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MBX PCC Comp Feedback


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Mbx knows how to design a comp where most others don’t. Whatever bullet you use don’t use fmj or coated it will clog the comp and it’s a pita to clean out. 

 

Ill elaborate on the comp, mbx uses channels facing rearward, when the explosion of gas comes out it drives the gun down. Most companies base comps with the gas coming out as aerodynamic. It’s an explosion of gas not aerodynamics. 

 

 

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My experience the the MBX comp (I have their PCC) was it didn't seem to affect muzzle movement much when shooting a 147gr bullet that made a PF of 135K. Once I moved to a 115gr bullet making the same 135K PF, I perceived a smaller muzzle/dot movement with an increased amount of felt recoil. I'm using Alliant e3 powder, 3.7grs for the 115gr Berrys bullet IIRC.

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I use jhp, cmj or plated. I like 115 because it’s snappy recoil. Powder and bullet weight are user preference everybody likes something different. To work the comp gassy powders are better wsf,hs6, accurate 5 to name a few I’ve tried. 

 

The picture below is the lead I cleaned from my comp after using fmj. It took me two days of letting soak in a ultrasonic and chiseling out. Weight is listed in gn 

C8A2012A-10C0-41D2-96E3-52EBDEC2F115.jpeg

Edited by Bwillis
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What PF are you running with HS6?

I have AA7, CFE Pistol and maybe Longshot I will try with 115gr. HP’s
With a 16” barrel
My only priority is for the dot to return as fast as possible. Minimal movement is nice.



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Had a standard JP comp, swapped to a custom Briley comp, then back again to JP comp, then to MBX comp. Difference is really small but I believe the MBX comp is best. It’s only based on what I see in terms of dot movement and of course my grip style etc. Running 147gr plated and jacketed bullets 

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My head is spinning still WTF:)
What am I missing??? HELP!

Is open pistol logic applicable to PCC or not???

Right or wrong?

To work any comp you need gas.
You get more gas with more powder.
You shoot a 115 vs. 147 to use more powder (more gas).
Is the comp is designed correct that extra powder is turned into a flat shooter with minimal dot movement due to a well designed comp.
so why run a comp and 147 gr. Bullet?
Less powder= less gas=less comp efficiency.
Am I missing something.
I mean no disrespect to anyone that is happy with their PCC load.
If you don’t run a comp or don’t care about making it efficient the I get a a 147gr. With a fast powder possibly.

Trying to speed up my personal load development, is my goal with my new arrived today MBX Comp.
thank you all
Interested in best gassy powder for working this MBX comp withFMJ 115’s



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Less powder-less recoil- the comp will be less efficient. But you stay flat. I don’t use 147 because I shoot uml and have to take shots out to 200 147s nose drive at 100 

The number one way to tune your pcc is load to springs and buffer period. 

Xantos posted a formula in one of these threads to equate the force gas exerts on the comp. Try messaging him for that formula. 

My load now is 4.6gn wsf 115jhp 1.12 oal-1210 fps 139 pf 

 

Edited by Bwillis
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14 hours ago, oteroman said:

My head is spinning still WTF:)
What am I missing??? HELP!

Is open pistol logic applicable to PCC or not???

Right or wrong?

To work any comp you need gas.
You get more gas with more powder.
You shoot a 115 vs. 147 to use more powder (more gas).
Is the comp is designed correct that extra powder is turned into a flat shooter with minimal dot movement due to a well designed comp.
so why run a comp and 147 gr. Bullet?
Less powder= less gas=less comp efficiency.
Am I missing something.
I mean no disrespect to anyone that is happy with their PCC load.
If you don’t run a comp or don’t care about making it efficient the I get a a 147gr. With a fast powder possibly.

Trying to speed up my personal load development, is my goal with my new arrived today MBX Comp.
thank you all
Interested in best gassy powder for working this MBX comp withFMJ 115’s



Sent from my iPhone using Tapatalk Pro

"Is open pistol logic applicable to PCC or not???"

It is in a Locked breach gun (MPX). 

 Not so much in a Blowback as they are counter productive to each other.  What drives the comp increases the bolt velocity and felt recoil in a Blowback gun, you can address that with system weight and spring rate 

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I've wondered before if that's what a comp is actually doing to the feel of the recoil (especially on a shorter 11-14" barrel).....a la, it's relieving the back pressure so it doesn't hurl the BCG back as hard/fast, and that's perceived as countering muzzle lift?

Edited by MoRivera
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For what its worth, Im new to PCC and am shooting a MBX Pro Series with the 14" barrel and comp.I shoot for Orr Tactical Custom Guns and Ammunition. We worked up a PCC load based on felt recoil.We shot our standard 115 pistol ammo and were at 1297 fps w/ 147PF. We worked up a 100 grainer at 1310fps w/ 131 PF.While the 115's feel good , the 100 grainers feel a little more " carbine " like BUT with very little dot movement. Oh, Im running the Green recoil spring in my buffer system. As stated above.....it's more about personal preference on felt recoil.

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  • 3 weeks later...
On 3/22/2019 at 2:32 PM, assaultthesalt said:

For what its worth, Im new to PCC and am shooting a MBX Pro Series with the 14" barrel and comp.I shoot for Orr Tactical Custom Guns and Ammunition. We worked up a PCC load based on felt recoil.We shot our standard 115 pistol ammo and were at 1297 fps w/ 147PF. We worked up a 100 grainer at 1310fps w/ 131 PF.While the 115's feel good , the 100 grainers feel a little more " carbine " like BUT with very little dot movement. Oh, Im running the Green recoil spring in my buffer system. As stated above.....it's more about personal preference on felt recoil.

What powder and weight?

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8 minutes ago, JZELEK said:

What powder and weight?

We're using a Berry's 100 grain hollow base projectile.Hodgdon CFE Pistol. I can't remember how many grains.Too many numbers running through my head. LOL  I shot a match weekend beforelast and one guy on  my squad said he was watching my gun as I shot.....He said he could see the gas coming out and the comp working , as the gun was running flat. :) 

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I run the MBX mid weight barrel that has the pinned comp. I use RMR 124gr jacketed bullets loaded with 3.9 of tightgroup and I really like the comp, it seems to really mitigate muzzle rise. 

 

I have no issues cleaning it, I use Slip 2000 Carbon killer and will just pretty much fill the mop up and let it sit for a few minutes then spray it out with an aerosol cleaner and it always removes any build up of carbon or lead that may be present.

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  • 4 weeks later...
On 3/19/2019 at 1:33 AM, Bwillis said:

I use jhp, cmj or plated. I like 115 because it’s snappy recoil. Powder and bullet weight are user preference everybody likes something different. To work the comp gassy powders are better wsf,hs6, accurate 5 to name a few I’ve tried. 

 

The picture below is the lead I cleaned from my comp after using fmj. It took me two days of letting soak in a ultrasonic and chiseling out. Weight is listed in gn 

C8A2012A-10C0-41D2-96E3-52EBDEC2F115.jpeg

Have you tried running a drill bit through the comp to make sure the bullets are not scraping the comp?  Mine had to be drilled out a little because the holes were not exactly even with the barrel.

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@S&W627shooter I’ve never had accuracy issues with my mbx setup to think I needed to test for bullets striking the comp. The lead wasn’t even diminishing the guns accuracy, but my dot track was way off of what it should have been. I compared my comps inner dimensions to a new combs dimensions and realized I’m awful at cleaning guns.  

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