A 9mm pistol caliber carbine that takes MP5 magazines? That intrigued me enough to build one. This QC5 came as a fully-built pistol with arm brace. I took it apart and replaced some components: 1) Replaced SB Tactical arm bracewith a Gearhead Works Tailhook, 2) replaced QC10 handguard with a sawed-off Centurion Arms rail, 3) replaced A2 type flash hider with a Spike’s Tactical Barking Spider 2, 4) added front and rear sights, 5) replaced A2 type pistol grip with Magpul MOE K2, 6) Added sling.
Some observations:
Both upper and lower fit and finish are excellent.
Captured spring and detent for rear receiver retaining pin are a nice touch.
The bolt and carrier are one unit.
I tried a Vltor MUR-1A upper and found that mags wouldn’t seat. The QC5 upper has bevels that allow MP5 mags to insert all the way to the bolt.
The bolt has a plug that adds weight, probably for proper cycling…
The plug is secured by a roll pin. I asked QC10 if the plug could be removed in order to accomodate a Law Tactical Folder Stock Adapter extension. Danny at QC10 said that the plug weight can be removed, but that I should cut it to length and reinsert it to accommodate the Law Tactical extension while retaining part of the original weight of the bolt.
During function tests, I found that the Geissele Super Dynamic 3-Gun trigger doesn’t work. Danny said that the SSA and SSA-E triggers are the only ones that have been found to work with the QC5 setup.
A fully-loaded MP5 mag won’t seat without considerable force in a bolt-forward condition.
There is no last round bolt hold open (LRBHO). Danny said that’s because MP5 mags weren’t designed for LRBHO.
The QC10 proprietary buffer is heavier than a regular AR-15 H3.
The lack of LRBHO is a bit of a deal breaker for me. Having to load up less than full mags just so they can seat into the mag well when the bolt is foward is another. Off to the range this weekend! I’ll have to figure out some funky manual of arms for the QC5.
It’s reliable. No stoppages or feeding issues from 500 rounds through it. The lack of last round bolt hold open got old very quickly, though. You have to load mags with 28 rounds instead of 30 so they will seat with the bolt forward. Manual of arms is quite dissimilar to that of an HK MP5K. I haven’t shot the QC10 in a while and stuck to my MP5K instead.
I don’t have any experience with the QC10 Glock mag version, but based on the manual, it looks like it has last round bolt hold open, unlike the MP5 mag type, which doesn’t.
I have owned a QC10 Glock for about three years now…………for two years I screwed around with the LRBHO and found it to be unreliable………you have to have magazines that will make it work………I only used Factory Glock magazines………some work and some don’t………I replaced the magazine springs with wolf extra power springs, some work and some don’t…………I bent the metal tab that engages the magazine follower, some work and some don’t…….Then the bolt locks open with a round left in the magazine………The tolerances in the magazines are ever so slightly not the same and for the LRBHO to work…….they have to be spot on…If you pick up 10 factory glock magazines, not all will work………I spent the better part of two years worth of range trips trying to get this set up to work…………With that said, I bought a CMMG MK9 and it works everytime…………
Is everybody having this LRBHO experience with Glock mag PCC’s? I’ve got a CMMG Mk9 (Colt mag) that runs like a sewing machine, but I’ve been eyeing a CMMG MkG (Glock mag) to use as a suppressor host.
I love the Glock QC10 ………its the most used firearm I have…next to my G19, it runs like a top, gobbles up everything…with the exception of the LRBHO, which wont work now since I removed the parts………I love this thing………Ive had several discussions with people at QC10………I once told them I bet you have a lot of people complain about the LRBHO on these lowers and the response was, Well most lowers don’t even have it………that maybe true………but their system is not the better “mouse trap”. You are trying to get a pistol magazine to work in a carbine is what I have heard too………Im over the fact that it is not reliable…………On the other hand, it is a well made and finished lower, runs like a top and is handy………I load one round less than the full capacity of glock magazines and they lock in with no trouble on a closed bolt…………I also have a CMMG MK 9 that sits in the safe………
