I'm new to reloading and just did my first batch of .40 a month ago. I bought an upper, quick change kit, and dies to use on a friend's Dillon 550B lower. On that first batch of 1k, I let my friend do all the setup and I just lent the elbow grease.

155gr Berry's flat nose
CCI 500 small primers
9gr Power Pistol powder
collected range brass

Needless to say, those rounds were more than a little hot and flashy. In fact, the first two rounds gave me a decent scare thinking I had overcharged them. But, the spent casing showed no signs of cracking, overpressure, etc. Although, at 2 different ranges, I've had the range officer come over and check to see what I was shooting. At the indoor one, I'm guessing it must have been abusive to everyone around me. Shooting outdoor steel plates last weekend, the RO actually limited me to the 50 yd plates. Anyway, those are used up except for a few to chrono.

I was doing some research on the next batch of .40 reloads I want to do and came across this webpage - Why the 180gr Bullet is a Bad Choice for .40 S&W. The author makes the case that 180gr loads can easily exceed maximum pressure tolerances of brass with just the slightest variance in OAL(which happens). The danger can become critical with used brass from guns that don't have fully supported chambers, like Glock.

The official industry pressure specification for .40S&W is 35,000 pounds per square inch (for those who don't already know)

Here is a chart he provides on OAL and pressure:



I have no idea if this is factually correct, an old issue no longer relevant, or complete BS. So, I thought I'd run this by some experienced reloaders before attempting.

I suppose that's the reason people chrono test rounds and work the way up in small increments. Then, allow enough headroom for the unavoidable small variance in OAL?