I recently built a 9mm PCC...and I love it. However, I had 1 issue that was bugging me, the LRBHO (Last Round Bolt Hold Open) wouldn't work!

Initially right after I built the rifle it worked about 80% of the time.  I started looking at my rifle alot closer and what I realized is my Glock 19 Gen 5 mags were not pushing the catch up far enough.  To the point where I could insert the mag with my action open and just add a little upward pressure on the mag and see the bolt catch raise up another 16th of a inch (approx).  So I opened the magazines and stretched out the spring in the magazine, reassembled, and tested....they all have a little extra pressure to push that LRBHO on the Spikes lower up and catch the bolt every time.  So my take away is to experiment with some other Glock compatible mags to find ones that work better or just make sure I clean and test them before IDPA matches.

In any case, hope this helps anyone with this issue.









Parts List:
- Spikes Tactical 9mm PCC Lower (Glock Version)
- Aero Precision Upper
- Faxon BCG
- Faxon 16" Barrel
- SIG Romeo 5
- Timney PCC Single Stage Trigger
- Magpul MOE Grip (w/Kydex Fin for CA Compliance)
- Strike Industries:
  - Gridlock Handguard
  - Enhanced Buffer Tube
  - Stock w/Fixed Stock Conversion Kit
  - Enhanced Castle Nut
  - Ejection Port Cover
  - 9mm King Comp muzzle break
  - TI Riser Mount
  - Pivot & Rear Takedown Pins
  - Charging Handle
  - Ambidextrous Safety Switch
  - Forward Assist (for aesthetics)
  - Curved Forgrip (not in image)
  - Oppressor (not in image)

Final price tag was around $2,000

I just looked at the Spikes 9mm lower and LRBHO system. It looks like the worst mechanism I have seen on any 9mm lower.

Then I stumbled upon this:

https://www.ar15.com/forums/AR-15/New-to-PCC-builds-Looking-for-answer-about-LRBHO-/15-732906/#i7765934

I have the same Spikes lower, Aero upper.  LRBHO works with all size Glock mags.  Very positive engagement. The "bent wire rod" cantilever looks unconventional but has been working without issues.

I screwed around with my QC10 small glock lower for a couple of years............not reliable at all....maybe my luck. My final analysis was it worked.....it worked when you didnt want it to and it wouldnt work when you wanted it to...........I removed the parts and have not looked back..............LRBHO is not that big of a deal for me.............