Double Diamond dedicated Sub Gun 9mm AR15 Lower? Pics inside

**mr h** · 01-06-10, 15:02

hi,

i pretty new to posting here but saw this thread and wanted to jump in. first off, i will disclose that i am friends with the owner and a sales rep/beta tester for the company that is building these lowers.

fortunately i get to test out new product and i will say this one is made well and alot of effort went into the receiver design, the feed ramp parts and the bolt catch. is just a matter of time in waiting for the plater to get the finish right on the dedicated magazine well parts and for a final decsion to be made on how to address the c product/colt magazine bolt catch issues. right now its set up for colt pattern mags but the c product mags use a different mag follower and won't catch the colt pattern. he is thinking about designing his mag catch that will work with both. then they will start shipping.

as for the mag well bevel, its my opinion that the smaller mag well and bevel makes for easier mag changes than the standard 223 mag size. YMMV though.

looks like DDLES beat me to it on the post......

**DDLES** · 01-06-10, 16:36

I can see the question of magazine compatibility arising from Mr.H’s post. So, I would like to take a second and clarify the magazine compatibility of our 9mm lower.

We have (or had) two options for the bolt hold open.

Option #1 was to use an AR-15 standard bolt catch that comes in every lower parts kit. To do this we have a custom part that goes into the lower and contacts the magazine follower and pushes up on the standard bolt catch.

Option #2 was to use the Colt pattern 9mm bolt catch (the one with the long finger). We would use a spacer instead of the custom part mentioned earlier and the lower would be the same. This way a lower could be configured ether way, with AR-15 bolt catch or Colt 9mm bolt catch.

Initial tests of the Colt pattern bolt catch looked good. Upon further testing magazine compatibility issues were discovered. Old Colt (Metalform with plastic followers) magazines and Promag magazines would work without issues, but C-Products and new Metalform (with metal followers) would not activate the bolt hold open consistently. And in one test gun the Colt pattern bolt catch broke in the first range session.

We have at this point decided to hold off and not offer the Colt pattern bolt catch. We have a solution for the dedicated 9mm bolt catch but it will take some time to release it.

The AR-15 bolt catch compatible system works perfectly with ANY magazine we have tried. Old or new Metalform, C-Products and Promag all functioned perfectly with the AR-15 bolt catch option.

**Bulldog1967** · 01-06-10, 16:38

This thread is relative to my interests!

**BJV** · 01-06-10, 16:46

Originally Posted by DDLES

Option #1 was to use an AR-15 standard bolt catch that comes in every lower parts kit. To do this we have a custom part that goes into the lower and contacts the magazine follower and pushes up on the standard bolt catch.

This sounds like a system similar to what Hahn has in their dedicated (installed from the top) mag block, which, in my experience, works very well.

Originally Posted by DDLES

The AR-15 bolt catch compatible system works perfectly with ANY magazine we have tried. Old or new Metalform, C-Products and Promag all functioned perfectly with the AR-15 bolt catch option.

Great to hear.

Jon, if that's you responding, thanks for taking the time to post this info. You've been great about responding to my questions via e-mail as well.