Making a dsm hand guard retainer

For those that have a lathe or access to a lathe, retainers can be made from steel core plugs(aka freeze plugs, Expansion plugs). I used 1 1/8” plugs, bored out the ID a few thousands, turned the OD down, bored the center then shortened it. My biggest problem is cutting the ring exactly in half. I should be able to get two retainers from a ring but seem to alway be off a few degrees. I’m strictly a very amateur as a machinist but I’m pleased with the outcome. I finished one by heating and dipping in BLO and another with cold blue, either was acceptable to me.

Installed on rifle

How are you attaching it to the rear sight base?

They don’t attach, they’re interstitial. Nice work, good idea!

Thanks, the idea wasn’t mine, I had read years ago of using a plug.

oldwing said:

For those that have a lathe or access to a lathe, retainers can be made from steel core plugs(aka freeze plugs, Expansion plugs). I used 1 1/8” plugs, bored out the ID a few thousands, turned the OD down, bored the center then shortened it. My biggest problem is cutting the ring exactly in half. I should be able to get two retainers from a ring but seem to alway be off a few degrees. I’m strictly a very amateur as a machinist but I’m pleased with the outcome. I finished one by heating and dipping in BLO and another with cold blue, either was acceptable to me.

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Do you have a mill? If so turn an arbor that matches your freeze plugs, make two retainers, and use a slitting saw (.030" or so) to cut in half.

Here is another idea. You can make a jig using phenolic plastic using a CNC. The center slit is a hacksaw blade guide. Red Circle is the retaining ring, ovals on either side are designed to allow a screwdriver to pop the retaining rings out once the rings are cut in half. Design is something I just kinda threw into Autocad, so it's rough and would need the dimensions adjusted. I have access to a CNC and might be able to construct it--depending on if my contact has the correct bits to cut the plastic. Again, design is rough and I'd need to adjust it, might be able to simplify the design if I spent more time on it.

Fal grunt, no mill here. I ended up turning this stepped piece of aluminum bar. Took a couple of tries but I ended up with a 180 degree slit using hacksaw. Works well. I may have a few retainers to sell. I’m going to try each on several different DSMs to verify fit.

oldwing said:

Wreck tangle, no mill here. I ended up turning this stepped piece of aluminum bar. Took a couple of tries but I ended up with a 180 degree slit using hacksaw. Works well. I may have a few retainers to sell. I’m going to try each on several different DSMs to verify fit.

Click to expand...

Didn't even thing of the jig you posted looks good. Once you try them out, I'd be willing to purchase a few.

If of interest I listed some in the classified section