H4831SC needs magnum primers?

A

aletheuo

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Hi guys - I've never used H4831SC in my 7mag before so this is a new one for me. I was at the range today and began experiencing some slight hangfires - just a 1/10 second from click to bang maybe but still a bit unnerving. Then... I got a total hangfire. I was lighting them with cci200 primers.

Tonight, I thought I'd pull the hangfire apart and dump the powder for reuse but the powder was all kinda chunked together (no, it wasn't compressed to start with). After some flicking of the side of the case the powder did finally come out but some sticks are golden yellowish color and some looks like normal. Almost 50-50. Is this partially burnt powder?

This primer batch is known to be good as a friend shot 1500 of them already. As an aside, I did end up handling them in my palm for a second or 2 (my hands aren't usually greasy either) because I had the wrong shell holder in my autoprime.

So - do you think it's because I handled them in my palm or do you think 61.5 grains H4831SC in a 7mag case needs a magnum primer? I've never had a need for a magnum primer before, but then again I haven't ever used cci 200 primers in my 7mag either, usually use wlr. But also the slowest powder I've used is imr4350.
 
aletheuo said:
So - do you think it's because I handled them in my palm or do you think 61.5 grains H4831SC in a 7mag case needs a magnum primer?
Click to expand...

Unless your hands were dripping with some kind of oil your hands had nothing to do with the hang/misfires.

If it were me I would get some Mag primers and see if the problem goes away.
 
61.5 Grains of H4831SC does not need a magnum primer to reliably light in the 7mm Mag. However, if temperatures were abnormally low, there may be virtue in choosing the hotter primer. Something else is at play here. Did the firing pin strike look normal? Is there any chance that some of those 7mm Mag cases had some moisture in them when they were charged? Did the misfire have an anvil in the primer? Just trying to eliminate some of the possibilities. Regards, Eagleye.
 
Eagleye said:
61.5 Grains of H4831SC does not need a magnum primer to reliably light in the 7mm Mag. However, if temperatures were abnormally low, there may be virtue in choosing the hotter primer. Something else is at play here. Did the firing pin strike look normal? Is there any chance that some of those 7mm Mag cases had some moisture in them when they were charged? Did the misfire have an anvil in the primer? Just trying to eliminate some of the possibilities. Regards, Eagleye.
Click to expand...

Temp was a balmy 2C. As to firing pin strikes, I've taken the bolt apart and cleaned it now as there was some (very little, but some) grit in there - that could have been it, too. I didn't deprime to check for anvil yet. But the clumping and miscoloring of the powder seems to tell me some sort of ignition tried to take place, yes? I've ruled out moisture.

I'll try again and prime with some wlrm's I have around - but dang it, I just bought a brick of the cci200's.
 
Regarding powder, it was a 7lb Higginson's box from a dealer. Was shooting 30-06 alongside using the same powder and primer lot with no problems. I think it was grit causing the pin to slow down just enough to make the primer have to think about going off. That said, a trip to the range is the only way I'm going to really know. Too bad work gets in the way of shooting. Thanks for all your input guys.
 
Didn't wash these cases. We'll see about the powder as BrotherJack has the other 3.5lbs and more cci200 primers. What makes me not suspect the powder is that I didn't shoot a group over 0.9 inches.
 
If bolt was gritty or if there was any grease on the firing pin, the cold temperture could have slowed the strike enough to cause problems. Rinse the bolt with brake cleaner and shoot it dry in winter, or with just a little Break Free.

It is shock that sets off a primer, not energy. A fast light firing pin might have the same energy as a heavy slow one - but only the fast one will work. If it slows down because of cold, it might not work.

propellent powder is a yellowish colour before it is coated with graphite. What you see is powder that has been blasted by a primer going off. For some reason the primer did not ignite the powder.

If you clean and rinse the firing pin and bolt interior, I expect you to get 100% ignition with the same ammo. We learn from experience. I urge you to clean and shoot same ammo again, so you learn that it was the dirty bolt - or, if it still does not work, you learn you need a hotter primer.

A Winchester primer is hotter and would be a good alround choice in that caliber. I do not use magnum primers in my 7 mag.

I once had a whole box of ammo go click-bang. It was a primer issue. A hotter primer solved it.
 
Ganderite - this is good advice to try the exact same combo again to nail down that it was the firing pin slowing down. And I did exactly what you said: brake cleaner and break free.
 
The powder granuiles are coated for two reasons. Number one is to slow down the burning rate of the powder, and number two is to stop static from becoming a serious problem. I believe that graphite accomplishes both.
Jamie, I would say that any time you are attempting to ignite over about 50 grains of powder, you should think of using a magnum powder to do so.
Mike
 
FWIW I use magnum primers in most of my rifles, from 30-06 up. Maybe unnecessary, but I was taught that it can provide more consistent ignition in really cold weather and as far as I can tell, it doesn't hurt anything.

+1 on degreasing the bolt/firing pin. That can cause you problems in the cold, but 2C isn't all that chilly.
 
OP here again - cleaned the bolt and gave it a bit of breakfree and took the same rounds out to the range today - all was fine for the first 13 rounds and then I got click...pause 1/10 sec then bang and so I put the other rounds in my pocket for 15 minutes to warm them up.

Put the next round in and click... nothing. Took it apart - same partially burnt chuncky yellowish powder. Primer strike was excellent. It appears clear to me that these cc200's can't effectively ignite this batch of h4831sc. Switching to same loads backed with wlrm's. I'll fire them straight out of the freezer (I'll put the bolt in the freezer, too) and will report results back.

Aleth
 
mike shickele said:
The powder granuiles are coated for two reasons. Number one is to slow down the burning rate of the powder, and number two is to stop static from becoming a serious problem. I believe that graphite accomplishes both.
Jamie, I would say that any time you are attempting to ignite over about 50 grains of powder, you should think of using a magnum powder to do so.
Mike
Click to expand...

You were right, Mike. I went with a frozen bolt and ammo to the range and got the same issue again... in two different rifles! Aha! It's the combination of the cci200 primers and a slightly lighter load of powder that caused it. What I did notice was that when I tipped my barrel up before shooting I didn't have a problem in either rifle.

I switched to Winchester LR's and Winchester LRM's and had excellent success. Note to self... use magnum primers with H4831SC and don't look back.

Thanks for all the help guys.
 
Graphite is used to disapate static electricity and to aid metering. it does not affect buring speed.

Speed is slowed down by surface treatment of (typically) DNT (di-nitro-tolulene - I think) A grain of powder has a large surface area that gets smaller as it burns. Since the vulume of gasses is getting larger as the bullet moves down the abrrel, this reduction in burning is the opposite of what is wanted.

Surface treatment with a retardent tries to make the burning speed more uniform.
 
Ganderite said:
Graphite is used to disapate static electricity and to aid metering. it does not affect buring speed.

Speed is slowed down by surface treatment of (typically) DNT (di-nitro-tolulene - I think) A grain of powder has a large surface area that gets smaller as it burns. Since the vulume of gasses is getting larger as the bullet moves down the abrrel, this reduction in burning is the opposite of what is wanted.

Surface treatment with a retardent tries to make the burning speed more uniform.
Click to expand...

I might be wrong, but I would suspect that anything that coats the granule slows down the initial burn. It may not be the primary reason that graphite is used, but it would be an added benefit.
Mike
 
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