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First, a little history. About 3 years ago, I got DEEP into building AR based PCC pistols. I started with a 9mm with a mag well adapter in a standard polymer AR lower, Colt pattern mags, and a CMMG upper. It was a cheap build, except for the upper, but it worked great. I didn't really like the looks of the mag in the mag well with all that extra space and wanted something a bit more robust and that used more common mags. After awhile, lowers and carriers that used Glock mags started becoming more commons I wanted to start working on my next builds with some higher quality parts. Around that same time, I attended the first Triggercon in 2017and was introduced to Quarter Circle 10 (QC10).
QC10 manufactures PCC's as well as the parts needed to build your own, so I started working out what I needed and got all the QC10 parts from Rainier Arms to build a 9mm and a 40S&W using the same lower. They were perfect. Worked fantastically with ECS and standard Glock mags (not so good with the cheap Korean 50rd drums). They were accurate and very reliable. Here is the build list as best I remember it;
QC10 Glock 9/40 lower (built in mag release and BHO)
BCM LPK
MagPul MIAD grip
SB Tactical PDW brace
QC10 adjustable buffer
AR10 Coiled buffer spring (supposedly a heavier spring is needed for PCC's)
QC10 Upper receiver for the 9mm
NFA side charger for the .40
QC10 40s&w carrier/QC10 9mm carrier
QC10 10.5" 40s&w barrel/QC10 8" 9mm barrel
Midwest Industries 9" handguard/Midwest Industries 7" handguard
New Frontier Armory 4 prong flash hider 5/8x24 / KAK style blast deflector
Not the cheapest build, but I wanted to go with as much quality as I could afford.
Eventually I got a dedicated lower for the 9mm and put a DeadFoot Arms folding adapter and Shockwave brace on it (very cool!)
Last year I decided I wanted to do some biger bore. The smaller bore pistols worked great, so why not a .45 or a 10mm?
This time I started with a matched upper and lower I got from Brownells. Made by the same maker that does a bunch of different vendors such as New Frontier Armory and others. A 10" 10mm QC10 barrel, a NFA .40s&w carrier, BCM LPK and similar other parts to my original builds. It turned out looking great, so I expected it to work just as well as my previous ones...boy, was I wrong.
Took the new 10mm PCC to the range, expecting the same performance I had been getting from my smaller bore's. I loaded up a Glock 20 magazine with Freedom Munitions 180gr 10mm and loaded it into the PCC. Pulled back the charging handle and SLAM...the round nosed, hard, into the top of the barrel. Shoving the bullet deep into the case. I ejected the round and managed to get the next one into the chamber, figuring it was all due to the newness of the gun. Managed to fire the round and had the next round do the same as the first. Bullet pushed deep into the case.
I proceeded to download the magazine to 5 rounds and managed to get three out of the five to fire. The others did the same as the first round. Frustrated, I went home and did some more research.
After looking around a bit more, there isn't much out there about 10mm PCC's, I decided to get an H3 buffer and a stronger buffer spring and see if that helped. It didn't. I rebuilt the PCC with QC10 parts (upper, lower, and carrier) thinking that maybe the original set was out of spec or something. Took it to the range, same problems.
Finally, I contacted QC10 with the problem. Wondering if there is something I did wrong with the build somewhere. I was getting ignition if the round fed, so it wasn't the internal springs (IMHO), I tried standard AR buffer spring and buffer with the same problem (and more recoil). I outlined the situation with QC10 and let them know the different troubleshooting I had tried.
Within a day or so, I got a response. Turns out, Freedom Munitions had never been tested with their builds so they couldn't verify that the ammo would work. Everything else I had done was correct, according to them, so it was probably an ammo problem. Something I hadn't considered. Now, I knew what I needed to do next.
I went to Low Price Guns and got some S&B and some Sig 10mm ammo and then hit the range. Now, instead of the 5% reliability I was getting, I was now getting 85%-90%. Still not as reliable as I wanted, but MUCH more than I was getting. Turned out the bullet profile of the FM rounds was not angular enough to feed (as far as it looked to me). So, I had found the solution, but not to the level I wanted. Now, I was thinking about selling the PCC and making it someone else's problem (not something I like to do). I'd had enough, but I just didn't want to give up just yet.
Fast forward to last week. The CMMG Banshee 10mm was all the rage on YouTube. All the guntubers were reviewing it and singing its praises, much to my annoyance. Finally, I watched the one that Military Arms Channel produced. In this one, he had some feeding problems and changed the buffer and mentioned that the SGM 10mm magazine springs were stronger due to how the 10mm fed.... "LIGHTBULB MOMENT"
Immediately, I ordered some G20 extra power Wolff mag springs from Midway USA and some SGM 10mm mags from GunMagWarehouse. If this didn't work, I was going to get my hands on a Vector 10mm eventually, so they wouldn't be wasted if this didn't work. When I got the springs, I changed them out in five of my mags and went to the range the next day.
I still had a butt load of Freedom Munitions, so I decided to load up a G20 mag to full capacity and see what happened. (haven't gotten my SGM's yet)
What happened was a miracle.
All 15 rounds cycled and fired.
So I did it again.
All 15 rounds cycled and fired.
And again, and again, and again.
I put about 150 rounds of FM down range along with some S&B without a hitch.
So, what did I learn? Not all ammo is created equal, sometimes the cheapest fix is the one that works, Wolff springs are amazing, Tim from the Military Arms Channel is a saint, and 10mm is a hell of a lot of fun to shoot!
I'll add some pics if anyone is interested. I just wanted to share this experience in hopes that if anyone else tries to go this route, they actually have somewhere to go to get some advice
.
I do have a .45 as well, but I haven't worked the bugs out on that one yet. I have some more Wolff springs coming for the G21 mags to see if that helps as it has the same problem as the 10mm did.
QC10 manufactures PCC's as well as the parts needed to build your own, so I started working out what I needed and got all the QC10 parts from Rainier Arms to build a 9mm and a 40S&W using the same lower. They were perfect. Worked fantastically with ECS and standard Glock mags (not so good with the cheap Korean 50rd drums). They were accurate and very reliable. Here is the build list as best I remember it;
QC10 Glock 9/40 lower (built in mag release and BHO)
BCM LPK
MagPul MIAD grip
SB Tactical PDW brace
QC10 adjustable buffer
AR10 Coiled buffer spring (supposedly a heavier spring is needed for PCC's)
QC10 Upper receiver for the 9mm
NFA side charger for the .40
QC10 40s&w carrier/QC10 9mm carrier
QC10 10.5" 40s&w barrel/QC10 8" 9mm barrel
Midwest Industries 9" handguard/Midwest Industries 7" handguard
New Frontier Armory 4 prong flash hider 5/8x24 / KAK style blast deflector
Not the cheapest build, but I wanted to go with as much quality as I could afford.
Eventually I got a dedicated lower for the 9mm and put a DeadFoot Arms folding adapter and Shockwave brace on it (very cool!)
Last year I decided I wanted to do some biger bore. The smaller bore pistols worked great, so why not a .45 or a 10mm?
This time I started with a matched upper and lower I got from Brownells. Made by the same maker that does a bunch of different vendors such as New Frontier Armory and others. A 10" 10mm QC10 barrel, a NFA .40s&w carrier, BCM LPK and similar other parts to my original builds. It turned out looking great, so I expected it to work just as well as my previous ones...boy, was I wrong.
Took the new 10mm PCC to the range, expecting the same performance I had been getting from my smaller bore's. I loaded up a Glock 20 magazine with Freedom Munitions 180gr 10mm and loaded it into the PCC. Pulled back the charging handle and SLAM...the round nosed, hard, into the top of the barrel. Shoving the bullet deep into the case. I ejected the round and managed to get the next one into the chamber, figuring it was all due to the newness of the gun. Managed to fire the round and had the next round do the same as the first. Bullet pushed deep into the case.
I proceeded to download the magazine to 5 rounds and managed to get three out of the five to fire. The others did the same as the first round. Frustrated, I went home and did some more research.
After looking around a bit more, there isn't much out there about 10mm PCC's, I decided to get an H3 buffer and a stronger buffer spring and see if that helped. It didn't. I rebuilt the PCC with QC10 parts (upper, lower, and carrier) thinking that maybe the original set was out of spec or something. Took it to the range, same problems.
Finally, I contacted QC10 with the problem. Wondering if there is something I did wrong with the build somewhere. I was getting ignition if the round fed, so it wasn't the internal springs (IMHO), I tried standard AR buffer spring and buffer with the same problem (and more recoil). I outlined the situation with QC10 and let them know the different troubleshooting I had tried.
Within a day or so, I got a response. Turns out, Freedom Munitions had never been tested with their builds so they couldn't verify that the ammo would work. Everything else I had done was correct, according to them, so it was probably an ammo problem. Something I hadn't considered. Now, I knew what I needed to do next.
I went to Low Price Guns and got some S&B and some Sig 10mm ammo and then hit the range. Now, instead of the 5% reliability I was getting, I was now getting 85%-90%. Still not as reliable as I wanted, but MUCH more than I was getting. Turned out the bullet profile of the FM rounds was not angular enough to feed (as far as it looked to me). So, I had found the solution, but not to the level I wanted. Now, I was thinking about selling the PCC and making it someone else's problem (not something I like to do). I'd had enough, but I just didn't want to give up just yet.
Fast forward to last week. The CMMG Banshee 10mm was all the rage on YouTube. All the guntubers were reviewing it and singing its praises, much to my annoyance. Finally, I watched the one that Military Arms Channel produced. In this one, he had some feeding problems and changed the buffer and mentioned that the SGM 10mm magazine springs were stronger due to how the 10mm fed.... "LIGHTBULB MOMENT"
Immediately, I ordered some G20 extra power Wolff mag springs from Midway USA and some SGM 10mm mags from GunMagWarehouse. If this didn't work, I was going to get my hands on a Vector 10mm eventually, so they wouldn't be wasted if this didn't work. When I got the springs, I changed them out in five of my mags and went to the range the next day.
I still had a butt load of Freedom Munitions, so I decided to load up a G20 mag to full capacity and see what happened. (haven't gotten my SGM's yet)
What happened was a miracle.
All 15 rounds cycled and fired.
So I did it again.
All 15 rounds cycled and fired.
And again, and again, and again.
I put about 150 rounds of FM down range along with some S&B without a hitch.
So, what did I learn? Not all ammo is created equal, sometimes the cheapest fix is the one that works, Wolff springs are amazing, Tim from the Military Arms Channel is a saint, and 10mm is a hell of a lot of fun to shoot!
I'll add some pics if anyone is interested. I just wanted to share this experience in hopes that if anyone else tries to go this route, they actually have somewhere to go to get some advice
. I do have a .45 as well, but I haven't worked the bugs out on that one yet. I have some more Wolff springs coming for the G21 mags to see if that helps as it has the same problem as the 10mm did.
