Gun Fun TV

HKpro.com

Many parts of the HK53 are interchangeable with the MP5, they are so similar in size.  The example above shows us the newer style  concave buttplate that until recently was only reserved for the MP5 series.  It is now available for the 33 and 53 series.  The forks are slightly longer on this model than for the MP5 series.  The four prong flash hider seen here is now standard.  It does much more to suppress the flash from this short barreled weapon than did the more standard flash hider seen on the 33 and G3.

There is also a frangible ammunition adapter offered as an option that provides the necessary back pressure to cycle the HK53 reliably with very light .223 caliber frangible ammunition that is now available for entry situations where deep penetration is more undesirable.  This may prove somewhat unnecessary, since the national trend of adopting .223 caliber firearms for tactical entry is proving that there is generally less ancillary penetration of  conventional .223 caliber projectiles than even pistol caliber submachine guns.

Entire article here