HK417 Firing Pin Striker Head Diameter Mystery
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Thread: HK417 Firing Pin Striker Head Diameter Mystery

  1. #1
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    Default HK417 Firing Pin Striker Head Diameter Mystery

    I purchased two Brownells HK417 parts kits. One kit was missing the firing pin so Brownells sent me a firing pin. The kits don’t come with bolt heads, so I ordered a couple from HK USA, but they said they’re back-ordered and I’d be looking at post-January before seeing them, so I decided to order a Brownells HK417 bolt head so that I could build at least one now. I’m in the process of building an upper and noticed that one of the firing pins wouldn’t fit through the Brownells bolt head, but one did. I measured the two firing pins and one has a 2.0mm diameter striker head and the other has a 1.5mm striker head. The Brownells bolt head firing pin opening is 1.65mm/.065”. On the Brownells site for their HK417 Bolt Head, a purchaser said that their firing pin, from a Brownells HK417 Parts Kit, wouldn’t fit through the Brownells bolt head and therefore had to widen the firing pin hole to get it to work.


    Questions:

    • · Are there two different firing pins for the HK417 that have striker head diameters of 1.5mm and 2.0mm?
    • · What is the diameter of the striker pin hole for an “HK” 417 bolt head?
    • Is the diameter of the striker pin hole for an HK417 bolt head the same as the diameter of the striker pin hole for a MR762 bolt head? Like the HK416/MR556 bolt heads, I was assuming they’re the same.


    It seems odd that there’s two different firing pin types and one seems beefier than the other. May it be because the Brownells HK417 Parts Kits are sourced from HK417 select fire guns and the Brownells bolt heads, and the replacement firing pin they sent me, are designed/sourced from commercial MR762s?



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    I am curiouse about this too...
    I bought two of the 417 Brownells kits and one kit had a firing pin with a larger diameter "striker" like you describe - I did not measure it though, but it was visibly bigger then the one in the other kit, and too would not fit through the hole of the Brownells bolt). I ended up just buying firing pin from HKPARTS.net, and a spare just in case (they fit just fine). I was also missing a flash hider from one kit, and the others flash hider was from and HK416, I was missing the goofy "extension" pin for the rear takedown detent/spring assembly, a couple detents between the two kits. I had already returned one of the HK417 kit because of missing parts, and just assumed that, that is just the way it is with them. But, between the two kits got one up, and going (minus a semi-auto Safety/selector), witch an MR762 Selector continues to elude me :(, and have other small parts on the way, so hopefully I have them both soon.

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    This is weird as to the best of my knowledge the 417 and 762/308 share the same bolt...
    "Just because you're paranoid doesn’t mean they're not after you!"

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    I experienced this same problem. I was surprised because I also thought there was only one type of firing pin / bolt head arrangement, but I guess HK had a reason to change the specs for a particular customer or need. I have a full BC date code HK417 BCG purchased from Gatewood Supply and the bolt head accepts the smaller (1.5mm) firing pin tip only.

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    Well it’s nice to know that I’m not entirely crazy! The date codes for the kits that I received are BB and BE and the BE came with a firing pin, but regretfully, I don’t know what the size was (1.5mm or 2.0mm) because I didn’t think there was a need to measure and by the time I started assembling, I had mixed up the pins. Eventually, I’ll get an HK bolt head and I’ll wait to see if it’s a bolt that accommodates a 1.5 or 2.0 before buying any more firing pins. Assuming there are bolt heads out there that accommodate the larger pin, I wonder if it’d be detrimental to the action if a smaller diameter firing pin was accidentally used…

    If there was a competition to see whose Brownells 417 kit was missing the most parts, I think I’d win by a big margin. I first bought just one kit and it was complete and in pretty good shape; I was impressed enough to order a second kit. I got the shipping message that “your package has been delivered” and arrived home to see a 13”x10”x6” box sitting on my porch. I thought that was odd as the first kit came in a 53”x14”x4” box. I opened the box and it contained a foam wrapped 417 handguard…nothing else. And, to make it even worse, they had placed a Brownells parts label on the wrapped handguard that said “HK 417 Parts Kit” / “100-026-984”. You’d have to get an empty box to beat that one!

    As of this AM, it looks like the HK417 Parts Kits are sold out…
    Last edited by Chesapeak610; 10-13-2019 at 04:32 PM.

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    @UMP45 ENTRY and @Chesapeak610 , I checked mine. All of my BCG items were purchased as MR762, none as 417. I have 2 complete HK OEM BCGs (1w/original 762 rifle and one as a spare straight from HK 3 years ago) and a Brownells bolt with HK BC items purchased as spares to make a complete BCG.

    All of my firing pins look the same, purchased 4 years apart from oldest to newest (purchase time not known manufacture date). I have to recheck the date codes on my HK OEM bolts because I want to say they are BD but that is earlier than I would expect for a rifle purchased new in 2015-16.
    Last edited by RegularGuy461969; 10-14-2019 at 01:04 AM.

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    I just checked mine. I have a BA dated upper. The firing pin that came with it seems to work fine in the Brownells bolt.

    I ordered a HK bolt back in February and am still waiting. Original delivery date was supposed to be June.

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    The difference:


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    HK417 Firing Pin Striker Head Diameter Mystery-firing-pin-strikers.jpgClick image for larger version. 

Name:	Firing Pin Strikers.jpg 
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    Here's my firing pins. I put a 416 pin in for comparison. Well, I think we’ve concluded that there are two 417 firing pin types (2.0mm and 1.5mm) and that the 1.5mm seems to be the more typical of the two types within this small sample size. Also, the 2.0mm types that we’ve identified came from Brownells HK417 Parts Kits and not from other sources (popular HK parts suppliers). Not that it matters much in the long run, but it’s a curiosity; I’ll do a little research to see why HK has two types…unless someone beats me to the solution.
    @willgaga , I too have a couple of bolts on order from HK, I spoke to a rep a week or so ago and he told me that their gun orders were taking priority for parts and that I’d be looking at post-January before seeing anything. When I made my order back in May, they said August/October time frame…seems like they’re sliding the date…
    Attached Thumbnails Attached Thumbnails HK417 Firing Pin Striker Head Diameter Mystery-firing-pins.jpg  

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