What was commonly referred to as a “D” is generally the A1 and A2 variants, although A3’s were imported to the US and marked 416 D. The D stands for Defense and really has nothing to do with the features of the rifle.

The A3 includes a side-accessible adjustable gas block, captive cotter pin on bolt carrier, the ability to put the weapon on safe even with the hammer forward, a fire control bridge, a wider barrel index pin, and, when adopted by the Norwegians, a flip-up sight that attaches to the gas block.

 

Are MR556 uppers all considered A3 then?

 

I always wondered this…. Great info!!

 

One question, wasn't the original 416D A1 spec for the ability to safe the firearm with hammer forward? I onow my 2014/15 556's sure did have it. So would you consider those A3's... ?

Here’s a more comprehensive breakdown of HK416 through A3 variants so you can see the differences.

• HK416 - Lacks a firing pin safety or firing pin spring.

• HK416 A1 - Features the addition of a firing pin safety and firing pin spring.

• HK416 A2 - “Over the beach” capable, including the barrel (OTB).

• HK416 A3 - Includes a side-accessible adjustable gas block, captive cotter pin on bolt carrier, the ability to put the weapon on safe even with the hammer forward, fire control bridge, a wider barrel index pin, and, when adopted by the Norwegians, a flip-up sight that attaches to the gas block.

The “D” stands for “Defense” and was used on rifles imported to the US for iterations of the HK 416 through the A3 variant. With the A5 and 416C variants the “D” was no longer used on rifles imported to the US.

Would I consider those A3’s? I’d consider all US MR556’s to me an amalgamation of A3 and A1. A1 for the gas block and barrel, but A3 in the bolt carrier group and fire control components. Which is as clear as mud. The slightly wider barrel indexing pin is not something virtually anyone is going to notice or recognize, so I tend to lean towards an A3 without the adjustable gas block.

If only James, Larry, Tom and Gun Jesus (Ian) would hurry up on the third installment (rifles/MGs) of the new HK bibles...

I whole heartedly agree. There is a lot of confusion surrounding the HK416 models and variants. I posted a more comprehensive list that includes models and their differences all the way through the A8 Here if you’re interested

 

Here’s a more comprehensive breakdown of HK416 through A3 variants so you can see the differences.

• HK416 - Lacks a firing pin safety or firing pin spring.

• HK416 A1 - Features the addition of a firing pin safety and firing pin spring.

• HK416 A2 - “Over the beach” capable, including the barrel (OTB).

• HK416 A3 - Includes a side-accessible adjustable gas block, captive cotter pin on bolt carrier, the ability to put the weapon on safe even with the hammer forward, fire control bridge, a wider barrel index pin, and, when adopted by the Norwegians, a flip-up sight that attaches to the gas block.

The “D” stands for “Defense” and was used on rifles imported to the US for iterations of the HK 416 through the A3 variant. With the A5 and 416C variants the “D” was no longer used on rifles imported to the US.

Would I consider those A3’s? I’d consider all US MR556’s to me an amalgamation of A3 and A1. A1 for the gas block and barrel, but A3 in the bolt carrier group and fire control components. Which is as clear as mud. The slightly wider barrel indexing pin is not something virtually anyone is going to notice or recognize, so I tend to lean towards an A3 without the adjustable gas block.



I whole heartedly agree. There is a lot of confusion surrounding the HK416 models and variants. I posted a more comprehensive list that includes models and their differences all the way through the A8 Here if you’re interested

See pic regarding BCGs.

Notice:

1) "free" cotter pin on AG or I 416 bcg and captive retaining pin on MR223A3

2) barrel preventer tab on MR gcb

3) less mass on bottom rear of MR bcg.

all of this is done to prevent conversion of MRs to FA.

My question, when did they start using captive retainer pins on the MRs. I don't think I saw one until 2018 when our favorite HK armorer ordered me two spare bcg's. I think they came with retained pins. But none of the MR556's I've purchased (last one in 2017, was a COMP) had captive firing pin retaining pins (IIRC).

 

@asillasitgets can we add this to the 416/556 FAQ sticky?