Hole in the primer

[Julien Boit]

Hi all,

I'm coming to all of you guys to solve a problem with my dad's pistol.

Most of his primers came out with a hole, and the firing pin spring gets all the residue.

The gun is a SV frame/slide with a Lothar Walther barrel in 40sw.

The headspace is right. First, I thought a bout the FP get stuck through its hole, so I checked it.

I did a little bit of filing to let it drop freely, I also rounded up its end.

Put a new FP spring.

But it still continue, about 30 to 40 % of the primers got a hole, some shows signs of excessive pressure.

The load is exactly the same I use in my pistol and if I shoot his ammo, the phenomen doesn't appear

The only thing I think about now is a poor barrel fitting.

Any ideas ?

[ErikW]

A pierced primer (darkened hole) is a very bad sign of high pressure.

I would say chronograph the loads but they are unsafe to shoot. Back off the powder charge and chronograph. It could be your father's gun has a very "fast" barrel that generates more pressure with a given load.

[Skywalker]

Julien,

as EW already pointed out, if the primer is flattened, pierced (hole in it) and cratered (hole edges protruding outwards) it's a very bad sign of high pressures.

Now to the (possible) causes.

1. I guess you have already checked the freebore of your dad's barrel. Maybe, if this is a custom barrel, it has some sort of zero freebore with the OAL and bullet type of your reload. Check it by taking off the barrel, and dropping a round in it to see if it chambers completely without drag (rifling engaging bullet when bullet base is flush with barrel end).

2. Is your dad's barrel sized the same as yours? Could it be you have a barrel sized for .401" bullets, and your dad's is sized for .400"? This might raise pressures, even more if you are using a fast powder.

Does it show the same tendency with factory ammo?

What about different reloads/bullets (i.e. lead, plated, jacketed)?

Mind to share your load, to get feedback from other reloaders?

Take care...

[Julien Boit]

You're right guys, I'll chrono them.

Sky:

The chambering is fine, the cartridge drops freely inside the chamber, but I must confess that I didn't take the measure of the bore

I can share my reloads but I'm not sure (pretty sure in fact ) that you wouldn't find the same components, not for case and primers, maybe powders too but for bullets.

They are copper plated 167 grs made locally, and some are rather on the smaller side (.399 instead of .400)

The thing that is funny is that it already did it with his previous pistol.

A BUL M5

[Skywalker]

Maybe it would help if you could post a couple of pics of the fired brass.

If the same load showed the same tendency in another gun, maybe it's your gun that has some special chambering, that with your load allows lower pressures than in other guns?

In any case, a chrono will help there.

[tightloop]

Don't know how many you have loaded, but I would not shoot any more of those.

[Guy Neill]

Is the hole in the primer a blanked hole the size of the firing pin tunnel (clean cookie cutter type) oe simply a leak of gas at the bottom of the firing pin indention?

The first can occur if the firing pin spring and firing pin are not offering enough support (weak and/or lightweight, but length of the firing pin has also come into play in the past). The second would more point to excessive pressure. In rifles, the first culprit is normally a weak striker spring when the priemr is blanked (cookie cutter effect). Too large a firing pin tunnel can also make a difference. More precisely, the fit of the firign pin in the tunnel.

You might try your firing pin and spring in his gun to see what sort of difference you see.

Guy

[Julien Boit]

Thanks for the advice Guy, I'll try it.

[John Thompson]

With the zillion catagories for threads here we still get one now and then that doesn't really fit in just any one of them. I almost moved this thread the re-loading forum