Does using 180-gr. bullets in .40 S&W’s really increase the likelihood of K-booms, as compared to lighter bullets in the same caliber?

Heavy bullets pushed hard in reloaded .40 cases can increase the chance of a case failure. Some refer to case failures in Glocks as KB's. Glocks can fire slightly out of battery which increases the chance of a case failure in an already weak .40 case. If you are going to reload for a Glock do not use lead bullets and do not push the pressure envelope. Also watch your cases very closely no matter what firearm they are being used in.

I have seen case failures in .40 caliber HK USPs, Glocks and 1911s. The .40 is a high pressure cartridge that should only be pushed hard with new brass.

Not if they have a proper powder load and no bullet setback. If you rechamber the same round over and over and the bullet starts to set back into the case, you may have a problem.

The 180gr panic originated because with a 180gr bullet there is not much room to spare in a .40S&W case. If the powder measure is heavy or the bullet is set too far in, pressures rise dramamtically.

I have shot several cases of 180gr ammo through a SIG 229 with no problems.

I agree with AR10. Bullet set back with reloads in the .40 is a problem I have had to deal with myself. I changed to Redding titanium dies and added a separate crimp die to cure the problem I was having. High pressure reload + bullet set back + unsupported chamber can = Kaboom. I have had no problems with 180 grain bullets as far as pressures go as of yet.

When I bought my first .40 in 1994, 180gr. loads where the most popular. That's all I used for years. Of course, it was an S&W 4006, not a Glock.

From what I've learned at TF, the SW 4006 and BHP were specifically designed to handle the higher pressure of the .40.  Not enough case support and firing out of batter are, from what I understand, the reasons Glock's had so many KB's.

I read a letter to the editor in a hand gun magazine about a subscriber having a KB in a glock shooting reloads. The writer said that he had learned later that shooting highpressure reloads in an unsupported chamber such as the glock pistol can cause problems with case failures in that same pistol.
My take on this is that Glock shooters need to be cautious(as everyone should)and not shoot reloads that other people have made. That includes all bullet weights and just not the 180 grainers. I shoot my own rounds that I have made up and no one elses. If you are shooting standard factory ammo you should have no worries.

Back when I used to have time to reload, I loaded for my .40 cal Glock's and never experienced any troubles with the 180s. I will admit that I pushed the envelope for hot loads at the time, and luckily never had any KB problems. I would either stick with factory ammo, or keep your reloads on the conservative side.

As far as Glock .40 pistols go, there are several reasons why you can get KB's:

1. Higher pressures the .40 S&W can generate
2. Unsupported chambers
3. The ability of the Glock to fire out of battery

If either of those factors were removed the instances of KB's would drop dramatically. That's why I prefer my Glocks in 9mm flavor, you don't hear of them KB'ing very much. While reloads likely are more common to cause KB's, they can occur with factory ammo as well, which has been documented. But a overcharged reload or factory load would undoubtedly increase the risk of a KB in a Glock or any pistol for that matter. Fortunately, if a KB occurs in a Glock, it's usually not too severe from what I have seen and heard, at least as far as severe injury to the shooter. But I wouldn't want it to happen in the middle of a shootout.

-CH

Right Troy, completely forgot to mention bullet setback. That's a biggie that can cause you to have a bad day no matter what pistol you are using. And with a .40, it's that much more critical.

-CH