CMMG Guard tuning (9mm)

[Ryan N]

I'm looking to build out a 2nd PCC.  My first is a QC10 standard blowback with a 308 Carbine spring and Kynshot buffer.... it's been fantastic.  I was considering a CMMG bolt and barrel but now rethinking that due to reliability issue. 

 

I'm curious to hear any updated reviews on the CMMG RDB.   

[RickT]

I'm running the a CMMG in 9mm, the current version which followed the "Guard".  The only reliability I've had relates to the ejector spring which CMMG has updated to what the call the MK10.  I wouldn't count on more than 2000 rounds without replacing this spring with the first indication being a change in the ejection pattern.  Normal ejection with my loads is at about 4 o'clock.  When this starts moving forward a spring change might be in order.  If I were competing with a CMMG I'd carry a spare bolt or bolt/carrier.  FWIW I'm running an A5 tube and one of the Kynshot buffers which is a good combination.  Disclaimer: I'm not a PCC expert but they are a lot of fun to shoot.