...the HK 416 is very similar to the the other DI converted piston guns...such as the LWRC and LMT...the piston rod or gas piston / tappet combination...drives the weapon by striking a bumper located on top of the carrier...this force is considerably "off axis" relative to the reciever's raceway's axis...not good engineering when the carrier is not captured by a railed raceway...as is the SIG 55x for example...the multi lugged bolt uses the AR design...including the "in face" ejector...HK even coppied the "little black extractor insert" found in the AR's extractor cup...
...the HK 416 uses a slightly modified AR carrier with a bumper...
...notice the cam pin...no real change there...
...the modified AR type bolt...at least they got rid of the gas rings...
...the recoil spring and buttstock...
...the one plus is that the HK does use a more robust piston drive than "some" of the others...but the upper reciever is still constructed from aluminum...not steel...precluding the use of a captured steel carrier gliding on hardened steel rails...
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