Use Belts or links! No problem.
Here's some stuff that will be on our HK21EUG info page. Most of you can do the mod, just think about it for a few minutes after checking it out, not that big a deal.
HK 21’s were designed for MG3 type belts and not M-60 disintegrating links, however both can be used. MG3 belts tend to be a pain if you want to pack it up before the belt is done. The belt sticks on everything trying to back it out. But we give you the option to use what’s convenient and the best for your shooting session.
The problem initially with links is the distance apart the rounds are. If you lay a loaded MG3 belt and an M-60 linked belt side by side you’ll notice the spacing is closer on the M-60 linked belt. Load your 21 that has an unmodified feed mech and chamber a round out of a M-60 linked belt, now as you manually pull back to eject the unfired round notice as the bolt head travels rearward over the round underneath in the feed mech. You will see that it’s getting deformed and smashed by the bolt head. This creates a lot of drag as the bolt is trying to eject the spent case in a firing situation. The reason for the drag is not the links thickness but rather because of the shorter spacing of the M-60 links. What has happened is the 2nd and 3rd round back in the belt is being pulled into the star wheel and can go no further. The reason it’s getting pulled into the wheel is the round that’s ready to chamber is sitting on the roller drum being pushed down by the bolt head riding over it. As its being pushed down it’s pulling the belted round behind it into the star wheel because it has no where to go. So it cannot go all the way down, it’s now in a bind and something has to give. This is happening because of the difference in the round spacing, they are too close together! If you pull the belt out after checking this out you will see the first round that the bolt head rode over dented on top, then inspect the 2 rounds behind it and you will see dents on the case shoulder from the star wheel. When you tried to pull eject that live round by pulling your cocking handle back you should have felt a lot of resistance coming back.
We at RDTS have over the years developed a fix for the feed mech that makes your HK21 shoot reliable with both M-60 links and MG3 belts. It involves modifying the star wheel and a few other tweaks so the choice of what to use is yours. We have lately incorporated this mod in all our builds. Add RDTS’s cocking handle modification that eliminates broken cocking handle pins and supports while at the same time doubles the cocking travel of your 21 to absolutely crack that baby open and you are now definitely enjoying that RDTS 21EUG!
Excuse our blatant plug
Ralph at
www.RDTS.com
!!!
