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RPD Bolt Carrier Mods for the DSA Rec?

9K views 21 replies 4 participants last post by  Dirty Harry 
#1 ·
Any info and, or drawings would be great!
 
#2 ·
What FCG are you using? Might make a difference for some of the stuff.


But to get the carrier to fit the receiver, need to remove about .040" off the bottom of the rails. Don't forget to take off the part that hits the firing pin first, and the sear catch/notch needs to come off.
I'll put up a couple pics tomorrow, I think I got them from Pirate, but at least you can get started on the little I gave you so far.

I'm working on mine now, and was planning to put up a rough build tut after I get it done.
 
#4 ·
Coils, Is the measurements the same for a WLA or Stan's system? I haven't decided which to use. Also, I'm guessing if the the sear catch needs to come off regardless what type FCG is used on a striker set-up?
 
#5 ·
The info I got was from Stan, he said his semi parts are almost the same as WLA's, he just had a few minor mods done that he believes are improvements. So to answer your first question, yes they are the same for both WLA and Stan's.

Yes the sear catch needs to come off, this is one of those ATF requirement things, you should do this and cut off that part that hits the firing pin first.
That 3/8" groove that goes from the sear catch to the ejector port is clearence for the semi sear or striker catch(which ever you want to call it).

The only semi FCG I've seen are striker setups, there's the Vector (which I feel is complicated) and the WLA design which is also the same style as Stan's.
 
#9 ·
And the .0625 seems awful small. I don't even think there is a pin that small included with the FCG kit. Mine was drilled to .120 IIRC.
I was getting ready to mention this, that .0625" is wrong, that's the same as 1/16" and there's only one pin that size that is used for the disconnector. The pin that should be used there is like 1/8" and what HairyToe said does fit if you measure for it.
 
#10 ·
Update
The .0625" hole is 1/16" and if you use that size the measurement in the pic is right, just go buy a 1/16" roll pin. If you use the pin that comes in the semi FCG you need to lower the hole, like HairyToe mentioned, since the pin is larger.
 
#12 ·
I finally have my receiver and trigger bar. After getting tired waiting for a friend to get involved in a re-weld, I ordered the last receiver Stan had in stock. Thanks for the pics in your other thread Coils. The pics help put into perspective the semi conversion machine work needed. I still have some questions before I start the mill.
 
#13 ·
Sorry to hear about waiting for your friend, but glad to hear you got a receiver, I'm sure you'll be able to sell the demilled receiver later.

I'll try to watch in case you ask for any advice
 
#14 ·
First few questions; must the locking flaps be modified? I fondled a friends RPD he built on a DSA receiver. He told me the locking flaps MUST be machined shorter to be considered semi by the abc boys. True? I understand what must be done to the lower to fit the receiver and accept the trigger bar. I'm also aware of all the mods needed to the bolt carrier. I'm building on the Project Guns design and noticed in one of his video's that he was drilling into the lower from the rear (where the stock mounts), why is that? Is the trigger required to be modified?

Enough for now.....
 
#15 ·
He told me the locking flaps MUST be machined shorter to be considered semi by the abc boys. True?
False. The only things that need to be modified is the carrier and the lower.
But I have seen a few people that had to mod theirs to fit properly. They might have been welded receivers though?




he was drilling into the lower from the rear (where the stock mounts), why is that?
I'll have to check it out later, tried to go to his site but it wasn't loading.
The only thing I can think of is for the striker spring, I had to touch up the hole that the recoil rod goes through a little so the striker spring wouldn't bind, I just used a stone in the dremel and it didn't take much.
If you can post a link where you seen the video




Is the trigger required to be modified?
I'll check into this, but if I remember right, a pocket needs to be made on the one side for a spring. I'll look for the pic(s) I took.
 
#17 ·
Glad to hear your making progress

Here's a couple threads from WG, one is the long one you already found. And the second one is mine (also look how I trimmer the lower to fit the receiver and still keep the serial number), there's pics of the trigger mod but I still need to find the info on it.
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Page two of this thread has the FCG hole diagram I used, save it to your pc
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#19 ·
I'll look for the pics I took, and the post I made when I did mine, I'll post it here.

For the trigger bar, I was told to help line things up is to line the notch on the trigger bar up with the safety. That did help a little for finding the spots for the pin holes.
 
#20 ·
For the trigger bar, I was told to help line things up is to line the notch on the trigger bar up with the safety. That did help a little for finding the spots for the pin holes.
I'm referring to profiling the 'nose' of the trigger to interact with the disconnector. After I reviewed what I read on a persons blog I realized he was only cleaning up the smoothness of the FCG. Heres a link to one of the best build tutorials I've found.

pharmory: Semi RPD Build [Part 3] - Lower, FCG
 
#21 ·
I didn't do anything to my trigger other then the cut out for the spring.
I modded the disconnector (or wedge) that the trigger pushes against, mine was long and wouldn't reset when you released the trigger.

It might be easier if you could post a pic of yours.
If you look at this thread again at reply 64 I have two clear pics of mine before I modded it, you can see how close the disconnector is to the trigger, and reply 69 has a pic of one that has a gap between the diconnector & trigger.
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I also came across this, Pirate is mentioning how to fit them together, don't know if it will help or not.
http://www.gunco.net/forums/f294/semi-rpd-fcg-60221/



And that's a nice tut that guy put together, thanks for posting it, he explains it well too. And yes it looks like he mainly just polished the parts.
Also if you go down near the bottom of that tut link, the pic above the video shows his FCG installed. You can see how he has a small gap between the trigger and disconnector, mine didn't have this and that's what I had to mod on mine to get it to function.
 
#22 ·
Looking through my bookmarks to determine best practice to press the barrel and set headspacing..... started this way too long ago. I did learn something on Stan's semi trigger. A lot of people (myself included) have noted issues with the trigger hanging after the disconnector disengaged the trigger. In my case the nose of the trigger was wedging itself in the front radius of the trigger bar slot. Judicious filing of the corners relieved the trigger from hanging. I also had to shorten the face of the disconnector that the trigger pushes against.

Now to decide how best to set headspace......
 
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