+p loads out of a 4" barrel

[THT]

I'm considering 124gr Federal HST +p 9mm rounds for my G19 however I was curious if the 4" barrel will affect the performance of the round?

[DocGKR]

Almost all 9 mm and .40 S&W loads are designed around 4" barrels--going up or down a half-inch in barrel length (ie. 3.5-4.5" barrels) will have negligible effects on terminal performance.

[THT]

Almost all 9 mm and .40 S&W loads are designed around 4" barrels--going up or down a half-inch in barrel length (ie. 3.5-4.5" barrels) will have negligible effects on terminal performance.

Thanks. I had read somewhere that barrels shorter than 5" result in reduced performance because not all the powder has time to burn by the time the bullet has left the barrel.

[Marcus L.]

Thanks. I had read somewhere that barrels shorter than 5" result in reduced performance because not all the powder has time to burn by the time the bullet has left the barrel.

That would be the .45acp in which "most" ammunition is designed around the 1911 5" barrel length. The 9mm, .40S&W, and .357sig are designed around the 4" barrel. Most ammo companies will list their test barrel lengths which 99% of the time follows this criteria.