Excessive pressure shown in primers ?

[WDS]

This is my first try at lead bullets in .40 S & W.

Bullets are LEE 401-175 TC water dropped wheel weights + 2 % tin and sized to .401" or .400" in diameter. Powder is Alliant Power Pistol, 5.7 grains. Primer is lead free from PMC.

The top row of the picture were fired in a Glock, bottom row in a Beretta. I have changed primer brands, changed the powder charge up and down, changed brand of cases and changed the bullet diameter. All loads have an OAL of 1.135". The appearance of fired primers appears to be consistent in all of my tests.

The primers in the bottom row appear to me to have a circular raised area around the firing pin detent. I am concerned that this may be an indication of excessive chamber pressure. I would appreciate any opinions as to what's going on here.

[gray wolf]

They look normal to me, the Glock primers have the typical hour glass mark from the
breach face. There seems to be a little drag from the firing pin, the hit is elongated a little, could indicate a timing issue. Slide movement while pin is still protruded.
Could be normal for the Glock. I see it all the time with factory ammo.
The primers from the Beretta also look quite normal. It doesn't take much to impart breach face marks on the face of the primers. The little half moon is also quite common.
I think high pressure would show as a flattened primer with the cup rolled into the corners of the primer pocket.
I don't have my notes but I think your O A L is long ( long loading ) not a problem unless it creates one with function and should ease pressure unless the bullet is jamming into the barrel lead. I don't have the max load for your set up but if you are below max You are probably OK.
Is that brass very old ? are you up to speed about the Glock bulge on the brass ?
How do you say .400 .401 ? don't you know ? Most 40's shoot .401
Any leading ? OK that's it for me, lets see what the other boys have to say.
Flat primers can indicate high pressure but it is not always an indicator.
There are times a load can be dangerous and the primers are not flat. (read as not always)

[NSP64]

I was wondering if you slugged the barrel with a pure lead slug?
If so, what did it measure?
Are you able to push a boolit back in the case with finger pressure?

[ColColt]

Primers are not the best source of pressure checks unless they're cratered or perforated and maybe black soot around them.-then you can safely say you're into dangerous territory or getting awfully close. I always try to stay less than max in the reloading manuals as you don't gain anything by going over it. Most accuracy, including rifles or pistols, are at slightly under max.

I don' t experiment and see if a given firearm can stand more pressure/velocity. Pressure testing equipment is most expensive and out of the reach of most of us. I'd stay within the manual's recommendations for most loads or go to one of the company's data base, like Hodgdon or Alliant. Those primers look normal to me. A revolver will tell you when pressure is high as the cases will be more difficult to extract.

[WDS]

Thank you for your comments ! The Glock has an aftermarket barrel with conventional rifling and a very tight chamber. It slugs at .400 for groove diameter and fully supports the case. Bullets were seated to maximum OAL according to the Lyman 49th edition manual. There appears to be no issues with feeding or extraction at that length. The brass was fired two times at the time of the photo. With 40 caliber, I'm trying to be very careful since it is a high pressure cartridge. I have shot bullets at .400 and at .401 diameter. Both diameters will chamber in the Beretta but with the after market barrel in the Glock, only the .400 diameter will chamber. Both bullet diameters seat firmly in the cases without any unwanted movement of the bullets due to recoil. There has been no leading whatsoever in the barrels.

[ku4hx]

I don't think your primers are showing an overpressure situation, but then I'm not shooting your gun. Alliant lists a max load of Power Pistol for a 180 grain jacketed bullet as 7.2 grains. The "traditional" starting load of 90% would therefore be 6.5 grains and you're well below that at 5.7 grains. The times I've been convinced I did have too high pressure the primers were completely flattened. But then some primer cups are softer than others.

With your exact boolit, I load mine to a COAL of 1.100" - 1.105". I've just never been able to keep dimensions exact so I shoot for an acceptable range. Functioning in all guns is flawless; with both OEM and Lone Wolf barrels in the Glocks. Incidentally, my Remington Golden Saber factory rounds for 165 and 180 grain mic at 1.130" and 1.125" respectively. For the one box of each I have, the 165s are consistently longer than the 180s. Go figure.

The cases I use exclusively for 40 S&W are true once fired Federal nickle plated gotten from my nuclear plant's range; alloy has 2% Tin like yours ... I air drop only. I've never seen a Glock bulge in any of them from either my model 27, 23 or 22. The same goes for my Smith 411. I split the difference and load 6.8 grains Power Pistol with the Lee 175 TC sized to .401"; I feel my pressures are fine. My PACT2 shows MV at 10' to average right at 950 fps from my G22. I haven't clocked the other guns.

[WDS]

Hi ku4hx:
The largest powder charge that I have tried was 6.1 grains of Powder Pistol which yielded average velocities of 1016 fps. and cratered primers. The 5.7 grain charge gave velocities of 916 fps from my Glock model 23 and a Beretta model 96 having two different barrel lengths between them. I have checked my powder electronic powder scale against a beam type scale to confirm its accuracy. I think that I will have to break down and buy a box of factory loads to check the chronometer although I have not found its data to be suspect.