Short answer: "grain" is the weight of the bullet. A grain is a small unit of measure.Rich1028 said:whats the difference in 155 grain,165 grain,180 grain?
this is for my glock 23 40 s&w
the lower grain is lower in price.
In essence, given the same caliber, different grains matched with different loads create different pressures resulting in different flights.
For target/practice shooting at average distances (7-20 ft ish) it won't make a significant difference. For match shooting, serious competitors like to "mix their own recipes."
I'm not familiar with .40 cal but average factory grain for .45 is 230gr. 185gr .45 is very light IMO. I prefer the heavier bullet.