I've started loading for a Ruger .480 as of late and found that my load - somewhat under listed maximum, causes primers to "flatten". Not in the usual rifle sense in that the metal flows to cover the bevelled part of the pocket, but after decapping, they have a sort of "T" look to them, a small ring around the edge of the cup side. I backed off another grain and the ring is still their though not as pronouced. At this point, it is similar in appearance to the factory fired primers. (I am using Large Pistol primers as per the published data). Is it really too much pressure or is part of this the result of using regular Large Pistol primers? Hogdon recommended cutting the load when I quered them.

What say ye?

Thanks,
Telly

I gave up trying to find out this answer. All loads I tested, either max or reduced charges, produced the same results; flattened primers. Though, my fired primers have a grainy look to their faces.

Problem with this is I don't know what is max. Maybe when the brass extract with difficulty from the cylinder holes?

I do know that I am getting less velocity out of every load I have tried when comparing the velocities produced by listed data using the same gun and components.

So, I load to the point of comfort. The point of proper recoil management.

Have you tested factory loads? Do they have flattened primers? What is their velocity compared to your reloads? They may have used a longer barrel. Just 'cause it is in the book doesn't mean you load 'till you get that velocity.

I've found my 7 1/2" SRH to be spot on for velocities from most loading data, and about 70 fps slower than data for 9 1/2" barrels, which is to be expected. My gun is a tad slow with the lighter bullets, but I didn't get the gun for light bullets. 400 gr cast bullets are IMHO, the best bullet for the round, and easily driven 1200 fps. I can't think of any game animal I'd hunt with a revolver that wouldn't cleanly be taken with such a load.

I've only fired a cylinder full of factory hornady loads, and they were slightly sticky in extraction. In a few instances I've had sticky extraction while working up loads using the same brass, but all my working loads extract freely. Easy extraction, chrono readings and keeping with published data is the only way I trust to keep track of pressure.

Primer shape is at best a poor and misleading way to judge pressures. Primer shape can however be a means of determining mechanical problems with the gun, ie headspace and firing pin problems.

Pistol primer cups are soft, and really not designed for the high pressures that many of the newer handgun round develop. I've never pierced a primer, but yes, they do flatten right out, and will show an imprint of whatever the face of your frames surface is like around the firing pin hole.