How reliable are colt mag guns?

[MemphisMechanic]

Assuming a quality lower such as a QC10, of course...

 

Why do Glock magged guns seem to be 90% of the USPSA PCC guns out there? As someone who doesn’t have any Glocks anymore, I am not biased since I would have to buy mags anyway. The magazines are also such a relatively minor expense that +\- $100 to set up a few of them isn’t really a factor.

 

I like the aesthetics of the vertical mag versus the sloped Glock mag... but mainly? I’m digging the ability to slap a traditional AR ambidextrous mag release on my gun, since I’m a lefty.

 

I might just be the first one to buy a CMMG guard upper and a QC10 colt mag lower and see if I can get the two to play nice (some machine work might be required, sure). Assuming you guys are getting the mags to run with boring reliability at 40+ rounds.

Edited April 17, 2018 by MemphisMechanic

[L3324temp]

CMMG also makes a straight 9mm colt lower. I have one and it runs flawlessly.


Sent from my iPhone using Tapatalk

[BartCarter]

My 2 Colts (one pistol, one carbine) runs reliably.  My CMMG Guard runs reliably.  I have built 4 other Colts, all run reliably.  If you build your own, you might have to fit or massage parts.

 

If I build any more, they will be CMMG Guards with a hydraulic buffer.  (You need to use a 3.25" carbine buffer, not the 4".) I would certainly build them using CMMG Guard barrel, BCG, upper and lower.  They did their homework and these parts really work together.

 

I don't reload, I shoot Fiocchi 115 FMJ.

[Alvin]

I've got four colt mag AR's at the present time...all are Hahn mag block inside a regular .223 lower since I already had the lowers set up with good triggers.  No problems with any of them.  I did manage to buy a bunch of Metalform(Colt) mags back when PSA had sales on them.

[Silverscooby27]

My colt works fine...until I try to put an extension on it, which is a problem for PCC. I have 2 GMR-15s that run like tops. There are a few guys locally running colt mags but they all required some serious fitting and polishing, etc.  to work, and I would say still not as reliable as Glock mags in my opinion. Also, $100 for mags?! Not even...way more than that for all the goodies for either colt or Glock. Plus, don’t forget the belt and mag pouches.  Oh yeah, and optics and mounts...Dang this is getting expensive, haha. If you want lefty mag release maybe you should check out Ruger PCC as an option too?

[Xanatos903]

Lefty colt mag PCC shooter here. Mine's been super reliable with the only problems coming from me doing stupid stuff like limiting the bolt travel and not doing QC checks on my reloads. I run a Taccom-spliced 32-20 magazine for 54 reloadable, but also use everything from a 32 rounder with a +10 extension to the 20 round ASC mags. Everything works, drops free, and reloads with my ambi mag release. I've had to do absolutely no tuning of my magazines, they just work. 

 

The Glock PCCs seem to be more prone to feeding issues, sometimes requiring an additional feedramp to be added to the upper receiver. They also require you to file away at the base of the magazine to remove flashing left over from the manufacturing process. Seems like every Glock mag I've put a basepad on has eventually had the follower bind up at the transition from basepad to magazine body because of that flashing. But they remain popular in PCC because the aftermarket support is second to none, and everyone has a Glock and a stack of magazines anyway. 

Edited April 17, 2018 by Xanatos903

[Aircooled6racer]

Hello: The Colt mag lowers from QC10 work great. I only use Metalform magazines, Taylor Freelance base pads and the Taccom coupler. I also use the Wolff extra power springs on the magazines that have extensions. Thanks, Eric

[Tampa-XD45]

My cheapo PSA Colt blemished lower is 100% reliable.  I run Metalform and ASC mags with no problems.  I've never tried to run the Pro-Mag garbage mags. 

[bwikel]

I'm using colt mags with a conversion block and mated to a CMMG guard upper. It took some tweaking to get it to run well but it gave me everything I was wanting in a PCC. With a dedicated colt lower running a Guard upper you would of course have to remove the ejector and then modify the mags to drop them down in the magwell as the CMMG bolt is same dimensions as a normal AR bolt and will drag on the mag. I run mags from 20 rounds to 66 rounds with no issues the only exception is you cannot mono pod off the mag or it will double feed. 

[MemphisMechanic]

29 minutes ago, bwikel said:

I'm using colt mags with a conversion block and mated to a CMMG guard upper. It took some tweaking to get it to run well but it gave me everything I was wanting in a PCC. With a dedicated colt lower running a Guard upper you would of course have to remove the ejector and then modify the mags to drop them down in the magwell as the CMMG bolt is same dimensions as a normal AR bolt and will drag on the mag. I run mags from 20 rounds to 66 rounds with no issues the only exception is you cannot mono pod off the mag or it will double feed. 

 

Extremely encouraging. This is really good to know, and it meets my expectations. Are we talking roughly 1/16” - 1/8” of height difference?

 

I pretty much assume you carefully filed the notch open until the bolt would clear the feed lips, and it runs reliably like that.

 

The double-feed is a result of driving the magazine up into the gun too far, I assume?

 

What is your extended magazine setup? Welded two mags together, or something else? I’ll be looking for rough 40-55 rounds in a magazine to give me plenty of leeway in a 32 round steel stage.

 

How does the gun eject and reload for classifier scenarios?

Edited April 17, 2018 by MemphisMechanic

[MemphisMechanic]

1 hour ago, Aircooled6racer said:

Hello: The Colt mag lowers from QC10 work great. I only use Metalform magazines, Taylor Freelance base pads and the Taccom coupler. I also use the Wolff extra power springs on the magazines that have extensions. Thanks, Eric

Excellent info as always Eric.

 

I should be able to mount a traditional AR ambi-mag release on that lower. Correct?

Edited April 17, 2018 by MemphisMechanic

[bwikel]

2 minutes ago, MemphisMechanic said:

 

Extremely encouraging. This is really good to know, and it meets my expectations. Are we talking roughly 1/16” - 1/8” of height difference?

 

I pretty much assume you carefully filed the notch open until the bolt would clear the feed lips, and it runs reliably like that.

 

The double-feed is a result of driving the magazine up into the gun too far, I assume?

 

What is your extended magazine setup? Welded two mags together, or something else? I’ll be looking for rough 40-55 rounds in a magazine to give me plenty of leeway in a 32 round steel stage.

I had to drop my mags down 0.10 in. to clear the bolt and yes I filed and fitted until it cleared. Material was removed from the top side of the mag catch slot.

 

The double feeding is due to the up and down play I created by opening up the mag catch slot and it pushing the mag up in the magwell where it will strip more than one round at once.

 

My extended mags consist of a 32 rd metalform with a printed taccom extension for 40 rds. and two 32 rd. metalform mags spliced together for 66 rds. I don't run ASC mags as I had no luck getting them to run reliable even when my set up was straight blowback. 

[Aircooled6racer]

1 hour ago, MemphisMechanic said:

Excellent info as always Eric.

 

I should be able to mount a traditional AR ambi-mag release on that lower. Correct?

Hello: Yes you can just like this one. Thanks, Eric

[MemphisMechanic]

The doesn’t help a lefty.

 

 

 

...But it’s good to know that the standard AR mag button widgets do Indeed work.

 

 

Edited April 17, 2018 by MemphisMechanic

[blaster113]

I've run two Colt mag lowers; first a CMMG then a QC10.  Only feeding issues I had were with a Taylor Freelance+10 basepad equipped 32 round mag with mousefart 147 grain loads, or from shit reloaded ammo (yeah, my fault), and trying to stuff a full 32 round mag into the gun and load with the bolt closed (solution: either load with the bolt open or download so the top round isn't pushed up into the ejector). 

 

The mousefart loads in the TF basepad mag made 130 or so pf, barely cycled the gun, but caused a yard sale (shit everywhere aka double/triple feed).  If I use lighter bullets loaded hotter the mag was flawless.  Evidently the mag doesn't like mousefart loads with heavy bullets and my MBX buffer.  Going to use 115's at 135-140pf anyway from now on and adjust the powder charge so the TF equipped mag feeds 100%..  Using regular 32 or 20 round mags, the carbine is a sewing machine.  I'd recommend a Colt lower without hesitation.

[38superfan]

My current ar is a mutt based on a factory cmmg mk9 lower with a parts upper. The only issue I have is mags not dropping free. Hoping the magwell will smooth up. Other than that,its great.

[BartCarter]

36 minutes ago, 38superfan said:

My current ar is a mutt based on a factory cmmg mk9 lower with a parts upper. The only issue I have is mags not dropping free. Hoping the magwell will smooth up. Other than that,its great.

 

I have built some of the same with the CMMG MK9 lower.  I took the mags that didn't drop free and used a vice to make them a couple of thousandths thinner.  Doesn't take much.  I have done this to over 30 Metalforms.  (I have friends that need help too. )

 

Be gentle and go a little at a time until you find the right dimension.  Very easy.

 

I also use a dry lubricant, EEZOX, on the magwell and mags.

[Jetskidawg]

My Rock River LAR-9 is extremely reliable and I use only Metalform mags.  Literally zero failures in about 2,500 rds.  The only downside to the Colt SMG pattern is reloading, which should be rare if you have extensions (I use TF +10's on 32 rd mags).  In the case of classifiers with mandatory reloads the mags can be downloaded enough to relieve that tension.

[BartCarter]

21 minutes ago, Jetskidawg said:

My Rock River LAR-9 is extremely reliable and I use only Metalform mags.  Literally zero failures in about 2,500 rds.  The only downside to the Colt SMG pattern is reloading, which should be rare if you have extensions (I use TF +10's on 32 rd mags).  In the case of classifiers with mandatory reloads the mags can be downloaded enough to relieve that tension.

 

I sometimes shoot with a fellow that has shot SMG Colts for more than 30 years.  When I had trouble loading a mag against a closed bolt, he told me to load to an odd amount of rounds.  An even amount puts a round in just the wrong position for the mag catch to seat easily.  That made a noticeable difference for me.

[38superfan]

Thanks for the tip Bart! I'm still trying to get my ASC mags to fit. 

[BartCarter]

33 minutes ago, 38superfan said:

Thanks for the tip Bart! I'm still trying to get my ASC mags to fit. 

After I made sure of the width of my ASC mags, I found that the odd round side of the mag lip rubbed on my bolt.  I carefully filed that lip until the bolt had clearance.  Problem solved.

 

When "fitting" mags, you have to look where they are rubbing and "conform" them to your lower.  I kept checking and "adjusting" until I had zero problems with the Colts (Metalform) or ASC mags.  They are really not exactly the same, but they can be made to function the same.

 

When finished, I test them and only use them in matches when they run through 3 full mags with no problems.  Knock on wood, it has been a long time since I had a mag problem. 

[BartCarter]

BTW, not every mag needs to be "adjusted." 

[Tampa-XD45]

16 hours ago, BartCarter said:

 

I sometimes shoot with a fellow that has shot SMG Colts for more than 30 years.  When I had trouble loading a mag against a closed bolt, he told me to load to an odd amount of rounds.  An even amount puts a round in just the wrong position for the mag catch to seat easily.  That made a noticeable difference for me.

Same here.

[Jetskidawg]

23 hours ago, BartCarter said:

 

I sometimes shoot with a fellow that has shot SMG Colts for more than 30 years.  When I had trouble loading a mag against a closed bolt, he told me to load to an odd amount of rounds.  An even amount puts a round in just the wrong position for the mag catch to seat easily.  That made a noticeable difference for me.

Great tip, thanks!

 

[alanm]

I have had zero feeding issues from my spikes, colt lower.