Thanks. What, specifically, is the difference between the F group and the standard group?The "F" bolt group is the latest/newest bolt group from H&K for the MP5 series. They are made to handle the much hotter +P and +P+ 9mm ammo. They are standard in all modern MP5 now.
Yes, they are a drop-in replacement. With the F bolt, you get the copper colored extractor spring, and the upgraded roller retainer, and I think the stranded firing pin spring. The F carriers are tungsten filled, and they'll drop in fine as well.Can an early MP5 be updated to the F bolt? Do you just put in the entire bolt & carrier and check head spacing? Is their any great benefit if you shoot it a lot but not +P? I have been wondering about this. I am in the process of collecting a new spare bolt and carrier for each of my HK machine guns and thinking about getting a F for my MP5.