The following information applies to both the HK51IMProved and the HK53IMProved in general except where noted.
RDTS HK51/53 IMProved Solves the maybe
BARREL & RECEIVER JIG
The weapons cocking lever housing tube is then shortened as is the cocking lever support. We join the cocking tube which is ribbed all the way up, as per the factory HK53 to the front forearm band.
We have seen some HK53 conversions that claim to be faithful to the factory with a taper into the front band. Again the factory outside appearance is a cocking tube ribbed all the way to the band that tucks into the front site. The cocking handle support is done in such a way as to not hang loose in the ejection port when the cocking lever is rearward and engaged in the slot catch ready to strip a fresh round out of the mag. A precision mill cuts a new cocking lever slot and catch in the cocking lever housing to facilitate the new configuration. RDTS positions the cocking notch just ahead of the top tube ribs giving a nice clean appearance.
The former cocking handle notch position is welded over and machined as to no longer be visible.
COCKING HANDLE OVER FRONT SIGHT LIKE THE FIRE BREATHING 51 BELT FEED
The cocking lever now lies on a stop over part of the front sight, like the HK51 Belted. This enables the 51/53-IMP in conjunction with other modifications to have a very strong and solid chambering stroke and recoil spring pressure.
THE WAY IT SHOULD BE DONE, THE WAY YOURS IS DONE
NO BOLT CARRIER MODIFICATIONS FOR THE HK53-IMP
The bolt carrier in our improved HK53-IMP is
not cut down in any way! This preserves the weight and balance
needed for reliable operation. Another benefit is the recoil
spring assembly is only shortened less than 1.5” and very few
coils of spring are removed making a very robust positive
functioning weapon. And if you have seen the way some 53
carriers have been cut up you could appreciate the uncut
carrier even more! The cocking lever support tube (the cocking
lever is attached to the tube that pushes the bolt back) has
very little removed from its length as opposed to having to
lengthen it. Another big benefit is you won’t have the failure
to chamber the first round that happens occasionally on
factory HK53 when using accidentally overstuffed 40 round mags. We've been told this never happens but we’ve documented
this on a few factory dealer sample guns we’ve had in the shop
DON’T REMOVE MORE THAN YOU HAVE
1. To start with we only remove aprox. 1.5” of length from the top carrier tube. The front top portion of a standard carrier, where the recoil spring passes thru, is a slightly larger diameter, this acts as a guide in the weapons receiver and lets dirt and debris fail behind it onto the smaller diameter of the carrier top guide tube. Our HK51-IMP Bolt Carrier is cut to length on a lathe and the larger diameter section rejoined to the carrier top tube. This is critical to reliable operation in that the larger diameter section has the proper bevel and hardness to let the recoil spring and guide go thru without binding and also prevents premature wear on your receiver that would be caused by a carrier that was simply cut and left with the smaller diameter to rattle around during operation!
2. The recoil spring guide bushing inside the Bolt Carrier is repositioned to optimize the recoil spring length which results in part to the very strong chambering stroke of the 51-IMP. If this was not done the recoil spring would not be able to attain the length needed for reliable operation with the original HK spring, which would result in a heavier spring being used that would also bring the rate of fire up beyond the optimum of 500-600 rpm.
MORE RDTS EXCLUSIVE
Listen up, what if you have several HK 308 caliber weapons and want to be able to use your Retractable (A3), Solid (A2) or maybe your 21E stock on your HK91/G-3 AND the HK51-IMP. With the other 51’s this is not possible due to the standard recoil spring and rod being permanently attached anyway, then cut back for use in the shorter weapon it would not then be usable in the full size gun. RDTS has solved this problem, when we build your HK51-IMP we reconfigure your recoil spring assembly to a removable assembly similar to the HK93/M33 or HK94/MP5. For a small charge per additional stock we can modify your other stocks and recoil springs in this manner. So if you have one recoil spring set up for the 51-IMP and another full sized you simply change spring assemblies to whatever stock suits you!
Our own RDTS factory markings have since 1991 been positioned at the rear of the receiver by the stock pin holes and are concealed by the stock.
Copyright © 2003
RDTS MANUFACTURING INC.