Colt 9MM SMG adapter roll pin placement

[B y r o n]

As the title states, I'm looking for information (dimensions) for where the three roll pins are placed in the lower receiver. I've searched the site and the Internet to no available except for photographs. I sent an e-mail to R&D Precision who built the original adapters and waiting for a response. I've also sent an e-mail off to Blowback9 to see if he has any information.

My adapter is on backorder so don't have it in hand to take any measurement or get better visual clues. I'm hoping some of you might have already done this and may be able to help.

 

[kl3309]

Is the adapter that you're waiting on pre-drilled for the three pins or does it have a different retention scheme?

 

[B y r o n]

Is the adapter that you're waiting on pre-drilled for the three pins or does it have a different retention scheme?

No, it is not drilled for the pins. It has a button head screw on the top and two set screws on the bottom.

 

[Cascade Hemi]

I believe the RO633 and RO635 magazine adaptor holes were drilled with the adaptor fixtured in the lower.

 

[kl3309]

No, it is not drilled for the pins. It has a button head screw on the top and two set screws on the bottom.

View attachment 8562847

Then no reason to through-drill the receiver unless you just want "the look." Modern manufacture should give better tolerances so there shouldn't be a need to locate the adapter with pins.
Have you seen the Blowback9 webpage on how he installed one with the two angled set-screws? Also showed a pic of an alternative where the block was located with a screw straight through the front of the receiver.

 

[B y r o n]

Then no reason to through-drill the receiver unless you just want "the look." Modern manufacture should give better tolerances so there shouldn't be a need to locate the adapter with pins.
Have you seen the Blowback9 webpage on how he installed one with the two angled set-screws? Also showed a pic of an alternative where the block was located with a screw straight through the front of the receiver.

I have seen the Blowback9 pages and videos. When he mentioned that the angled screws would slide, the pins seem to be a more solid solution. I also saw the hidden screw behind the front take down pin but it is only one small screw.

I picked up a few Anderson lowers for about $40 each so drilling a couple 1/8" holes in it doesn't sound so bad.

 

[cas6969]

Don't pin it from the get go. Make sure it works, you may need to fiddle with the height to get it to work right.

 

[B y r o n]

Don't pin it from the get go. Make sure it works, you may need to fiddle with the height to get it to work right.

Good advise!

 

[B y r o n]

Here are a couple pictures of pin placement. Once I have all the parts in hand placement might be more obvious.

 

[kl3309]

Here are a couple pictures of pin placement. Once I have all the parts in hand placement might be more obvious.

View attachment 8563293

View attachment 8563296

If you're not trying to clone-fag it then it doesn't matter where the pins go. Just mock it up and see where you have clearance. You could even drill and tap multiple locations and use opposing numbers of set-screws.

 

[918v]

I like this:

https://hahn-precision.com/ar-15-top-9mm-adapter/

 

[dogman]

I had a Hahn adapter in a standard AR lower receiver and it worked just fine drop in.

 

[B y r o n]

So I took the plunge.

I used a 1-1/4" long pin closest to the trigger opening and 1" at the front of the receiver because I couldn't find a 1-1/8" pin. Pin closest to the trigger opening was easiest to place. It simply goes in the center of where the ridges meet. I placed the front pin center line even with the upper edge of the magazine catch opening for the horizontal. For the vertical center line I put it inline with the screw holding the adapter together. I used stub drills because they are stiffer than standard length bits because they are shorter. Pre-drilled with 1/16" first then followed with 1/8". I installed the pin closest to the trigger opening before drilling the front pin hole.

Don't have to worry about the adapter slipping now!

 

[B y r o n]

The finished product, at least for now: