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School me on PCC


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Longtime reader but this is my first time posting. I'm going to get into USPSA PCC and need a 9mm carbine. I've done some research including review past PCC threads, but I could use input from the hive mind. My budget is <1400 total including mags, extensions, belt pouches. I already have a good optic.

 

Here are my thoughts, please correct me if I have made any mistakes, I'm here to learn!

1) I shoot glock but I have no 33 rounders. Should I go colt or glock for the lower? Either way I'll purchase two or three mags and two or three extended baseplates. Colt gives you potential ambi and better angle plus slightly cheaper mags. On the other hand I have no plans to give up shooting glocks and commonality is nice. I have seen both colt and glock at local matches.

2) The CMMG radially-delayed system is appealing, should I get this and add a better buffer (but which one ??) I have read several threads and it seems like the recoil reduction over straight blowback is marginal but there may be some reliability advantage. Whats the latest thinking on this? Does anyone have solid experience with both and recommend one over the other?

3) I don't like Sig and don't want an MPX. I also don't want a Ruger PC carbine.

4) If CMMG Guard isn't the bees knees, I will just assemble a standard AR9. I've seen some threads with build lists, but here are the components I'm leaning toward:

-Taccom complete 14.5 upper with extreme feed ramp, extreme bolt, and pinned comp

-QC10 lower

-taccom multistage buffer with short stroke kit OR blitzkrieg hydraulic buffer with JP 308 spring (again, if you have experience with both please post your thoughts)

5) JP GMR15 is probably awesome but seems overpriced for a 9mm blowback, especially if I start swapping out parts. My 5.56 competition rifle cost significantly less than a GMR15.

6) I understand that ammo can affect the choice of operating components, so here's my situation. I do not handload, and I don't plan to start. I shoot pretty much exclusively blazer brass 124 or sometimes 115. I'd be open to switch to a different factory ammo if someone gave me a compelling logical reason to do so, but I've had zero malfunctions in thousands of rounds and i can get it cheap so I see no reason to switch.

 

Please give me some feedback on colt vs glock lowers, CMMG radially delayed vs straight blowback, and AR9 build components. I can figure out the ergonomic stuff like triggers and handguards on my own, but I need input on the operating components as I have no experience at all with the AR9 platform. I want something where the dot settles fast between shots, it's fun to shoot, and it's reliable. A lot of the PCC threads are a bit dated (I missed the PCC boom in '17-18) and it seems like new stuff has come out, so I'm curious to hear what the latest "state of the art" build might look like.

 

Thank you!

 

 

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Qc10- I had issues with their floating ejector. Fix feeler gauge shimming ejector to the right and forward. Then rockset once it ejected 100%. 

 

Bolt iron city rifle work- I had issues at first with the extractor, Jason without hesitation listened to my complaint found a solution and resolved my issue.  I’m now 8k deep on 1 bcg without any issues and 2k on another. Top notch customer service. Ar15 ramp design works with most milspec triggers also has the notch for shooting innovations barrel and the slickest pvd coatings. 

 

Barrel- mbx or shooting innovations- mbx throated to accept 1.15 oal innovations 1.13. Mbx has one of the best feeding cones on a barrel, shooting innovations has a nice ramp( I’ve never had any issues with misfeeds either barrel both are accurate hold pasters at 25 with a red dot. Adrian and Andy stand behind their products. 

 

Rail- iron city rifle works or smoke composite both are top notch service, both offer lightweight durable products. 

 

Blitzkrieg 5015 hd and ss

 

Pins,detents and springs I went cmmg 

 

Most places you can call and talk to the owners about what they sell. Blitzkrieg, iron city, shooting innovations, smoke composites. Mbx  is email only but always a fast reply. There are also a lot of members with vast knowledge that I’ve learned a lot from about pcc load data, what works best why ect Ect.

 

oh and  brownells often has Glock mags for $25

 

ben Steoger pro shop has the best price on +10 tti gen 2 extensions. I recommend rounding the tips on the follower and knocking the slag out of the bottom of the 33s

Edited by Bwillis
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Gmr 15 all the way, all you need is a lite weight handguard if anything, bye the time you build a good Frankenstein gun you will save little. The GMR has great trigger , great barrel , and they run . There’s a  reason they sell more then anyone else quality and customer support.

If you build quarter circle upper and lower JP everything else , my son runs a Ck Barrel in his custom build . Good luck with your new toy whatever you decide.

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Don’t handicap yourself with the budget, getting a gun you will not be happy with , spend your money on the gun get the belt later, you can get a couple of 33 round ets mags and a 27 and build from there. Oh yea go Glock not colt .

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I am a fan of running a PCC that runs, so that pretty much rules out budget builds.  By the time you build a complete and running unit you would not be too far ahead of an out of the box model.  Of those, I suggest JP or MBX.  I also suggest Glock factory mags.

 

Good luck!

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Thanks for all the great feedback, please keep it coming. I'm going to go with Glock over Colt and switch to 115gr based on replies thus far. I'm especially hoping to hear from those who have tested the CMMG radially-delayed as I want to start with the optimal operating system.

 

Allow me to clarify my budget and thoughts on the JP GMR15 a little bit. I have no doubt that if I got one it would run perfectly. I read that something like half of top competitors are using them. That or the MBX pro series would be a great turnkey solution. However, I don't think either one is the "perfect" PCC out of the box. Another great example is the limcat Tron that just came out. I understand why these are built and priced how they are, but I believe based on what I've read here that you can get a functionally (not aesthetically) equivalent PCC for less if you're willing to tune it a bit. If I had GM skills and was playing for money, or I was depending on it to save my life, I'd go JP. Neither is the case for me.

 

For example, I think the JP bolt and barrel are great but I don't see the SCS recommended much. From what I read here, most are recommending the blitzkrieg hd5015 hydraulic buffer plus heavy spring with added wave spring and spacers. As far as the upper receiver, I don't see any advantage to one brand over another unless it's a side charger. For the lower, it seems like QC10 is one of the most commonly recommended. I also would not choose the JP or MBX handguard, trigger, stock etc so again I'm paying top dollar for components I'd want to replace. The only complete factory gun I ever bought where I didn't replace a single part is the Armalite M15-3GN, which I only bought because I got it for such an amazing price that I could not assemble a similar rifle cheaper.

 

In general I think a build from parts is riskier with the AR9 where there is no agreed-upon spec, but some combinations of parts must have potential to run reliably. As with the AR15, if you don't choose the parts carefully your Frankengun will experience tolerance stacking or outright incompatibility between components. Overall I'm leaning towards a lot of Taccom parts because they seem to be putting out innovative, quality components at a very reasonable cost and having the majority of operating components come from one source should cut down on problems.

 

Again, I have no experience and this is all based on reading the forum so please do step in and set me straight if I'm off base!

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anyone else experienced the problem B.Willis commented on --- """" Qc10- I had issues with their floating ejector"""""   I just received a Qc10 lower which I noticed has the floating ejector..  I have not started my PCC build .  ..   wonder if I have made a mistake ordering a Qc10 lower...

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1 minute ago, cecil said:

anyone else experienced the problem B.Willis commented on --- """" Qc10- I had issues with their floating ejector"""""   I just received a Qc10 lower which I noticed has the floating ejector..  I have not started my PCC build .  ..   wonder if I have made a mistake ordering a Qc10 lower...

 

My issue was if I leaned to the left or forward the ejector would lean left or forward and miss the case. Also the ejector is cut at an angle throwing brass down easy fix with a dremel.  I called Rudy at Macon armory nice guy( if you google search qc10 floating ejector issue the original fix will lead you to Rudy) call him talk to him for over an hour come up with a $2 dollar feeler guage at autozone cut to fit shim it to the right and back. Get it ejecting 100% and rockset it in. Easy fix here’s Rudy’s number 478-474-2990 

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56 minutes ago, JGT said:

Thanks for all the great feedback, please keep it coming. I'm going to go with Glock over Colt and switch to 115gr based on replies thus far. I'm especially hoping to hear from those who have tested the CMMG radially-delayed as I want to start with the optimal operating system.

I run a guard barrel and bolt on a AR9 I put together. I have also run a blowback system. The guard has some advantages over a straight blowback gun out of the box with recoil impulse. It also takes out potential ejector problems you see in blowback as well as you won't have to worry about what trigger is compatible since it uses carrier very similar to a standard AR. Another advantage is it uses a DI AR firing pin and I don't know of anyone that has broken one, even with hard hitting triggers. I would suggest you get the complete CMMG guard and tune the buffer system to your shooting style. With the glock mags you have you will probably only need to add a couple big sticks and could use the same mag pouches you have now for glock mags. 

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Having built and competed with two different AR-9's, a franken-guard, and now two MPX's I'll give you my take:

 

 

17 hours ago, JGT said:

do not handload, and I don't plan to start. I shoot pretty much exclusively blazer brass 124 or sometimes 115.

 

I know you said you don't like Sig, but you would be the PERFECT candidate for the new MPX PCC. It (and all MPX's)  likes factory ammo and is by far the softest recoiling platform with factory/hotter ammo.

23 minutes ago, bwikel said:

I would suggest you get the complete CMMG guard and tune the buffer system to your shooting style.

 

Yep. DO not franken-AR a guard. Not worth the hassle. Buy a 16" Guard complete setup. Shoot it. Read up on your buffer/spring alternatives and try them as you're able.

 

The CMMG platform is not worth upgrading to if you already had an AR9 and/or were reloading, but given your circumstances, I would suggest:

1. MPX (I know, but I've run and own all 3 platforms.... I stuck w/ MPX and own two now)

2. Guard (Buy, don't build... and I build all my AR's)

3. Franken-AR. Build a cheap one. Learn what works for you, buy used parts, etc. but will spend more money if you want to shoot optimized ammo i.e. Atlanta Arms, Syntech PCC ammo, etc.

Edited by Acer2428
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I have a question. I'm not trying to talk you into one because I don't have one, but why not mpx? I'm thinking of getting one, but i'm interested in all the pros and cons of them. What is it that you don't like, other than price, which I agree they all seem too high.

Oh, one more added thing to think about for later. I know you said you don't reload, but down the road you might think about it. With a pcc you will burn through a lot of ammo. It's just so much fun .

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11 minutes ago, egd5 said:

I have a question. I'm not trying to talk you into one because I don't have one, but why not mpx? I'm thinking of getting one, but i'm interested in all the pros and cons of them. What is it that you don't like, other than price, which I agree they all seem too high.

Oh, one more added thing to think about for later. I know you said you don't reload, but down the road you might think about it. With a pcc you will burn through a lot of ammo. It's just so much fun .

I HATE Sig products... But recently started shooting an mpx. It's phenomenal. No dot movement. None. Has some reliability quirks. Needs to be cleaned more regularly that a straight blowback... But it's a great performer. 

Edited by Dirty_J
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My issue with Sig and the MPX may or may not be totally rational, and I don't want to speak ill of anyone's chosen tool, but here are my own personal reasons why I'm not getting an MPX. I have no doubt that it is the softest shooting, but it does seem like Sig has a tendency to launch products before they are ready. Between the initial problems with the MPX, the 320 drop test fiasco, and the 365 striker drag / broken firing pin problems I do not have confidence in Sig as a brand. I'm never an early adopter, as you can tell from the fact that my first PCC will be purchased in 2019! I'm sure the majority of the issues have been ironed out by now, but nonetheless, I don't fully trust them. I have also read that the MPX is still not the most reliable platform. I've seen them go down at local matches several times (anecdotal evidence, I know) and I still read about people having problems with them on various forums.

 

Finally, I don't like the lack of commonality with other platforms and being stuck relying on Sig for most parts. I know there's some parts interchangeability and aftermarket support but certainly not as much as AR9's or even the CMMG Guard. That means prices will stay high and there may not be as much innovation or iterative improvement over time. Business competition is what has gotten prices, reliability and performance to where they are today in 5.56 AR's. That's another reason I am finding it hard to spend much on a PCC, the price to performance is still several years behind the market in AR15 or precision rifle.  I like the MCX/MPX operating system and if I could buy one from another company, or ideally multiple other companies, I probably would. From Sig, I will have to pass.

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OK, thanks to both of you. I have a Colt 6951 pcc now and it has done nothing but run fine for the last 2 years or so that I've had it. The only thing I've done internally is a different trigger and Taccom buffer. I don't NEED another, but I just kinda want something different to try. I'm getting GAS (gear acquisition syndrome).

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JGT.....I was in your shoes....kinda. I just saved a little more and bought a MBX Pro Series.It was between that or the JP.......MBX was in stock so I got it ( MBX has good customer service also ) .Presently waiting to zero in next week and start running her. :) 

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MBX or JP is how I would go, buy once and cry once and enjoy reliability without tinkering to get there. JP GMR15 Ready Rifle pricing with discount code isn't that much more than a MBX, that was enough to get me to buy a second one for my GF to use and be my backup.

Edited by ABQautoxer
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I am a hotrodder, so I am all about the journey of the build

 

I would like to have an mpx, but I really love doing the homework, building the gun, and creating something that works well and is exactly how you choose it to be.

Plus if done correctly you might save a buck or two.

(But two dollars is probably all you will save LOL)

Edited by Startingover
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Well I was going to start a why do I need a JP GMR15 post but I see there is no consences on them.  I currently run an ATI with a hiperfire and am pretty happy with it.  I don't know if a gun twice the price of it will give that much better results.  I mean I'm not gonna be a better/ faster shooter with it.

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7 hours ago, Andyk said:

Well I was going to start a why do I need a JP GMR15 post but I see there is no consences on them.  I currently run an ATI with a hiperfire and am pretty happy with it.  I don't know if a gun twice the price of it will give that much better results.  I mean I'm not gonna be a better/ faster shooter with it.

If yours runs good, with no hiccups.

You have won 95% of the battle with these things.

The rest is weight or ergonomics.

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I didn't purchase one, but I have seen people run the ck arms, which is a little cheaper than the MBX.  I run an MBX and love it.  I have 3 pcc's and the glock mags are less finicky.  I would suggest those.  The mags also seem to be much more readily available and cheaper. I also have a QC10 side charge.  The convenience is great. Unfortunately the charging handle broke on the first stage and forced me into running the MBX.     

 

I had an issue with the cmmg mk9 and that left a bad taste for cmmg for me.

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1. MPX (I know, but I've run and own all 3 platforms.... I stuck w/ MPX and own two now)

2. Guard (Buy, don't build... and I build all my AR's)

 

You've shot both?  

My only reference thus far is a Scorpion side by side with the MPX on practice stage runs, which clearly the MPX had much less dot bounce/movement off target.

Thus, I'm curious if there is really that much noticeable difference between the MPX and Guard, since it is well-documented that the Guard is less recoil/sight movement compared to a typical AR9 (not a tuned AR9) which are said to be closer to Scorpion-level.

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2 hours ago, AustinWolv said:

 

 

 

You've shot both?  

My only reference thus far is a Scorpion side by side with the MPX on practice stage runs, which clearly the MPX had much less dot bounce/movement off target.

Thus, I'm curious if there is really that much noticeable difference between the MPX and Guard, since it is well-documented that the Guard is less recoil/sight movement compared to a typical AR9 (not a tuned AR9) which are said to be closer to Scorpion-level.

 

I currently own all 3 platforms.

 

I have a few AR-9's pre-USPSA.

I have a tuned up AR-9 I started USPSA PCC with
I have a franken-Guard I built to compete with before I had the chance to run an MPX (wife now shoots it)

I have two Gen 1 MPX's (one SBR, one w/ taccom welded extension)

 

The Scorpion is a blowback design, same as an AR-9. With buffer and ammo tuning you can get an AR-9 to run SOFT or FAST, but the holy grail is BOTH. The MPX achieves this right out of the box (basically). The Guard is about 1/2 way between and MPX and an AR-9. 

 

I also had to have Memphis Mechanic ream the Guard barrel to run loads that plunk in my stock CZ barrels... So consider that expense and/or consideration. 

 

As a point of reference. I've told this story before:

 

I had built the Guard to compete with. I was out testing/chrono'ing ammo in it (135 Bayou over 3.3 clays iirc) and my buddy showed up with his Gen 1 MPX pistol. For S&G I loaded up some of my rounds and popped off a few rounds. The difference was night and day. I bought the MPX from him there on the spot. 

Edited by Acer2428
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