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Differences between Glock Lowers

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I've been doing research on components for an upcoming PCC build but am struggling to find information on any functional differences between different lowers.

 

For example I see the Quarter Circle 10 lowers recommended fairly frequently and are currently on sale for $225 QC10.

 

On the other hand a guy I shoot with has a Palmetto state armory PCC and has had no issues with it and their lower is only $120 PSA.

 

Are there any functional differences (beyond aesthetics and brand loyalty) between these two lowers?  I'm not opposed to paying a premium for for quality parts if they are objectively better but if I can save $105 on the lower and get the same performance I'd rather use that money to upgrade other components of the rifle.

 

The only thing I can tell that is different between the two from their descriptions is the QC10 has a LRBHO and the PSA does not which is not a deal breaker for me.  

 

 

 

 

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Generally when it comes down to Glock lower rigs running good, it has to do with the magazine angle in the lower. QC10, JP, etc., have the correct angle.

 

you can also compensate for the angle a bit by using a ramped barrel.

 

i have a couple of QC10 lowers, and recommend them.

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I have two PCCs using PSA billet lowers that run great. I'm sure the JP and QC10 are nice but if your on a budget I would not hesitate. The PSA billet I have are NFA built. As are many other 9mm AR lowers. 

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You will find the tolerances are different on different lowers.  for example, I have three PSA lowers (Forged, Gen2 & Gen3)  The forged will accept Korean mags and still have some wiggle room.  The gen2 will barely accept the mag without forcing it in, and the Gen3 will only accept it if I really force it.

PSA lowers were made by NFA.  The Gen3 (Im not sure)  

A lot of people will bash their stuff.  I only had one problem with my forged lower, and their customer service was top notch.  PSA gets a bad rap from people who pay twice as much.

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Hello: Some lowers are lighter than others as well. I like the QC10 because of the cutdown magwell area and they just run. I have Glock and Colt magazines lowers and they both work well. The lowers with very high round count around here are JP, Sig MPX and QC10 with some having over 50,000 rounds. I have over 10,000 rounds through one QC10 and only 3,000 on the other. I think some of the magic is in the lower but even more in the upper setup. Thanks, Eric

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18 hours ago, BigBamBoo said:

Generally when it comes down to Glock lower rigs running good, it has to do with the magazine angle in the lower. QC10, JP, etc., have the correct angle.

 

 

I've seen this mentioned a lot but with no real context.  I see QC10 touted as having the correct angle but don't see anyone mentioning which lowers have the incorrect angle.  Do the PSA lowers have a different angle compared to QC10 and as anyone actually measured them to quantify how they're different?

 

5 hours ago, stick said:

A lot of people will bash their stuff.  I only had one problem with my forged lower, and their customer service was top notch.  PSA gets a bad rap from people who pay twice as much.

 

This is one of my reasons for asking the question, I have a 5.56 AR built with mostly PSA parts and while they don't have all the bells and whistles they just plain work and were a great value for the money.  Like I mentioned before I don't mind paying more to get something that is demonstrably better but I hate paying extra just to have a certain brand's roll mark on the side.  

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I recall there was some lower that caused problems if the carbine was rested on the magazine. The magazine would move up, more than is good for functioning.

 

Any problems with that with anything currently available?

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I have a JP that is great and built another rifle with an NFA lower.  I liked the fact that the NFA did not use pins (uses threaded set-screw style pins) and included a upper/lower fit tensioner.  The NFA has the correct mag angle and I have not had any problem with Glock or ETS mags, they both fit snug and drop free.

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I have two carbines that use NFA lowers. They have been good for ~ 11,500 rounds combined with various Glock-brand mags. They work just fine.

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Check out the classifieds MikieM has a nice PCC for sale at what seems to be a good price.

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2 hours ago, sandrooney said:

Check out the classifieds MikieM has a nice PCC for sale at what seems to be a good price.

 

You can't buy the parts to build one for what he is asking...

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Biggest downside with the NFA/PSA lower is the slop front to rear of the mag/mag well
 

depending on your bolt, buffer, ammo, &  barrel combo
you may experience nose dive issues in worse case scenarios

 

 

videos worth watching on this topic:

 

 

 

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8 hours ago, mmlook said:

Biggest downside with the NFA/PSA lower is the slop front to rear of the mag/mag well
 

depending on your bolt, buffer, ammo, &  barrel combo
you may experience nose dive issues in worse case scenarios

 

 

videos worth watching on this topic:

 

 

 

 

It might be that the clearance is not consistent from gun to gun, or they adjusted that dimension, because mine is not that loose.   I only have one to check, and that is not any more statistically significant than the one example that Tim shows, but I am curious about what everyone else with an NFA is seeing?

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21 hours ago, L9X25 said:

 

It might be that the clearance is not consistent from gun to gun, or they adjusted that dimension, because mine is not that loose.   I only have one to check, and that is not any more statistically significant than the one example that Tim shows, but I am curious about what everyone else with an NFA is seeing?

 

I have a joe bobs/nfa lower. I just measured mine and at the bottom of a standard 33 round Glock mag, I have 1/4 inch play back and forth.  Same with my ets mags.  Bullet presentation does change a bit.

 

I placed a .034 thick shim on the back of the mag and got the movement down to 1/16th inch, but mags will not drop free. I’m assuming there has to be at least some play in the qc10s and jps. 

 

I have 2k rounds+ thru this gun and had no feed issues. Even shooting a couple uspsa and 2 gun matches with a MBX mini extension. 

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My NFA lower has never had a "jam" of any type.  It has had a broken firing pin, and an idiot that installs the primers sideways or upside-down, but no jams at all.  

 

I have various magazines from 10 rounds through 66 rounds.

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definitely seems to vary, between lowers.

 

I have both an NFA lower and a JP GMR-13

 

definitely depends on your whole setup as well.

 

I originally ran a JP upper & scs on the NFA lower.  every 5 rounds I would have a FTF or FTE.  switched to the JP lower and zero problems for the past 1000 rounds.

 

I now run a ramped taccom upper and an armaspec SRS on the NFA lower.  no problems for the past 1500 rounds.  

 

All on factory blazer ammo.

Glock factory & ETS mags.

 

I’d imagine hollow points and/or longer OAL’s will affect things as well

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Seems to me that if you by one company's components, you are probably good to go.  If you mix and max, you can be good or you may have problems with different tolerances or actual design.  After all, there is no mil-spec for 9mm Glock carbines, is there?  What is the price difference, a couple hundred dollars?

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Does anyone have any experience with the Matrix Arms lowers? They and some people on the internet claim it has 100% lrbho functionality. Would be looking to pair it with the PWS upper, KVP upper, or maybe a PSA upper if something appealing comes up. Is there another upper worth checking? Not interested in the Taccom "carbine" upper with short effective barrel length. 

 

I'm also wondering about the NFA/PSA lower with NFA lrbho side charging upper.

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If LRBHO is important to you, you might look into building a Colt mag gun.

 

They’re designed to activate the AR bolt catch; the back of the follower pushes straight up on it instead of requiring a complex linkage from the left front corner of the magazine.

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4 hours ago, MemphisMechanic said:

If LRBHO is important to you, you might look into building a Colt mag gun.

 

They’re designed to activate the AR bolt catch; the back of the follower pushes straight up on it instead of requiring a complex linkage from the left front corner of the magazine.

I've read about some reliability issues with the Colt mags 

 

It seems like the more I research the different options the more imperfect every pcc is 

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5 hours ago, MemphisMechanic said:

If LRBHO is important to you, you might look into building a Colt mag gun.

 

They’re designed to activate the AR bolt catch; the back of the follower pushes straight up on it instead of requiring a complex linkage from the left front corner of the magazine.

 

FWIW, I have had 100% function from the LRBHO on the NFA Upper.  That is a pretty easy way to get LRBHO if you want it and do not have and you can get side charging thrown in with it.

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On 5/27/2018 at 6:16 AM, stick said:

You will find the tolerances are different on different lowers.  for example, I have three PSA lowers (Forged, Gen2 & Gen3)  The forged will accept Korean mags and still have some wiggle room.  The gen2 will barely accept the mag without forcing it in, and the Gen3 will only accept it if I really force it.

PSA lowers were made by NFA.  The Gen3 (Im not sure)  

A lot of people will bash their stuff.  I only had one problem with my forged lower, and their customer service was top notch.  PSA gets a bad rap from people who pay twice as much.

So you’re saying I shouldn’t panic because my steel challenge PCCO gun is a PSA billet Gen2 lower with a 16” PSA upper?  

 

All it does is go bang and ring steel since I bought it May 12, 2017.  

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41 minutes ago, robert3405 said:

So you’re saying I shouldn’t panic because my steel challenge PCCO gun is a PSA billet Gen2 lower with a 16” PSA upper?  

 

All it does is go bang and ring steel since I bought it May 12, 2017.  

Don't panic.  My USPSA PCC is a forged lower with 16" upper.  

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On 5/31/2018 at 2:23 PM, polymerfeelsweirdman said:

I've read about some reliability issues with the Colt mags 

 

It seems like the more I research the different options the more imperfect every pcc is 

 

Reliability issues with a Colt style? Please share more about this. All the folks I know..including my two Colt style rigs, run 100%. I prefer them over my Glock style. The Colt’s seem a bit “smoother” cylcling than my Glock style. And I have one QC10 Colt and one QC10 Glock.

 Both with the exact upper, bolt, Buffers, triggers, etc.

 

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42 minutes ago, BigBamBoo said:

 

Reliability issues with a Colt style? Please share more about this. All the folks I know..including my two Colt style rigs, run 100%. I prefer them over my Glock style. The Colt’s seem a bit “smoother” cylcling than my Glock style. And I have one QC10 Colt and one QC10 Glock.

 Both with the exact upper, bolt, Buffers, triggers, etc.

 

Perhaps it was mag choice, but of course I read it on the internet and not first hand so it could have just been BS

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