So you don't even have to flip down the loading tray or anything? Fascinating...

 

I open the feed mechanism to clear out the last link as I always add an empty link at the end of all my belts, which are just 20 rounds each (w/o starter tab). I add the extra empty link at the end to make it convenient at the range for subsequent longer belts as necessary. Since I'm not loading the old way, it’s just a matter of click, drop, inspect, and pop the feed mechanism back up in place w/o having to engage the top cover down onto the belt and inspecting to see if the round is properly aligned ‘in battery’. Almost always, that empty link I add to each belt drops out on the bench when the feed mechanism drops.

IMHO, 20 round belts with an empty link at the end is perfect if you have a burst trigger pack as I add the starter pull tabs there at the range; adding the 21st round or subsequent 42, 63, etc. belts with added round between belts for 3-shot burst (tack driving) function that this fine weapon platform is capable of.

Hats off to Mike Otte for such a fine operating and accurate weapon.

 

I like them. How much are they ?

 

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I found the DM-150 starter tabs online for $3 each. They were listed as "M-60 starter tabs".

Tagging this for info on completing the ones that I bought.

Thanks TF!
The MULE

 

This may jump around a bit. I'll focus on the drilling/routing of the starter tab link first. 'Have to get up early, so will continue tomorrow on what I use to easily remove/disassemble/assemble the starter tabs and bend the first M27 link.

...

I started with a Size 35 (.110) drill bit to make a pilot hole and then step up to a No. 30 (.128) bit. Note these drill bits aren't found at any local hardware store; those are wood/soft metal grade; the bits I use are industrial grade aircraft extension drill bits; I get 'em off eBay (Cleveland or Eclipse brand are some of the best). I made a simple tab holder by using two small wood screws in the adjacent tab slot (I recommend this unless you like tabs spinning like a helicopter blade when the drill initially punches through).

When drilling steel, use a sharp/new drill bit and drill slowly and apply lots of pressure; drilling fast will burn out the drill bit quickly.

Next, I took a piece of 3/4" plywood and cut a slot through both sides with the help of my table saw and gravity; flipping the board over to cut just a saw blade-size slot in the board. This will be my slot cutting guide. I fitted the tab with the hole to the slot and ground out a small detent where the tab loop can fit in; this to keep the tab flat. Two screws added while aligning the tab hole in the slot.

Next step was to simply use the round needle file in my drill and while drilling on slow to medium speed, saw it back and forth; the slot in the board will keep the needle file on track. Be careful as you approach each end of the slot as you don't want to go too far. I use a flattened M27 link to drop in and check the slot for fit. Note that the M27 link tab actually gets wider near the transition point (as shown below).

I then clean up the slot using a flat and square needle file; this to get some of the jagged edge off and to make the oval slot flat on one side (shown in the last picture). You will need to file the side near the tab loop to essentially make the slot meet the loop; this is how the added M27 link will turn/move loosely around the tab loop. A quick fit check with one of the M27 links ensures free movement about the tap loop end.

 

It's obvious that you have machine shop experience with the way that you approached the project. You've given me a perspective on the project that I think wiil help me a great deal. Oh, and I'll have to get some good drill bits like you mentioned.
Thanks!
The MULE

 

Disassembling the DM-150 Starter Tab 'Links' can be a PIA in itself; here are some tips.

I use a couple scrapers that I got from Lowes/Home Depot. One has the metal end on it for use with a hammer; this is key to initially open the small loops on the tabs as the metal is seriously tough. Once the scraper is 'in', just bend the loop enough to remove the adjacent link.

To remove the end M60 link, you can either use the above procedure or use a metal cutoff tool. My DeWalt with a thin diamond blade cuts the M60 link quickly. Now the links can be individually modified for use with M27 links as previously shown.

Bending the links is easy with the use of a metal rod that is approx the same diameter as a 5.56 casing; this to hold the link secure and keep it from bending during the forming of the small tab. I use a 1/4" hex bolt that is about three inches long; this seems to be a good diameter to form the tab; you can use a drill bit for this purpose too. Tap the link almost closed with a small ball peen hammer; leaving enough gap for installing the starter tab link. I use a small piece of thick phenolic block material; using the edge and corners to form the tab as necessary.

Reassemble the tabs and tap the loops shut. M27 Link(s) Starter Tab now complete.

 

Making correct M13/DM-6 Starter Tabs for a 21E platform is much easier, but finding M13 'Left' Starter Tabs can be a problem. Brownell's had HK M13 starter tabs but they recently discontinued them and took them off their site for some reason; probably after I called them about a backorder I had on these that was almost a year old; price for each was around $12.00. I was able to find these same starter tabs online at D&D Guns in W.Virginia; these don't come with the M60 tab which I find is a plus. I still use the small links from DM-150 starter tabs to build these as just installing a M13 link in the starter tab is just too short for a 21E feed mechanism (IMHO). I take it these M13 Left Starter Tabs were originally made for HK21 (not HK21E) platforms.

Using both M13 starter tabs and DM-150 starter tabs, I made some longer starter tabs that are perfect for the 21E platform.

And I figured out what to do with at least one of the leftover parts from the DM-150 starter tabs sets...