Looks like CMMG is coming out with 5.7x28 AR conversions - Page 1

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[ARCHIVED THREAD] - Looks like CMMG is coming out with 5.7x28 AR conversions

Posted: 1/13/2020 8:06:19 PM EDT

Designed to work with standard AR lowers. 5”, 8”, and 16” barrels.

https://cmmginc.com/product/upper-group-kit-banshee-300-mk57-5-7-x-28mm-3-40-rd-mags/?utm_source=CMMG+Inc.&utm_campaign=274342951a-mk4_57_conversion_launch&utm_medium=email&utm_term=0_b49434befb-274342951a-20782757&mc_cid=274342951a&mc_eid=fe149308df

https://cmmginc.com/product/upper-group-kit-banshee-100-mk57-5-7-x-28mm-1-40rd-mag/?utm_source=CMMG+Inc.&utm_campaign=274342951a-mk4_57_conversion_launch&utm_medium=email&utm_term=0_b49434befb-274342951a-20782757&mc_cid=274342951a&mc_eid=fe149308df

https://cmmginc.com/product/upper-group-kit-resolute-200-mk57-5-7-x-28mm-2-4-rd-mags/?utm_source=CMMG+Inc.&utm_campaign=274342951a-mk4_57_conversion_launch&utm_medium=email&utm_term=0_b49434befb-274342951a-20782757&mc_cid=274342951a&mc_eid=fe149308df

Posted: 1/13/2020 8:25:59 PM EDT

[#1]

Could have been better if it used P90 mags.... or even an adapter for FN 5.7 mags. But it is a good sign that so many companies are jumping onto 5.7

Posted: 1/13/2020 8:29:54 PM EDT

[#2]

The 16" seems like an odd option, I can't think of a reason I'd want a 16" 5.7x28 vs a 5.56x45.

Posted: 1/13/2020 8:32:32 PM EDT

[#3]

Hopefully the next step is for them to come out with 40rd Five Seven mags.

Those would be a hit - useful in their purpose built 5.7 Banshee, as well as the FN Five Seven and MPA 5.7 MAC.

Posted: 1/13/2020 8:55:12 PM EDT

[#4]

Quote History

Quoted:
Could have been better if it used P90 mags.... or even an adapter for FN 5.7 mags. But it is a good sign that so many companies are jumping onto 5.7

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Suspect that it would be a lot more work to get their RDB system to work with the top feed P90 mags, plus would require a specific upper instead of what I presume is a standard AR upper, so likely more expensive.

Trying to decide between 5” or 8”. 5” is essentially the same as the pistols. 8” gets a velocity bump to get it closer to the P90.

Posted: 1/13/2020 9:51:21 PM EDT

[#5]

Kinda neat but kinda expensive. Pretty much the same as buying a new PS90, but without the cool factor and 50-round mags.

3x the price of a 5.56 AR?

No thanks. I'll wait for the Ruger PC Carbine 57, for half the price and shared mags with my pistol.

Posted: 1/13/2020 10:07:25 PM EDT

[#6]

Willi3d, is this something you want? If so, why?

Posted: 1/13/2020 10:19:52 PM EDT

[#7]

I clicked on the second link first and definitely read 140 round mag and was like no way!

Posted: 1/13/2020 10:20:36 PM EDT

[#8]

I like it. Basically I can have a 40 round 5.7 SBR for $600 or less. My concern would be the magazine reliability.

Posted: 1/13/2020 10:22:20 PM EDT

[#9]

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Quoted:
Willi3d, is this something you want? If so, why?

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Because I have a PS90, FN FiveseveN pistol, a Ruger-57, and a bunch of ammo. Also have a SBR AR lower, and this would allow me to have a 5.7 SBR without having to SBR my PS90, and it also comes threaded 1/2x28, so I can use my Rugged Oculus with it.

Posted: 1/13/2020 10:42:30 PM EDT

[#10]

Cool.

Posted: 1/13/2020 10:51:17 PM EDT

[#11]

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Quoted:
The 16" seems like an odd option, I can't think of a reason I'd want a 16" 5.7x28 vs a 5.56x45.

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It’s for those of us in states where we can’t have anything under 16”

Posted: 1/14/2020 1:00:54 PM EDT

[#12]

Quote History

Quoted:
It’s for those of us in states where we can’t have anything under 16”

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Quoted:

Quoted:
The 16" seems like an odd option, I can't think of a reason I'd want a 16" 5.7x28 vs a 5.56x45.

It’s for those of us in states where we can’t have anything under 16”

But if you're going to have a 16" then, why not have it in 5.56x45?

Posted: 1/14/2020 7:05:47 PM EDT

[#13]

Neat.

Wouldnt mind getting around to recreating this with a pistol...

Posted: 1/16/2020 1:34:22 AM EDT

[#14]

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Quoted:

But if you're going to have a 16" then, why not have it in 5.56x45?

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I want the 16" mainly to add back to testing since the PS90 got chopped :D

Posted: 1/16/2020 10:23:42 AM EDT

[#15]

man,

I'm all for more 5.7 stuff but thats pretty steep for an upper. I've got SBR lowers they could go on, but damn. I didnt give but $1000 for my PS90

Posted: 1/16/2020 10:28:38 AM EDT

[#16]

Quote History

Quoted:
man,

I'm all for more 5.7 stuff but thats pretty steep for an upper. I've got SBR lowers they could go on, but damn. I didnt give but $1000 for my PS90

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If you got a brand new PS90 for only $1000, you were very lucky.

Posted: 1/16/2020 2:11:44 PM EDT

[#17]

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Quoted:

If you got a brand new PS90 for only $1000, you were very lucky.

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True. Most new PS90's I see now are in the $1399 range.

Posted: 1/16/2020 6:54:15 PM EDT

[#18]

Quote History

Quoted:
True. Most new PS90's I see now are in the $1399 range.

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Quoted:

If you got a brand new PS90 for only $1000, you were very lucky.

True. Most new PS90's I see now are in the $1399 range.

Honestly. It wasn't NEW, but it was never fired and this was about 3 years ago. You can keep a close eye on gunbroker and catch deals from time to time.

I bought a STG-556 for 900 with 6 Mags.

Posted: 1/20/2020 6:03:56 AM EDT

[#19]

They are on the right path with this. One day I will have a 5.7 Colt MARS or KAC PDW replica.... one day.

Posted: 1/21/2020 6:41:32 AM EDT

[#20]

$900 plus for just the upper

I wont even consider one at that price.

Posted: 1/21/2020 9:47:03 AM EDT

[#21]

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Quoted:
$900 plus for just the upper

I wont even consider one at that price.

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Where are you seeing that? I see the 5” upper plus three mags is $800.

Posted: 1/24/2020 9:37:24 PM EDT

[#22]

good stuff. hope to see 10mm next.

Posted: 1/25/2020 8:26:12 AM EDT

[#23]

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Quoted:good stuff. hope to see 10mm next.

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??? The 10mm is already out.

Posted: 1/25/2020 8:57:49 AM EDT

[#24]

10mm magazine conversion?

Posted: 1/25/2020 2:37:42 PM EDT

[#25]

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10mm magazine conversion?

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Sry, I thought you meant 10mm RDB, my bad.

Posted: 3/19/2020 10:54:52 AM EDT

[#26]

Anyone own one of these? If so how do you like it - accuracy, reliability, any issues with the mag?

This is the one I'm thinking of getting:

https://cmmginc.com/product/upper-group-kit-banshee-200-mk57-5-7-x-28mm-2-40rd-mags/

I already have a few SBR lowers, so I could just drop this onto one. Then use my Surefire Mico can on it, for a handy little package.

Posted: 3/19/2020 6:55:52 PM EDT

[#27]

Quote History

Quoted:
Anyone own one of these? If so how do you like it - accuracy, reliability, any issues with the mag?

This is the one I'm thinking of getting:

https://cmmginc.com/product/upper-group-kit-banshee-200-mk57-5-7-x-28mm-2-40rd-mags/

I already have a few SBR lowers, so I could just drop this onto one. Then use my Surefire Mico can on it, for a handy little package.

View Quote

I have one, the 8” barrel upper. I put it on one of my SBR lowers. No problems with reliability, shot both SS196 and 197 factory ammo with no hiccups. Used a standard carbine buffer and spring. Pretty flashy with a bare muzzle. I ran a Rugged Oculus, but it started unthreading itself during shooting and ended up with an endcap strike, which ended the suppressed run. I’ve since put a Griffin minimalist FH on so I can use one of my 5.56 rifle cans, but haven’t gone back out yet.

Posted: 3/20/2020 9:12:50 AM EDT

[#28]

CMMG makes some cool stuff but damn if they don't think it's gold-plated.

Posted: 3/20/2020 9:20:00 AM EDT

[#29]

Quote History

Quoted:
Could have been better if it used P90 mags.... or even an adapter for FN 5.7 mags. But it is a good sign that so many companies are jumping onto 5.7

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This. 50rd p90 mags like the AR 5.7 had.

Posted: 3/20/2020 3:53:58 PM EDT

[#30]

I really want to build one of these 5.7 conversions, but using their bolt and barrel(a built upper is way to much anyway!). Along with wanting to try to make a side charger if possible. The main debate is should i try for super compact PDW and use a 5 inch barrel or average size SBR with the 8 inch barrel? Does anyone have an reliable numbers on 5.7x28 ammo thru various barrel lengths? By the inch doesnt have a 5.7 section last i checked. I also want to see the long term durability and reliability of the 5.7 mags

Posted: 3/20/2020 4:04:43 PM EDT

[#31]

Quote History

Quoted:
I really want to build one of these 5.7 conversions, but using their bolt and barrel(a built upper is way to much anyway!). Along with wanting to try to make a side charger if possible. The main debate is should i try for super compact PDW and use a 5 inch barrel or average size SBR with the 8 inch barrel? Does anyone have an reliable numbers on 5.7x28 ammo thru various barrel lengths? By the inch doesnt have a 5.7 section last i checked. I also want to see the long term durability and reliability of the 5.7 mags

View Quote

Well, the FiveseveN pistol has a 5” barrel, so that information is available. The P90 is a little over 10” and that information is available. I went with the 8” over the 5” was because I wanted more velocity over the pistols that I already have, plus I wanted a bit more handguard length.

Posted: 3/20/2020 4:24:09 PM EDT

[#32]

Quote History

Quoted:

Well, the FiveseveN pistol has a 5” barrel, so that information is available. The P90 is a little over 10” and that information is available. I went with the 8” over the 5” was because I wanted more velocity over the pistols that I already have, plus I wanted a bit more handguard length.

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Quote History

Quoted:

Quoted:
I really want to build one of these 5.7 conversions, but using their bolt and barrel(a built upper is way to much anyway!). Along with wanting to try to make a side charger if possible. The main debate is should i try for super compact PDW and use a 5 inch barrel or average size SBR with the 8 inch barrel? Does anyone have an reliable numbers on 5.7x28 ammo thru various barrel lengths? By the inch doesnt have a 5.7 section last i checked. I also want to see the long term durability and reliability of the 5.7 mags

Well, the FiveseveN pistol has a 5” barrel, so that information is available. The P90 is a little over 10” and that information is available. I went with the 8” over the 5” was because I wanted more velocity over the pistols that I already have, plus I wanted a bit more handguard length.

I thought the FiveseveN pistol has a shorter barrel then that. Good to know. The short handguard does concern me, but if i plan on SBRing it like i hope it would have a vert grip anyway.

Posted: 4/8/2020 12:52:20 AM EDT

[#33]

Quote History

Quoted:

I thought the FiveseveN pistol has a shorter barrel then that. Good to know. The short handguard does concern me, but if i plan on SBRing it like i hope it would have a vert grip anyway.

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You could spend hours on my channel watching velocity videos of a lot of 5.7 ammo. Or the general conclusion is the 8" CMMG is very close to if not sometimes exceeding the velocities produced in the 10.4" PS90 SBR/ P90..

I haven't updated this spreadsheet online in about 2 yrs:

5.7 Velocity Spreadsheet

Here is the review I did when they did the first 5.7 upepr

CMMG MK57 Guard Pistol Review! Brand New 5.7x28mm Firearm!

https://www.youtube.com/watch?v=QH3y1xC0ugM

Posted: 5/12/2020 7:35:18 PM EDT

[#34]

I have owned the 8" version for a little over a year. It was purchased as the full factory pistol that uses the FN pistol mags. It was the cheapest model, but I replaced most items on it since then.

I shot it very little and even played around with reloading.

I had a fiveseven pistol at the time too, and the FN pistol was a bigger pain to reload. For the CMMG it had been a breeze.

I just recently bought a 5" CMMG barrel and bolt in 5.7 to built my own "Banshee" style gun with my favorite uppers/lowers...Aero Precision.

The new 40rd mags seem to work very well so far. Only had it a few days, but the 50ish rounds fired ran perfect with LRBHO.

The mags do not drop free, but they fall about 3/8"...hoping they loosen up a bit more with use.

I think I will keep both guns, and make the 8" that uses FN mags into a mini scoped sniper. Just because:) If it isn't overall accurate, it will be sold.

The 8" doesn't make as much sense in my mind when you can build a 5.56 or .300 (have both).

The 5" makes the most sense to me, because it is lighter then 9mm loaded and the 5.56 in 5" is basically just burning most of the powder once it leaves the barrel.

Keep the little 5" as my go to PCP.

I plan to shoot it a bunch more this week.

I will report back.

I also just built another 9mm CMMG RDB. Did one before, but for whatever reason it didn't impress me. This new one (also only test fired) felt way better as far as recoil them the earlier build. I am sure it was all in my head, but whatever:)