MP5/K Bolt F Differences?

Unless you plan on running +P or +P+ ammo a lot, the difference will be just bragging rights. There isn't much of a difference you'll notice when punchin' paper. But you WILL have a piece of gun from they who surrender first!

You can use a "K" carrier in a full sized 9mm, but cannot use a full sized carrier in a "K".

Thanks Shattered! Do you know what the specific differences are between the stock bolt head and the F style and also the slightly older "Action" bolt head?

Visually, the "F" bolt head is noticeably scooped out, and contoured for better feeding but I don't have the specifics at hand. Someone else (Retro or AD) posted pictures of the bolt heads side by side so you could see the differences. Now all we have to do is sit on our duffs and wait for them to see the thread.

Why they want to go to all this bother for some troopies that are going to run away at the first sound of gunfire is beyond me...

Somebody uses their Action 3 much more than their F bolthead.

Whats the typical lifespan of a bolt head? I know the extractor and extractor springs require frequent change outs, but how long/rounds will a bolt head last?

SudS said:

Somebody uses their Action 3 much more than their F bolthead.

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The ratio would be defined by infinity.

retrodog said:

The ratio would be defined by infinity.

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Any particular reason for that?

I am guessing he has not broke the Action 3 bolt head yet ... ;-)

mikecleonard said:

Any particular reason for that?

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Sure, infinity is the limit of 1/x as x approaches zero. And if that isn't wacky, as x approaches infinity, the limit is zero.

But more likely, the Action3 bolthead works fine. No need to change it, the F is a spare. I have an Action3 as a spare, but only use the standard bolt head. As long as my cranialrectumitis doesn't flare up and I remember to change out the 53 ejector for the 9mm one, the standard bolt head runs fine so my Action3 can stay nice and shiny.

mikecleonard said:

Any particular reason for that?

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Well maybe it would be more in the "undefined" category.

I recently got an "F" bolt head and "F" carrier. They are still NIB as I haven't installed or used them yet. The "Action 3" is working just fine and I wanted another HK set since they are now declaring all the new ones as Class III hardware.

Shattered Mind said:

You can use a "K" carrier in a full sized 9mm, but cannot use a full sized carrier in a "K".

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I would not think the shorter K carrier would work in a full size MP5.
When you charge the weapon wouldn't the K carrier move back a shorter distance?

wh said:

I would not think the shorter K carrier would work in a full size MP5.
When you charge the weapon wouldn't the K carrier move back a shorter distance?

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Just repeating what one of the experts here stated. I myself have NOT tried it as it has been awhile since I had a "K" model in inventory and we didn't think of such things back then... .

I have an HK K carrier that purchased from one of the guys in Norway a few years ago .... he got it in a MP5 over there and it was working ...

I know now that all of the carrier components will only be sold to LEO or the military. So if I want to stock up on back up parts, I guess the bolt would be the most important? I already have the new f/a carriers for both my mp5 and mpk, can carriers break or be worn out? I'm thinking these parts unlike a cracked bolt can be refinished or repaired if needed, right?

In addition, all though not ideal, a semi auto carrier could be welded if that was the only option, so again, it seems like the bolt head would be the most in demand when these items become hard to find.

My local range had a 94 as a rental. It went through well in excess of 100k rounds (probably 200k). They went through several extractors (usually I would loan them one), that was the number one thing that caused down time. Other things that wear and break in addition to the extractor and spring, is the roller plate, and as the various parts wear down, the rollers.

I have several Action 3 boltheads as spares. I originally bought one to use in my RDTS SD, but I sold that gun and kept the Action 3. Then along came the DOJ 94s and I used F bolt groups in two of them, so then I had two more, and another spare when I got a factory SD kit. If I'm out shooting and a part were to break in the bolthead, I just switch out the bolthead and worry about the little offending part later.

majorjake42 said:

I know now that all of the carrier components will only be sold to LEO or the military. So if I want to stock up on back up parts, I guess the bolt would be the most important? I already have the new f/a carriers for both my mp5 and mpk, can carriers break or be worn out? I'm thinking these parts unlike a cracked bolt can be refinished or repaired if needed, right?

In addition, all though not ideal, a semi auto carrier could be welded if that was the only option, so again, it seems like the bolt head would be the most in demand when these items become hard to find.

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You never really know when you're gonna want to get a new gun. And if it's a new clone, you just might want a set of HK bolt parts to put in it.

I have a second CA89 NIB. Well it's pretty much NIB as it's only been shot enough to make sure it works fine. Anyway, I just bought the parts because I wanted to have them just in case I wanted or needed to use them later.

But apparently, the clone bolt carriers are built pretty well too. The bolt head seems to be the part that affects feeding and ejections the most. Some of the Coharie bolt heads have been a little to big where the rim of the shell sits and makes it loose. I have four Coharie bolt heads and two of them are what I'd classify as too large. They work fine in SA but have problems in FA. The Rim Country bolt heads are also available and might be more consistant. Not sure.

In any case, the clone bolt heads run about $150 which isn't bad at all.

Bolt Heads and Carriers

Could someone please post pics of side by side bolts and carriers, semi and full. I have several spare parts and don't know what to look for. Thanks.