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.
- · 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?