It's Not Really Science If You Change All The Conditions

I loaded up 100 rounds of low recoil 40S&W, using new Starline brass, Remington 1-1/2 primers and a slightly hotter 4.6g charge of Power Pistol and shot it from my Kahr CW40. So, other than keeping the Xtreme 180g RNFP projectile, I changed all the parameters of the test.

First, the Kahr is running it's stock spring, which is pretty stiff to judge by just a finger pull. I'm sure the smaller size of everything magnifies the apparent effort needed to cycle the slide, but the ammo never failed to extract or in any other way, fail to operate the pistol.

So long as it actually fired.

I had a few click-no-fire failures. Several, in fact. I recovered at least three manually ejected cartridges with seemingly light strikes. Upon closer examination, it appears that the primers are set deeper in the pockets than expected.

On the left is one of my previously loaded 180g rounds, with used brass and CCI primer. In the center is a light strike failure and on the right is an unfired "new" round. The really sharp observer will notice that the light strike is also a smidgen off center, but that is not generally a problem unless it's WAY off.

It may be tough to see in that picture, but the primers in both of the new rounds are noticeably set back.

Not sure if this is a better or worse illustration.

Since the previous load is in different brass and using a different primer, it's hard to compare them fairly, but the degree to which the new rounds are wrong is very clear.

Since I need to load about 200 rounds of ammo for a major match *tomorrow*, I need to resolve this tonight.

Most obviously, I will see what CCI or even Tula primers look like in the Starline brass. Before I load any, however, I will see if the Remington primers are smaller than the others and/or if the primer pockets in the Starline brass are different from the fired brass I have. The Remington primers gave me some fits anyway. They didnt want to feed reliably in the press. It seems to like CCI better. Actually, it seems to like Tula primers as well or maybe better. My hopes are very high that this will resolve the problem and I can use this load tomorrow without issue.

Using new brass was an unaccustomed joy. None of the usual QA gyrations that fired brass needs seemed to even apply. Never fired means never GlockBulged; loaded rounds dropped straight through the bulge buster without interference, so that fairly time consuming step could be eliminated. Thanks to a minor adjustment of the crimping die, they dropped into and out of the gauge block as well. I did not put a caliper on every round, but the 20 or so random rounds that I checked were all dead on 0.419" at the case mouth and OAL 1.115", +/- 0.001. That is a little short, so I will move that out to 1.120" or so. I have had some feeding problems in the Lone Wolf conversion barrel of the Glock and that will likely help.

In looking up some figures about primer pocket depth, I came across an article about the dangers of loading 40S&W with 180g bullets. The gist of the article was that since the 180g bullet is physically longer than any other weight bullet, but that we maintain the same OAL, the combination results in significantly reduce loaded case volume. This volume does indeed affect the burn rate and peak pressure of any powder in any round and the article included a scary chart showing that a variation of 0.140" in cartridge OAL and thus case volume, resulted in pressures soaring as high as 4 times the maximum SAAMI pressure for the cartridge.

The same sort of problem comes from too light of a crimp on an autoloading pistol cartridge and even more often, chambering the same cartridge over and over (like you might do if you unload and reload your carry ammo into a pistol you also compete with) can set the bullet back from being rammed into the feed ramp. At the very least, it can affect accuracy because the pressures vary from shot to shot and in the worst case, your pistol comes apart in your hand due to extremely high pressures, possibly taking your hand with it.

In my case, I think my handloading goal avoids this issue. I am not loading anywhere near full power, let alone max power. Just the opposite, in fact. I am developing the lowest power load that will meet minimum power factor for my competition and reliably operate the pistol.