Winchester LP primer split in 44 mag

[totaldla]

Had two WLP primers split in a 329pd with a max load of Enforcer. The same load with CCI350's was fine.

Pitting at the firing pin:

Case view:
https://sites.google.com/site/hobbyh...imer_split.JPG
Zoomed in:
https://sites.google.com/site/hobbyh...imer_split.JPG

Any guesses why the Winchester primers let go?

https://sites.google.com/site/hobbyh...s-w-329pd-info

[dahermit]

The reason your primers are "blown", is that you exceeded the limit for your gun, powder, case, primer. It is likely that the cases were hard to extract also? Did you ever hear: "Start with the recommended minimum weight of powder and work up slowly while looking for signs of excess pressure."? Well, you just had a sign of excess pressure.

[Loader9]

Assuming you used Winchester Large Pistol primers, you used the wrong primers according to the data supplied by Ramshot. They clearly recommend a large magnum pistol primer. If you use a primer of too low brisance, you'll get near hangfire condition and gross over pressure loads. Kinda like what you have.

http://www.ramshot.com/powders/loadg...de%20V4.3b.pdf

The data shows a Federal 155 primer which is a magnum primer.

[totaldla]

Cases weren't hard to extract - fell out like normal.

The Winchester LP is for "standard and magnum" loads - printed right on the box. And WLPs have been tested and found to be just as hot as "magnum" primers. However, WLP's do have a soft cup.

I don't understand how a low brisance causes high pressure, but I'll leave that to the experts.

Yep, I was working up a load and that was the limit. Thanks for the info.

[AlaskaMike]

I don't agree that this is clear evidence of excessive pressure--the primer still has a nice radius around the edge.

I'd send that photo and your load info to someone at Winchester (Olin? Not sure who makes Winchester branded primers these days) along with the lot number of your primers and ask them for their opinion.

I'm leaning towards a primer problem, especially since you mention that the same load with CCI 350's was fine.

Mike

[amathis]

SO you had a Max load that worked well with CCI350's and you changed a component and you didn't start over developing the load?

Whenever we change a component ESPECIALLY so close to max ALWAYS reduce the load and work up a new one.

My rant is over.

Glad you are still here to ask why this happened.

You tried this with 2 you said? I wonder if Olin would trade you a pack of primers. almost strikes me as a bad batch of primers kinda like the cup wasn't strong enough. Have you used these primers in the same lot in other loads?

[totaldla]

Yes, yes I know I committed the sin of not working back up. I was lulled into complacency by the low velocities, easy case extraction and lack of flattened primers.

[Unclenick]

This is not at all a high pressure load. Both the Ramshot data and QuickLOAD put it about 26 Kpsi when all the data is properly tweaked for matching barrel length and velocity. Enforcer is actually a slow powder for the application, and burns very inefficiently in it. That is part of the problem, since spherical propellants often have ignition issues in low pressure loads. The WFN bullet form is stubby, so there is about 25% empty space in the case, which exacerbates slow ignition.

The outer edges of the primer are not mushroomed, but they have sharp edges at the corners where the piercing is located. They correspond to the chamfer in the firing pin bushing, which could be expected to cause primer cratering in a high pressure load. Further, I notice the whole primer looks somewhat concave or inverted cone shaped around the pin indentation, another low pressure sign.

Further confirmation of the low pressure problem comes from the fact the velocity prediction from QuickLOAD matches the published pressure and velocity data for a 8.275" barrel, but shows 200 fps greater velocity with a 4" barrel achieving the same peak pressure with 20 grains of Enforcer than Totaldla measured. That tells me he is not getting up to the pressures Ramshot or QuickLOAD get. Indeed, QuickLOAD shows a 20 grain charge would only be getting to about 17,000 psi if it produces the velocity Totaldla measured. This is clearly an ignition issue.

So, why did a low pressure load pierce a primer? When a gun is fired, the primer gas cannot instantly squeeze out through the flash hole, so the primer, acting like a little piston, pushes itself back out of the primer pocket. Chamber pressure later reseats it by backing the case up over it. In this case it looks like it flowed over that fat firing pin creating the inverted conical profile whose base happened to correspond to that chamfer in the firing pin bushing which offered not support to the edge of the primer. My speculation is that simply created too sharp a bend in the primer cup, encouraging it to crack.

I think I would not choose to use Enforcer with that bullet weight with lubricated lead bullets as they are unseated too easily and therefore offer less start pressure than jacketed bullets. I would also not use thin primer cups in a gun with that primer-diameter firing pin bushing chamfer.

[FrankenMauser]

It looks more like gas cutting from a cracked cup, than a typical rupture.

I think Unclenick's low pressure theory is closer to the truth, than any high pressure suggestions.

[totaldla]

Originally Posted by unclenick

This is not at all a high pressure load. Both the Ramshot data and QuickLOAD put it about 26 Kpsi when all the data is properly tweaked for matching barrel length and velocity. Enforcer is actually a slow powder for the application, and burns very inefficiently in it. That is part of the problem, since spherical propellants often have ignition issues in low pressure loads. The WFN bullet form is stubby, so there is about 25% empty space in the case, which exacerbates slow ignition.

The outer edges of the primer are not mushroomed, but they have sharp edges at the corners where the piercing is located. They correspond to the chamfer in the firing pin bushing, which could be expected to cause primer cratering in a high pressure load. Further, I notice the whole primer looks somewhat concave or inverted cone shaped around the pin indentation, another low pressure sign.

Further confirmation of the low pressure problem comes from the fact the velocity prediction from QuickLOAD matches the published pressure and velocity data for a 8.275" barrel, but shows 200 fps greater velocity with a 4" barrel achieving the same peak pressure with 20 grains of Enforcer than Totaldla measured. That tells me he is not getting up to the pressures Ramshot or QuickLOAD get. Indeed, QuickLOAD shows a 20 grain charge would only be getting to about 17,000 psi if it produces the velocity Totaldla measured. This is clearly an ignition issue.

So, why did a low pressure load pierce a primer? When a gun is fired, the primer gas cannot instantly squeeze out through the flash hole, so the primer, acting like a little piston, pushes itself back out of the primer pocket. Chamber pressure later reseats it by backing the case up over it. In this case it looks like it flowed over that fat firing pin creating the inverted conical profile whose base happened to correspond to that chamfer in the firing pin bushing which offered not support to the edge of the primer. My speculation is that simply created too sharp a bend in the primer cup, encouraging it to crack.

I think I would not choose to use Enforcer with that bullet weight with lubricated lead bullets as they are unseated too easily and therefore offer less start pressure than jacketed bullets. I would also not use thin primer cups in a gun with that primer-diameter firing pin bushing chamfer.

Thank you for the work. It is really helping me to understand some of the potential issues involved. Again, thanks.