gr.

Now, the real problem...I have had several misfires with CCI550s in only a few load workup rounds. They all go off after the second or even third strike, so I'm thinking seating is the problem. I have seen others have run into this using a hand prime tool but here's my situation:

I am using new Winchester brass and factory 1x brass and seat to what feels pretty hard and only getting flush to -.002 if I'm lucky. I have never had any other pistol primers fail, but these have me wondering if I need to uniform the stinking pockets on this particular brass?

Gaxicus · November 16, 2009, 03:44 PM

What does the primer look like after only one strike? If it looks softer than others, the primer may have slipped forward on the first strike. If it looks the same, and is deep and uniform, Id lean more toward bad primers.

I hate my RCBS hand primer tool but it does give you some "feel" as to whether the primer is seated all the way. I remember my boys had a hard time squeezing the tool enough sometimes to seat a primer on some 44mag we were loading. We had a couple failures but they were happening about every 90 rounds.

Revolvers usually dont have a hard time hitting the primer hard enough in my experience. The GP-100 has a good rep. A scored or gunked transfer bar could cause problems. Gunk/lint in the hammer channel maybe? How old is the gun?

joneb · November 16, 2009, 03:50 PM

I've had the same trouble with Win. brass for .357mag and CCI primers, if you can find some Federal primers they will seat much easier. Those CCI primers work well in Remington and Federal brass.

SwampYankee · November 16, 2009, 04:30 PM

I bought some new Winchester .45 Colt brass and had a really hard time seating some older CCI primers. Once I went to another brand and/or swaged the primer pocket, the problem was solved.

stump shooter · November 16, 2009, 07:57 PM

On the misfired primers the pin indent looks just like it would on one that goes off as normal. I don't think they're bad primers as they do go off after the second (and third on one occasion) strike.

I'm going to take a look at the brass, I might just run a PP uniformer through them. Like I said, I can't seat much below flush and this leads me to believe that the brass is just a pita batch. I've used a lot of WLP, F210, Wolf LR, and CCI500 in other cartridges and never had one misfire. I went ahead and picked up 2k of these 550s after hearing good things about them. I'll tinker with the brass and see.

Any thoughts on the velocities I'm getting with the 158 jacketed? Do they sound appropriate?

GP100man · November 17, 2009, 07:02 AM

Sounds like the problems I incounter when useing a 10# hammer spring.

I agree with tite pockets on WW cases & cci primers though .

SL1 · November 17, 2009, 07:49 AM

But, that isn't saying much. Velocities from revolvers can vary quite a bit, depending on such things as the individual cylinder gaps, chamber diameters, throat diameters, etc. The newest Speer manual has a comparison of identical handloads in 30 different guns that were all chambered for the .357 Magnum cartridge. Of those 30, 7 were revolvers that had 4" barrels. For the 158 grain handload, velocities ranged from 11015 to 1160fps, which is actually quite a small spread, compared to others in the table. For example, the same handloads in 9 different revolvers with 6" barrels gave a velocity spread from 1002 to 1284 fps. That isn't a typo, the spead is nearly 300 fps! (Speer doesn't say what the actual load was.)

So, for your particular revolver wit a 4" barrel, getting within 100 fps of the velocity value in your load data would be "OK" if the load data used the same barrel length.

For may years, Winchester published a load of 16.6 grains of WW-296 with Winchester MAGNUM small pistol primers and 158 grain jacketed (presumabley Winchester bullets.) Manuals at the time went higher still, but with different bullets and different primers. Winchester's magnum small pistol primers were supposedly made hotter especially for igniting WW-296, so that may account for some of the heavier loads from othe sources using other primers. And, of course, the bullets can make a difference, too.

When SAAMI published the peizo-electric standard, loads in manuals dropped some from what had been published for the CUP standard. Some people argue that the two standards give the same actual pressure, but those folks are clearly wrong. Less powder gives lower pressure. And arguments about changes in powders are not credible, because that would require that EVERY powder manufacturer would make ALL their pistol powders faster at the same time that SAAMI published the new standard. Some companies, such as Accurate, have shot new data still using the CUP standard (which is still accepted by SAAMI) because it allows for higher velcoties in the .357 and .44 magnums.

Whatever the real pressures are, the GP-100 was designed when CUP data was prevelant, and it is a good, strong gun. So, if you are loading for maximum power, then using some of the older load data should not be a problem in THAT gun.

SL1

stump shooter · November 17, 2009, 08:25 AM

Thanks everyone.

SL1, I ended up visiting factory ammo sites is to see what kind of ballistics are typical from their products and this is where I thought I should settle on the 1200-1250, it just seems like a good middle of the road load for a 4" revolver considering all the variables in firearms and fixtures in all the loading manuals that come into play. There also seems to be plenty of confidence in the GP100 and it's ability to handle hotter loads, so I am assuming I'm within reason

margiesex · November 17, 2009, 09:57 AM

Thank you for putting this up. I wish I could help you, but I have never had a CCI primer fail me...in heaven knows how many 1,000's - of all sizes both rifle and pistol.

I, too, load a 158 grain JSP - and I push it with a CCI mag. primer under 15 grains of Alliant 2400. Most accurate loads I have found, over I'd have to stop and count how many .357's, is always a fairly warm 2400 load. This particular matchup puts as many as you want from my daughter's Taurus 2"er inside a small fist at 7 yards - even better from my 3.5 inch Ruger.

I sure would be disappointed to find a problem with CCI's......

God bless.

Margiesex

And remember: Hug your God and your guns - 'cause he's coming for them both, and soon!

DMZX · November 17, 2009, 10:29 AM

Stump,

I have loaded a good deal of .357 Mags with 158 gr XTP's over H110. I have a pet load that is very accurate and comfortable to shoot in either my 4" GP-100 or my 3" 605.

I always use CCI Mag Small Pistol primers with mixed brass (mostly Win & Rem). I have been using the Hornady 7th edition and Hodgdon's online for my guides. 15.2 gr of H110 is my best load. Hornady list 12.7 as min and 15.6 as max, Hodgdon list 15.0 as min and 16.7 as max, so my 15.2 gr load is a moderate load and it feels that way.

I have never experienced any primer problems and I use a Lee hand tool to seat the primers.

My advice would be to be sure to clean the primer pockets and try another brand of primer such as Rem or Fed.

November 16, 2009, 03:06 PM	#1
stump shooter Member Join Date: March 23, 2008 Posts: 61	couple .357 Mag questions I have been working up some loads for my 4" GP100 using 158 XTP/HPs and H110. According to some research on factory ammo ballistics, 1200-1250 fps seems the norm for 158 grain jacketed bullets. Is this a good velocity to settle at? The manuals don't give a good expectation. They are plenty accurate anywhere over 1100 fps. I'm at 1200 fps+/- with 16.4 -16.5 gr. Now, the real problem...I have had several misfires with CCI550s in only a few load workup rounds. They all go off after the second or even third strike, so I'm thinking seating is the problem. I have seen others have run into this using a hand prime tool but here's my situation: I am using new Winchester brass and factory 1x brass and seat to what feels pretty hard and only getting flush to -.002 if I'm lucky. I have never had any other pistol primers fail, but these have me wondering if I need to uniform the stinking pockets on this particular brass?

November 16, 2009, 03:44 PM	#2
Gaxicus Senior Member Join Date: January 28, 2009 Location: USA Posts: 172	Primer multi strikes What does the primer look like after only one strike? If it looks softer than others, the primer may have slipped forward on the first strike. If it looks the same, and is deep and uniform, Id lean more toward bad primers. I hate my RCBS hand primer tool but it does give you some "feel" as to whether the primer is seated all the way. I remember my boys had a hard time squeezing the tool enough sometimes to seat a primer on some 44mag we were loading. We had a couple failures but they were happening about every 90 rounds. Revolvers usually dont have a hard time hitting the primer hard enough in my experience. The GP-100 has a good rep. A scored or gunked transfer bar could cause problems. Gunk/lint in the hammer channel maybe? How old is the gun?

November 17, 2009, 07:02 AM	#6
GP100man Senior Member Join Date: August 1, 2007 Location: Tabor City , NC. Posts: 1,969	Hammer Spring Sounds like the problems I incounter when useing a 10# hammer spring. I agree with tite pockets on WW cases & cci primers though . __________________ GP100man

November 17, 2009, 07:49 AM	#7
SL1 Senior Member Join Date: November 8, 2007 Posts: 2,001	Your velocities sound OK. But, that isn't saying much. Velocities from revolvers can vary quite a bit, depending on such things as the individual cylinder gaps, chamber diameters, throat diameters, etc. The newest Speer manual has a comparison of identical handloads in 30 different guns that were all chambered for the .357 Magnum cartridge. Of those 30, 7 were revolvers that had 4" barrels. For the 158 grain handload, velocities ranged from 11015 to 1160fps, which is actually quite a small spread, compared to others in the table. For example, the same handloads in 9 different revolvers with 6" barrels gave a velocity spread from 1002 to 1284 fps. That isn't a typo, the spead is nearly 300 fps! (Speer doesn't say what the actual load was.) So, for your particular revolver wit a 4" barrel, getting within 100 fps of the velocity value in your load data would be "OK" if the load data used the same barrel length. For may years, Winchester published a load of 16.6 grains of WW-296 with Winchester MAGNUM small pistol primers and 158 grain jacketed (presumabley Winchester bullets.) Manuals at the time went higher still, but with different bullets and different primers. Winchester's magnum small pistol primers were supposedly made hotter especially for igniting WW-296, so that may account for some of the heavier loads from othe sources using other primers. And, of course, the bullets can make a difference, too. When SAAMI published the peizo-electric standard, loads in manuals dropped some from what had been published for the CUP standard. Some people argue that the two standards give the same actual pressure, but those folks are clearly wrong. Less powder gives lower pressure. And arguments about changes in powders are not credible, because that would require that EVERY powder manufacturer would make ALL their pistol powders faster at the same time that SAAMI published the new standard. Some companies, such as Accurate, have shot new data still using the CUP standard (which is still accepted by SAAMI) because it allows for higher velcoties in the .357 and .44 magnums. Whatever the real pressures are, the GP-100 was designed when CUP data was prevelant, and it is a good, strong gun. So, if you are loading for maximum power, then using some of the older load data should not be a problem in THAT gun. SL1

November 17, 2009, 09:57 AM	#9
margiesex Senior Member Join Date: June 5, 2009 Location: Levittown, PA Posts: 210	Thanks for the info... Thank you for putting this up. I wish I could help you, but I have never had a CCI primer fail me...in heaven knows how many 1,000's - of all sizes both rifle and pistol. I, too, load a 158 grain JSP - and I push it with a CCI mag. primer under 15 grains of Alliant 2400. Most accurate loads I have found, over I'd have to stop and count how many .357's, is always a fairly warm 2400 load. This particular matchup puts as many as you want from my daughter's Taurus 2"er inside a small fist at 7 yards - even better from my 3.5 inch Ruger. I sure would be disappointed to find a problem with CCI's...... God bless. Margiesex And remember: Hug your God and your guns - 'cause he's coming for them both, and soon!

November 16, 2009, 03:50 PM	#3
joneb Senior Member Join Date: December 10, 2005 Location: Central , OR Posts: 1,888	I've had the same trouble with Win. brass for .357mag and CCI primers, if you can find some Federal primers they will seat much easier. Those CCI primers work well in Remington and Federal brass.

November 16, 2009, 04:30 PM	#4
SwampYankee Registration in progress Join Date: November 1, 2008 Location: I can be found on a number of other forums. Posts: 1,333	I bought some new Winchester .45 Colt brass and had a really hard time seating some older CCI primers. Once I went to another brand and/or swaged the primer pocket, the problem was solved.

November 16, 2009, 07:57 PM	#5
stump shooter Member Join Date: March 23, 2008 Posts: 61	On the misfired primers the pin indent looks just like it would on one that goes off as normal. I don't think they're bad primers as they do go off after the second (and third on one occasion) strike. I'm going to take a look at the brass, I might just run a PP uniformer through them. Like I said, I can't seat much below flush and this leads me to believe that the brass is just a pita batch. I've used a lot of WLP, F210, Wolf LR, and CCI500 in other cartridges and never had one misfire. I went ahead and picked up 2k of these 550s after hearing good things about them. I'll tinker with the brass and see. Any thoughts on the velocities I'm getting with the 158 jacketed? Do they sound appropriate?

November 17, 2009, 08:25 AM	#8
stump shooter Member Join Date: March 23, 2008 Posts: 61	Thanks everyone. SL1, I ended up visiting factory ammo sites is to see what kind of ballistics are typical from their products and this is where I thought I should settle on the 1200-1250, it just seems like a good middle of the road load for a 4" revolver considering all the variables in firearms and fixtures in all the loading manuals that come into play. There also seems to be plenty of confidence in the GP100 and it's ability to handle hotter loads, so I am assuming I'm within reason

November 17, 2009, 10:29 AM	#10
DMZX Senior Member Join Date: June 6, 2007 Location: E. Oregon Posts: 563	Stump, I have loaded a good deal of .357 Mags with 158 gr XTP's over H110. I have a pet load that is very accurate and comfortable to shoot in either my 4" GP-100 or my 3" 605. I always use CCI Mag Small Pistol primers with mixed brass (mostly Win & Rem). I have been using the Hornady 7th edition and Hodgdon's online for my guides. 15.2 gr of H110 is my best load. Hornady list 12.7 as min and 15.6 as max, Hodgdon list 15.0 as min and 16.7 as max, so my 15.2 gr load is a moderate load and it feels that way. I have never experienced any primer problems and I use a Lee hand tool to seat the primers. My advice would be to be sure to clean the primer pockets and try another brand of primer such as Rem or Fed.