Magnum primer problem

t*lesquirt said: Hi all----here's the story. Have been loading for my .300 Wby only and just picked up a lee loader for my .257 Roberts---made a few rounds using 38.4 grains of Hodgdon H4895 behind a Hornady 117 grain round nose---should be a mild load compared to the factory 120 grain +P's that I have been trying to get a decent grouping out of (no dice)----so the only primers I have here are Magnums and I search the posts and get the feeling that they should be okay with a mild load as pressure can increase slightly----first round seems okay---mild recoil and no signs of over pressures---next round was sticky on ejection and I notice some (blow by?) blackening around the primer seat----third round gun was very hard to open the action after firing ( Browning BLR '81 ) and when I do eject the case the spent primer appeard to have "welded" itself to the firing pin on the rifle and actually pulled free of the case and stayed in the action. primer seat was blackened up and sooty and I shut down after that untill I got some feedback from you guys----I will be pulling and dumping the rest of the rounds but want to know if this is only because of using the Magnum primers or am I also missing a different problem here? Thanks to all in advance----Rob.

s*nray said: Magnum primers can increase the pressures. They burn a bit hotter for a bit longer and are made to light hard to ignite powers and for cold weather shooting. H4895 doesn't need them. In any case, if you change any one component, you need to work up the load again.

303c*rbine said: Hi all----here's the story. Have been loading for my .300 Wby only and just picked up a lee loader for my .257 Roberts---made a few rounds using 38.4 grains of Hodgdon H4895 behind a Hornady 117 grain round nose---should be a mild load compared to the factory 120 grain +P's that I have been trying to get a decent grouping out of (no dice)----so the only primers I have here are Magnums and I search the posts and get the feeling that they should be okay with a mild load as pressure can increase slightly----first round seems okay---mild recoil and no signs of over pressures---next round was sticky on ejection and I notice some (blow by?) blackening around the primer seat----third round gun was very hard to open the action after firing ( Browning BLR '81 ) and when I do eject the case the spent primer appeard to have "welded" itself to the firing pin on the rifle and actually pulled free of the case and stayed in the action. primer seat was blackened up and sooty and I shut down after that untill I got some feedback from you guys----I will be pulling and dumping the rest of the rounds but want to know if this is only because of using the Magnum primers or am I also missing a different problem here? Thanks to all in advance----Rob. 38.6 of h4895 under the 117 grainer is the max load in the Hornady book and they don't even use a magnum primer.I would back down a couple grains at least and check your overall length.

pr*sper said: I doubt the magnum primers are the cause here. Yes, they are somewhat hotter, though not by enough to turn a safe load into what you're describing IMHO. Generally, from my own experiences, Magnum primers only add between .5 and 1 grain of extra oomph. Typically, one grain over max will not cause too much drama. The symptoms you describe are those of a grossly over-pressure load. Are you sure your scale is accurate? Are you using the right 4895 (IMR4895 is not the same as H4895)? Are your cases too long? Is the bullet seated too deeply, or jammed into the lands?

t*lesquirt said: I doubt the magnum primers are the cause here. Yes, they are somewhat hotter, though not by enough to turn a safe load into what you're describing IMHO. Generally, from my own experiences, Magnum primers only add between .5 and 1 grain of extra oomph. Typically, one grain over max will not cause too much drama. The symptoms you describe are those of a grossly over-pressure load. Are you sure your scale is accurate? Are you using the right 4895 (IMR4895 is not the same as H4895)? Are your cases too long? Is the bullet seated too deeply, or jammed into the lands? I didn't weigh the load---I am using the scoop that came with the lee loader----2.8cc leveled off and the brass is once fired from the same rifle I am loading for----using H4895 not IMR4895 and I have measured the rounds and have 2.75'' bang on----the bullets are seating just so the lands are visable---and they are seating easily---Rob.

303c*rbine said: I didn't weigh the load---I am using the scoop that came with the lee loader----2.8cc leveled off and the brass is once fired from the same rifle I am loading for----using H4895 not IMR4895 and I have measured the rounds and have 2.75'' bang on----the bullets are seating just so the lands are visable---and they are seating easily---Rob. When you say,just the lands are visible,do you mean they are noticeably engraving the bullets? If so,that will raise pressures significantly.

t*lesquirt said: By lands are we talking about the ring that runs around the bullet about halfway up?--if so the bullet is seating just to the bottom of the ring leaving the majority visible.

pr*sper said: no, that's the cannelure. If you're seating to that, you should be good. The lands are the grooves in the barrel. If you leave enough bullet sticking out of the brass, you can end up jamming the bullet into the grooves in the barrel, which will leave marks on the bullet if you chamber it. That doesn't seem to be the case here. I don't know why you're getting pressure signs here. It could be the primers, though I find that unlikely. It could also be just your rifle - every rifle is a law unto itself, which is why all load manuals advise you to start 10% low, and not to start with the 'max' load.

303c*rbine said: By lands are we talking about the ring that runs around the bullet about halfway up?--if so the bullet is seating just to the bottom of the ring leaving the majority visible. Is there any rifling marks on the bullet after you chamber and extract a live round? If so, then seating the bullet deeper is required. By the sounds of it you have high presures happening with the primer leaking as you stated.You should drop the charge and work up the load from the starting loads in your manual. Pix would help if you can post.

*nnovative said: telesquirt, The magnum primers are definitely not the problem. In fact they are highly recommended for most loads in the 300 Wby magnum, because they can ignite this large volume of powder in a timely and more consistent manner. Either of the 4895 powders are a very poor choice for the 300 Wby mag. You've got a huge case capacity there, and it will perform better and have MUCH lower chamber pressure with H4350 or H4831. Stick with the magnum primers. Try this and your pressure problem will be solved. I'll bet your accuracy also improves. I've always found the 300 Wby will shoot tighter groups with fairly HOT handloads. - Innovative

pr*sper said: I think he's talking about his 257 here, not the 300wby

mg34 said: not measuring the amount of powder going into the shell?? i consider the scoop not that good a measure. if you want good even reloads use a good powder scale and dont guess with the yellow scoop, you are asking for trouble.

*nnovative said: Oh yeah . . . . Sorry, I missed that. The 4895 is a great powder choice for the .257 Roberts. I still don't think the problem is the magnum primers, but I wouldn't choose to use them in the .257 Roberts, especially with 4895 powder. - Innovative

t*lesquirt said: telesquirt, The magnum primers are definitely not the problem. In fact they are highly recommended for most loads in the 300 Wby magnum, because they can ignite this large volume of powder in a timely and more consistent manner. Either of the 4895 powders are a very poor choice for the 300 Wby mag. You've got a huge case capacity there, and it will perform better and have MUCH lower chamber pressure with H4350 or H4831. Stick with the magnum primers. Try this and your pressure problem will be solved. I'll bet your accuracy also improves. I've always found the 300 Wby will shoot tighter groups with fairly HOT handloads. - Innovative I was talking about the .257 Bob---but thanks for the info---the load I was using with the H4895 seemed a bit anemic.

*nnovative said: MG34, You're sure right about the scoop method - very bad deal. Each powder has a different weight by volume, and you'll never know exactly what you're going to measure when you try different types of powder. Spend a few bucks and get a quality digital scale and a good powder measure. - Innovative

t*lesquirt said: not measuring the amount of powder going into the shell?? i consider the scoop not that good a measure. if you want good even reloads use a good powder scale and dont guess with the yellow scoop, you are asking for trouble. I am going to look for a scale----I have always used a lee loader and scoop for my .300 Wby and had no problems with that calibre---just by using the load data and recomended powder and bullets I have been able to have a lot of fun making my own ammo---that is why I am at a loss for the Bob---I thought loading for a smaller calibre was going to be a piece of cake! :confused:

*nnovative said: telesquirt, My number one powder choice would be H4831sc for hot loads in the .257 Roberts. - Innovative

*nnovative said: telesquirt, Check the Tech Tips section on my website, and you might get more motivated to working a little more on your handloads. It's addictive when you see your groups tighten up. http://www.larrywillis.com - Innovative

t*lesquirt said: telesquirt, Check the Tech Tips section on my website, and you might get more motivated to working a little more on your handloads. It's addictive when you see your groups tighten up. http://www.larrywillis.com - Innovative Thanks----I'll check it out!

t*lesquirt said: Thanks----I'll check it out! From your website----After each firing, I examine the primer for signs of excessive pressure. When the edge of the primer becomes completely flat, then it's time to stop increasing the load. I don't quite get what to look for when you say this----what is happening to the primer when it's edges flatten?

*nnovative said: telesquirt, I probably should add some pictures there to show "how much" is too much. Flat primers are the number one sign of chamber pressure going up. It's caused by case pressure increasing enough to blow the primer FLAT against the bolt. When it begins to change the shape at the edge of the primer, that indicates increasing chamber pressure. Compare the primers on your fired handloads with fired factory loads, and you'll get the idea of what safe loads look like. - Innovative

303c*rbine said: telesquirt, I probably should add some pictures there to show "how much" is too much. Flat primers are the number one sign of chamber pressure going up. It's caused by case pressure increasing enough to blow the primer FLAT against the bolt. When it begins to change the shape at the edge of the primer, that indicates increasing chamber pressure. Compare the primers on your fired handloads with fired factory loads, and you'll get the idea of what safe loads look like. - Innovative Sticky bolt lift with extraction problems along with flat primers all indicate too high of pressure.

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