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What are the differences between a F bolt group versus the standard bolt group? I know the bolt carriers have a different design.....how about the timing piece etc.? Thanks.
 

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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.
 

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Discussion Starter #3
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.
Thanks. What, specifically, is the difference between the F group and the standard group?
 

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Improved roller retainer and new/diffferent bolt head to accept the improved roller retainer (the new head may have the front scaples as in the Action 3).

Improved firing pin spring - check out http://www.hkpro.com/mp5.htm for photos.

There was also a change to the bolt carry (necked down tube in front), that is around this time frame. Plus if memory is correct, the F series has a different recoil spring.
 

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Converting old to new?

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.
 

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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.
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.

If you shoot +P+, I think you should replace the recoil spring as well.
 
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