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GregLaROCHE
05-10-2018, 04:45 AM
I am new to cast boolits. Not to reloading, but to trying to find an exact proven load for a given round and boolit weight. To check if I overloaded I should look for cratered primers. What do they look like? Any pictures available?

And while I have you on the line, are there any pictures of barrel leading.

PS: Does anyone remember when Pres. Reagan called a guy in the hospital to wish him well and he said “Mr President, while I have you on the line, what about that tax return I have had coming for years” or something like that?

Retumbo
05-10-2018, 06:25 AM
Primer is not always a good indicator of over pressure.

These primers ate flattened, not by excessive pressure but excessive headspace.

220149

sparkyv
05-10-2018, 07:26 AM
Primer is not always a good indicator of over pressure.


Best to start with some known, acceptable pressure rounds, and compare your loads to those. Usually, factory ammo is a good reference to start with.

BK7saum
05-10-2018, 08:43 AM
Rifle or pistol? If you are looking at cratered primers in a rifle to check if overloaded, you are probably well beyond an acceptable pressure where accuracy is good.

In pistols, I have found looking at primers to be unacceptable regarding pressures.

Just use reliable data and work up your loads to get acceptable accuracy.

Ballistics in Scotland
05-10-2018, 09:32 AM
This is a very extreme example, not perpetrated by me, of a primer cratered in an attempt to develop an Improved version of the already huge .244 Holland and Holland Magnum. Note that the necessary pressure imprinted the ejector slot on the case head. I'm told it was done in a remotely fired pressure gun, but doing this in a conventionally fired rifle would be very, very dangerous, and in a remotely triggered one it could be very, very destructive. Much the same applies to a primer widened into the bevelled edge of the primer pocket, so as to be ever so slightly T-shaped in lengthwise section. Headspace is a major factor in producing this, though, and in producing cratering, not so much.

Even if the rifle stands the pressure, it is very close to blowing out a neat circular section of the primer. That is worse than an excessively long or pointed firing-pin puncturing a primer. A lot more gas escapes into the bolt body, perhaps back into your face if the design isn't good at deflecting it, and there is a chance of the missing bit of primer metal jamming the firing-pin on another shot.

Pressure isn't the only variable in determining whether a primer is cratered. A light firing-pin or hammer, or perhaps one with a tendency to bounce, can be a contributing factor I think it is fair to say its absence isn't proof of safety, but its presence is proof of unsafety. In the sort of rifle that commonly uses black powder, I would call even a sharp edge to the firing-pin indentation food for thought.

Ballistics in Scotland
05-10-2018, 09:50 AM
Rifle or pistol? If you are looking at cratered primers in a rifle to check if overloaded, you are probably well beyond an acceptable pressure where accuracy is good.

In pistols, I have found looking at primers to be unacceptable regarding pressures.

Just use reliable data and work up your loads to get acceptable accuracy.

I agree about pistols, and most pistol-cartridge rifles. Except in the comparative sense. When your load produces primer deformation comparable with the one produced by a load you know is acceptable, in the same firearm, you are on pretty safe ground.

Retumbo
05-10-2018, 12:32 PM
This is a very extreme example, not perpetrated by me, of a primer cratered in an attempt to develop an Improved version of the already huge .244 Holland and Holland Magnum. Note that the necessary pressure imprinted the ejector slot on the case head. I'm told it was done in a remotely fired pressure gun, but doing this in a conventionally fired rifle would be very, very dangerous, and in a remotely triggered one it could be very, very destructive. Much the same applies to a primer widened into the bevelled edge of the primer pocket, so as to be ever so slightly T-shaped in lengthwise section. Headspace is a major factor in producing this, though, and in producing cratering, not so much.

Even if the rifle stands the pressure, it is very close to blowing out a neat circular section of the primer. That is worse than an excessively long or pointed firing-pin puncturing a primer. A lot more gas escapes into the bolt body, perhaps back into your face if the design isn't good at deflecting it, and there is a chance of the missing bit of primer metal jamming the firing-pin on another shot.

Pressure isn't the only variable in determining whether a primer is cratered. A light firing-pin or hammer, or perhaps one with a tendency to bounce, can be a contributing factor I think it is fair to say its absence isn't proof of safety, but its presence is proof of unsafety. In the sort of rifle that commonly uses black powder, I would call even a sharp edge to the firing-pin indentation food for thought.

I have seen similar primers from bolts with oversized firing pin holes using federal ammo

GregLaROCHE
05-10-2018, 11:33 PM
Thanks for the photo. Now I understand why they call it a cratered primer. Mine are not like that at all. At the bottom of the impression on mine, it’s as if it is eroded and I can see pin holes through the metal of the primer. Very small holes. The ten shot all look the same. All primers came from the same CCI box.

I’ll see if I can get a picture to post. I’ve never taken a picture of something that small before.


This is a very extreme example, not perpetrated by me, of a primer cratered in an attempt to develop an Improved version of the already huge .244 Holland and Holland Magnum. Note that the necessary pressure imprinted the ejector slot on the case head. I'm told it was done in a remotely fired pressure gun, but doing this in a conventionally fired rifle would be very, very dangerous, and in a remotely triggered one it could be very, very destructive. Much the same applies to a primer widened into the bevelled edge of the primer pocket, so as to be ever so slightly T-shaped in lengthwise section. Headspace is a major factor in producing this, though, and in producing cratering, not so much.

Even if the rifle stands the pressure, it is very close to blowing out a neat circular section of the primer. That is worse than an excessively long or pointed firing-pin puncturing a primer. A lot more gas escapes into the bolt body, perhaps back into your face if the design isn't good at deflecting it, and there is a chance of the missing bit of primer metal jamming the firing-pin on another shot.

Pressure isn't the only variable in determining whether a primer is cratered. A light firing-pin or hammer, or perhaps one with a tendency to bounce, can be a contributing factor I think it is fair to say its absence isn't proof of safety, but its presence is proof of unsafety. In the sort of rifle that commonly uses black powder, I would call even a sharp edge to the firing-pin indentation food for thought.

Bazoo
05-11-2018, 12:09 AM
Primers with holes in them is the next step in pressure past cratering. Pierced primers is a sign of very excessive pressure, Unless of course... your firing pin is too pointy. In that case, it would most likely pierce any full power loads.

Mr_Sheesh
05-11-2018, 02:33 AM
Definitely, holes in the primers is NOT good. Change things till those go away, definitely, ASAP. Especially with CCI primers (they are thicker and harder than some brands by a little bit I think.)

Ballistics in Scotland
05-12-2018, 05:26 AM
Thanks for the photo. Now I understand why they call it a cratered primer. Mine are not like that at all. At the bottom of the impression on mine, it’s as if it is eroded and I can see pin holes through the metal of the primer. Very small holes. The ten shot all look the same. All primers came from the same CCI box.

I’ll see if I can get a picture to post. I’ve never taken a picture of something that small before.

I don't think that is due to excessive pressure at all. The usual way that goes wrong is by detaching the depression, altogether or in part, around the edge of the depression. What you have sounds like a firing-pin problem that can occur at about any pressure. It can be because the firing-pin is too sharply pointed, but also when the shape is fine but it is too long, and the primer metal is pinched between the pin and the anvil. It isn't particularly dangerous in most firearms, as the amount of gas liberated is very small. With black powder firearms the fouling can promote rusting in places you don't really want to wash out with water, and I would especially want to avoid it in guns like break-open rifles, rolling-blocks, the Stevens 44 etc., here the escape route for gases is uncomplicated.

I had it with a .38S&W Webley revolver, which was surely among the lowest-pressure of any bullet-firing firearms. I cured it by a very slight amount of oilstoning of the tip, but you should check it carefully before you do that.

Good measurements for the firing-pin tip are .075in. diameter and .065in. protrusion for large primers, and .062in. diameter and .05 protrusion for small. Specific diameter is less important than making the pin a close fit in its hole, but the protrusion is quite critical, since it should not exceed about .002in. over the stated dimensions, and it does not take a great deal more to cause trouble. Note that protrusion can grow under repeated pounding by dry-firing. It is also quite important that the pin, in a high-power rifle, should have a spherical or slightly pumpkin-shaped tip.

This is a rather puzzling picture I took with an old-fashioned film camera (though less than half as old as I am), and an adapter for a microscope. It shows the beginning of a crack around the firing-pin depression, and the odd thing is that the lip of the depression on the other side looks perfectly healthy. Cratering on the right may have been quite moderate, although some might have been flattened out. Unfortunately I don't know whether any special construction of that unplated primer was responsible for that, since it was just a .308 case I found somewhere. It might be that rust or damage had made the mouth of the firing-pin hole slightly bell-mouthed on one side only.

220288

GregLaROCHE
05-12-2018, 08:57 AM
Thanks for not forgetting this thread.

I have tried to upload a picture for two days, but keep getting error messages. My internet connection is by satellite and pretty slow. That’s probably the problem.

At first seeing the pictures of the cratered primers, I thought that’s not my problem. Them when I took them out into the sunligh to take the pictures, I started to think I did have an over pressure problem. Today I looked at some of my old brass and it’s not quite as bad but similar. Even factory loaded Winchester.

I was wondering if it could be a head space issue. The rifle is a CG 63. A rifle that was built for the Swedish marksmanship contests. It hasn’t been shot much and they are know for having very good tolerances. That’s why it’s hard for me to think it’s something with the gun. It must be something I’m doing wrong.

I’ve loaded ten more with a lot slower powder. I will try them tomorrow and post what happens.

Retumbo
05-12-2018, 09:13 AM
It could be. It could also be uour slow powder. If the case does not seal properly it can dislodge the primer when firs fired. Building gas the pushes the case and extended primer against the firing pin.

See gif below now imagine instead of the head seperating the whole case goes back against the firing pin.

https://lh4.googleusercontent.com/-A1DcsQZUWyU/TXXEPDO2WqI/AAAAAAAAAHI/VaSFJCyUXUE/s1600/2u5z31t%255B1%255D.gif

GregLaROCHE
05-12-2018, 09:25 AM
This is what I was thinking, but I wasn’t using a slow powder. I’m trying slower powder tomorrow. It even happened, to a lesser extent, with the factory loads. The primer indents just don’t look normal. They’re not smooth and cup shaped.


It could be. It could also be uour slow powder. If the case does not seal properly it can dislodge the primer when firs fired. Building gas the pushes the case and extended primer against the firing pin.

See gif below now imagine instead of the head seperating the whole case goes back against the firing pin.

https://lh4.googleusercontent.com/-A1DcsQZUWyU/TXXEPDO2WqI/AAAAAAAAAHI/VaSFJCyUXUE/s1600/2u5z31t%255B1%255D.gif

Ballistics in Scotland
05-12-2018, 03:49 PM
I think excessive headspace is likely to produce an unusually sharp edge around the perimeter of the primer, or extrude it slightly into the pocket's bevelled edge, especially if the bevel is exceptionally large. But I can't see how headspace would increase any tendency to crater the primer.

GregLaROCHE
05-13-2018, 09:52 PM
I shot again with slower and faster(factory) rounds and all look similar. I asked an experienced reloader and he said it wasn’t from over pressure. Maybe from the tip of the firering pin not being smooth, but not to worry about it.

I wish I could get the pictures uploaded, but I keep getting the error message. It’s three in the morning when my connection is the fastest, but still that error message.

Thanks for all the advice. If anything new arises I will post it.

sigep1764
05-13-2018, 10:59 PM
Lower the resolution on your pictures to around 20. It will look like a thumbnail pic, but the size is bigger in your posts.

GregLaROCHE
05-14-2018, 11:55 PM
Here are some pictures of the primers in doubt. There not as clear when pixel size reduced.

Bazoo
05-15-2018, 12:29 AM
They dont look over pressure to me.

Is the firing pin hole smooth on your bolt face?

GregLaROCHE
05-15-2018, 07:01 AM
You can’t really see it well in the pictures, but the ding in the primer is rough and pitted. Factory loads look pretty much the same. I am wondering if the end of the firing pin got roughed up some. Maybe I should try polishing it, but I am afraid I might change the length too much.

Bazoo
05-15-2018, 11:10 PM
Id spin it in a drill and touch some 1000 grit sandpaper to the nose. If you dont get wild with it you wont shorten it hardly any.

Mr_Sheesh
05-19-2018, 07:21 AM
If the end of the firing pin was corroded somehow, that could make it rough etc. perhaps?