Did you not read any of the existing threads on this?
https://www.ar15.com/forums/Industry/9mm-Guard-Barrel-and-BCG-working-with-Colt-mags/145-286362/
https://www.ar15.com/forums/ar-15/Thoughts-on-the-CMMG-Guard-/15-713060/&page=11
Several people including my self are running the Guard system with Colt mags and in all cases, nobody is modifying the bolt. In one case, someone grinded on the bottom of the carrier but myself and others have not had a need to do that.
In regards to making a drop in setup for Colt mags, they already answered you question on page 4 of the last link I pasted above,
Link Posted: 11/14/2017 10:14:44 AM EDT
Report
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By m6z:
No, they are completely different systems.
View All Quotes
So existing CMMG customers with your 9mm Colt lowers won't be able to use your new RDB uppers?
Will you be offering a Colt mag RDB gun?
Correct, the two systems are incompatible.
Eventually we will circle around to the Colt pattern lower, but current focus is getting the other 5 or 6 calibers developed and released.
CMMG, Inc
PO Box 369
Fayette, MO 65248
660-248-2293
www.cmmginc.com
[email protected]