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how to tell if I have an 'action 3' bolt head

3114 Views 5 Replies 4 Participants Last post by  fullmann
any easy way to tell what kind of bolt head design I have in my 9mm clone?

the gun in question is a 7-ish year old bobcat.

I pulled the bolt carrier out the other day and the rollers came shooting out at me. upon further inspection, the retaining spring or plate was missing, no parts were evident, and for the life of me, I cant remember if it was a spring or plate.

as near as I can tell, the spring is the latest high speed version, but the plate is still available. HK parts has an action 3 spring, as well as a retrofit spring for all first gen bolt heads.

any help would be greatly appreciated.
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Link to one of many previous discussion: http://www.hkpro.com/forum/hk-nfa-talk/116914-what-do-i-have-action-3-f-modified-bolt-head.html

The Action 3 will have a cut out or depression in the face, the older style is flat (see photos in above thread).
The slot in the top of the bolt head (above the rollers) is narrower for the spring and the old style plate will not fit (but the newest F plate may, per Shattered ... hum wonder if have a F bolt head there?) While many of the guys have used the spring retainer instead of the plate, have seen where the spring shifted, wore through, fractured and damaged the inside of the bolt head ... in less than a case of ammo. So we tend to use what ever retainer the bolt was designed for (when the guys are shooting subgun matches get to see a lot of ammo go down range and lots of failures of firearms ;-)

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Link to one of many previous discussion: http://www.hkpro.com/forum/hk-nfa-talk/116914-what-do-i-have-action-3-f-modified-bolt-head.html

The Action 3 will have a cut out or depression in the face, the older style is flat (see photos in above thread).
The slot in the top of the bolt head (above the rollers) is narrower for the spring and the old style plate will not fit (but the newest F plate may, per Shattered ... hum wonder if have a F bolt head there?) While many of the guys have used the spring retainer instead of the plate, have seen where the spring shifted, wore through, fractured and damaged the inside of the bolt head ... in less than a case of ammo. So we tend to use what ever retainer the bolt was designed for (when the guys are shooting subgun matches get to see a lot of ammo go down range and lots of failures of firearms ;-)

This is not exactly correct.
The wider plate-style roller holder was designed for and first used in the "F" (French) model MP5 bolt head. It WAS NOT used in the original "Action 3" bolt head which came years before the F model. Both have the Action 3 bolt face scallops but only the F version has the larger (wider) plate roller holder. The Dynamit Nobel/Geco Action 3 ammo with unique ogive favored by German police required some help in feeding thus the face scallops. These special cuts were retained in the F model bolt head as they do not adversely effect feeding of other types of 9mm ammo and the stronger roller plate, added to deal with high pressure ammo that the French police wanted to shoot in their MP5's, do seem to hold up better, sometimes. The F model plates still break depending on the ammo used, firing rate and other factors. This still remains like the extractor spring design the weakest point on the MP5 and other HK roller-locked weapons.
Wise owners have spares.
G3Kurz
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This is not exactly correct.
The wider plate-style roller holder was designed for and first used in the "F" (French) model MP5 bolt head. It WAS NOT used in the original "Action 3" bolt head which came years before the F model. Both have the Action 3 bolt face scallops but only the F version has the larger (wider) plate roller holder. The Dynamit Nobel/Geco Action 3 ammo with unique ogive favored by German police required some help in feeding thus the face scallops. These special cuts were retained in the F model bolt head as they do not adversely effect feeding of other types of 9mm ammo and the stronger roller plate, added to deal with high pressure ammo that the French police wanted to shoot in their MP5's, do seem to hold up better, sometimes. The F model plates still break depending on the ammo used, firing rate and other factors. This still remains like the extractor spring design the weakest point on the MP5 and other HK roller-locked weapons.
Wise owners have spares.
G3Kurz
The "wide" plate slot exists on the old style non scalped bolt faces. Thus had assumed (in correctly it appears) that there was a progression of wide to narrow slot. However, if I have it correct this time, the narrow slotted scalped bolt face bolt head is the Action 3 and the wide slotted scalped bolt fact bolt head it a F type?

In which case where does the narrow slotted F type come in? See Link: http://www.hkparts.net/shop/pc/viewPrd.asp?idproduct=69&idcategory=90
Post pics of the bolt head.
so I finally found the parts in question, I guess the one pic should tell it. not action 3 or F, no scallops on the face.

so I guess I need the plate...http://www.hkparts.net/shop/pc/HK-German-Roller-Retainer-Plate-For-Rollers-144p65.htm, or the 'drop in upgrade' from hk parts....Roller Retainer Spring - HKPARTS.NET

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