CMT Tactical UHP15PDW

[GOST]

https://www.cmttac.com/image/cache/data/STKL5493-2-800x800.jpg

CMT Tactical PDW Lower Receiver
UHP15PDW INTEGRATED LOWER SYSTEM

The UHP15PDW Lower receiver features the Integration of a Patent Pending Monolithic adjustable PDW type stock system. This Patent Pending Monolithic stock/lowwer receiver design is the result of a collaboration between BattleArms Development & Cross Machine Tool. The UHP15PDW lower also includes the Ambi Bolt release & Ambi Mag Release Lever similiar to the UHP15A lower receiver. The Ambi Mag release Lever is designed to work in conjunction with the Standard Mil-Spec Mag catch arm without the requirement of proprietary components for proper function. This mag release lever design provides the user field repair options of the mag catch typically not found with most ambi mag release systems that utilize proprietary mag catch arms. The Ambi Mag Release features a raised fence on 3 sides to protect the mag release from accidental actuation during weapon use. The Bolt release Lever & Mag Release Lever feature aggressive Texturing to ensure proper finger placement & grip during actuation. The ambi bolt release, ambi mag release & buttstock adjustment rods are Black Nitrided for corrosion protection.

The UHP15PDW is also available with engraving to start your personalized Rifle build. You may choose from one of the standard engraving options or have us laser engrave your SBR or Trust information on the receiver. SBR or Trust information is engraved to the .003 depth required by the ATF. SBR or Trust information can be engraved on the bottom of the trigger guard or on the right side of the receiver above the trigger pin hole. When selecting the SBR engraving option please specify desired Text & Location desired for the text to be engraved in the Notes area when placing your order. If you select the "Custom Engraving" option, please send your Black & White Logo to sales@cmttac.com & reference your order# when sending your graphic in a png, jpg or tif format.

PLEASE HAVE YOUR LOCAL FFL EMAIL THEIR FFL INFO TO FFL@CMTTAC.COM PLEASE ADD YOUR ORDER NUMBER AND NAME ON THE FFL.

Specifications

5 AXIS CNC MACHINED FROM 7075 T6 BILLET
TYPE III CLASS II ANODIZED BLACK
WIRE EDM MAG-WELL PROFILE
.154” DIAMETER REAMED TRIGGER & HAMMER PIN HOLES
MULTI CAL MARKED
INTEGRALLY MACHINED TRIGGER GUARD
3.3oz TUNGSTEN WEIGHTED BUFFER W/SPRING
INDUSTRIES SMOOTHEST WIRE EDM CUT FLARED MAGWELL, COMPATIBLE WITH USGI AND MAGPUL GEN 2/3 MAGAZINES
NO ROLL PINS NEEDED FOR ASSEMBLY
UPPER TENSIONING SCREW
BOLT CATCH ASSEMBLY SCREW
LIFETIME WARRANTY AGAINST MANUFACTURE DEFECTS
AMBI BOLT RELEASE/ HARDWARE
AMBI MAG ARM RELEASE LEVER
PATENENT PENDING INTEGRATED 4 POSITION STOCK WITH 4 INCHES OF PULL
PATENT PENDING PDW STOCK CHEEK WELD
PATENT PENDING PDW INTEGRATED STOCK LINEAR GUIDANCE SYSTEM
PATENT PENDING STOCK BALL LOCK MECHANISM
COMPATIBLE WITH STANDARD LOWER PARTS KITS
WEIGHT COMPLETLY ASSEMBLED- 2LBS 4OZ. ( wt. includes standard LPK & grip not included with the UHP15PDW)

https://www.cmttac.com/image/cache/data/STKL5481-2-800x800.jpg
https://www.cmttac.com/image/cache/data/STKL5486-2-800x800.jpg

MSRP $659.00

https://www.cmttac.com/PDW-STOCK-

[UWone77]

I told Jeff Cross to pre engrave mine to Form 1.

[GOST]

I wish I hadn't already had other projects started, cause that's straight up sexy.

[Dstrbdmedic167]

Ohh nice! Now this is something I can use lol. With trust info and my logo engraved. Yessir! Good call on pre-engraving.


I wish I hadn't already had other projects started, cause that's straight up sexy.

Agreed. Sexy enough for me to abandon my umbrella build!

[alamo5000]

I told Jeff Cross to pre engrave mine to Form 1.

A little off topic... but when you Form 1 a lower for an SBR it must be engraved with the trust name (because putting those two pins in makes you the 'manufacturer')...correct?

Is there any specific guidance or location or anything like that where said engraving must take place? Or can you engrave it where ever it fits? Does it have to be a certain size or in a conspicuous place? What's the rules?

[UWone77]

A little off topic... but when you Form 1 a lower for an SBR it must be engraved with the trust name (because putting those two pins in makes you the 'manufacturer')...correct?

Is there any specific guidance or location or anything like that where said engraving must take place? Or can you engrave it where ever it fits? Does it have to be a certain size or in a conspicuous place? What's the rules?

ATF 5300.4 in 27 CFR 479.102 (page 92) describes what is necessary to engrave on a SBR or SBS when one is manufacturing. This is not necessary if you purchase one that is already manufactured as it will have been done for you.

1) On the Frame or Receiver the Serial number;

2) on the frame, receiver, or barrel the following additional information;

A)The model;

B)The caliber or gage;

C)Your name or name of the Trust in the case of a Trust (no abbreviations are permitted for the Trust name);

D)The city and state (you can abbreviate the state with the official 2 digit state code)

The above mentioned information must be engraved, casted, stamped (impressing) or otherwise conspicuously placed or caused to be engraved, cast, stamped (impressed) or placed to a minimum depth of .003 inch and in a print size of the Serial number shall be no smaller than 1/16 inch.

[Aragorn]

How's THAT for timing... Sheesh. It's like they KNOW!

[alamo5000]

B)The caliber or gage;



So what happens if I SBR a lower and I put a 12.5" 5.56 on there and later decide I want a .300 BO upper as well?

[GOST]

I'm betting that these will be damn hard to get.

[GOST]

So what happens if I SBR a lower and I put a 12.5" 5.56 on there and later decide I want a .300 BO upper as well?

You can change out uppers, you just have to be able to change it back to original configuration.

[alamo5000]

You can change out uppers, you just have to be able to change it back to original configuration.

I've heard that before... but my lower is engraved 'multi cal'... I wonder if that would do? Or do you have to be exact?

[GOST]

I told Jeff Cross to pre engrave mine to Form 1.
You need to ask Jeff if there is a poor moderator from TN discount?

[GOST]

I've heard that before... but my lower is engraved 'multi cal'... I wonder if that would do? Or do you have to be exact?
You will have to engrave the caliber you specify on your form 1.

[alamo5000]

I wonder how much it would cost me to have CMT engrave it for me?

Not that I am doing it. Yet.

Yeah, right. Never mind. I wonder how much it would cost me?

Also my trust name and my city and state name both have the same exact number of letters in it :)

I wonder if they could engrave '5.56' on a CMT lower instead of 'multi cal'.... so many questions...

[UWone77]

I wonder how much it would cost me to have CMT engrave it for me?

Not that I am doing it. Yet.

Yeah, right. Never mind. I wonder how much it would cost me?

Also my trust name and my city and state name both have the same exact number of letters in it :)

I wonder if they could engrave '5.56' on a CMT lower instead of 'multi cal'.... so many questions...

I think they charge $60 or so for engraving. They have a 50K machine, it's slices, dices, and cuts very clean.

[GOST]

SBR engraving is additional $30.00 at CMT, which is a great deal. Custom engraving is additional $50.00. I would email or call them and see what they can do.

https://www.cmttac.com/index.php?route=information/contact

[alamo5000]

I think they charge $60 or so for engraving. They have a 50K machine, it's slices, dices, and cuts very clean.

So the lower plus $200 bucks plus $60 for my own custom engraving....I am just trying to think of all the stuff I would be into it for...if I pre-engrave that sucker then form 1 it....I would have one clean looking SBR lower :)

If I do an SBR odds are it will be CMT.... and odds are I will have a dedicated lower for just that. So basically I have to allot for building an entirely new rifle to do it the way I would like.

[alamo5000]

"The GEN2 UHP-15 Lower receiver with engraving is the perfect way to start your personalized Rifle build. You may choose from one of the standard engraving options or have us laser engrave your SBR or Trust information on the receiver. SBR or Trust information is engraved to the .003 depth required by the ATF. SBR or Trust information can be engraved on the bottom of the trigger guard or on the right side of the receiver above the trigger pin hole. When selecting the SBR engraving option please specify desired Text & Location desired for the text to be engraved in the Notes area when placing your order."

I might drop them an email and see if they have a sample pic of each location so I could choose wisely before I buy.

[UWone77]

I've got mine engraved on the bottom of the trigger well. Clean, and not noticeable.

[alamo5000]

I've got mine engraved on the bottom of the trigger well. Clean, and not noticeable.

Are you talking about where you put your trigger finger on the inside or on the bottom of the trigger guard area? I am open for all kinds of suggestions.

If I am going to own this thing for the next 50 years I don't want it looking like crap :) I have some ideas but I am not sure if they can or would do that. Also I am not really familiar with laser engraving. Is that supposed to be better or worse? I assume my current lower... the Gen2 UHP15 has all standard engraving on it....Personally I am a minimalist on things of that nature.

In your above post it said I would have to specify the caliber in the engraving...so 'multi cal' where it is now won't work?

Eh I just need to see some and how they are done. I just want it to look professional.

[bzdog]

You will have to engrave the caliber you specify on your form 1.

I thought it was acceptable for that the caliber to be engraved/stamped on the barrel, and most are marked as such already.

-john




2) on the frame, receiver, or barrel the following additional information;
[...]

B)The caliber or gage;

[GOST]

I thought it was acceptable for that the caliber to be engraved/stamped on the barrel, and most are marked as such already.

-john


Sent from my iPad using Tapatalk
You may be correct, someone with better knowledge will have to weigh in.

[SINNER]

Are they doing any type of preorder or just the email when in stock routine? I do not want to miss out on at least one of these.

[voodoo_man]

Fuuuuu. Wanttttt

Does cmt do LE discounts?

Lol

[gatordev]

I thought it was acceptable for that the caliber to be engraved/stamped on the barrel, and most are marked as such already.

-john

Correct. You don't have to engrave caliber on the receiver if it's already stamped somewhere else. Technically, you could engrave everything on the barrel and be "legal," but then the receiver would be married to the upper for the AR platform, which is obviously not as convenient.

[Slippers]

Edited: gator beat me to it.

I would like to stress that if you put "multi caliber" on your form 1, the ATF will reject it.

[UWone77]

For those interested in the CMT PDW Lower, looks like Rainier Arms will have the first 60 units for sale. They'll be available for preorders sometime today, at a slightly discounted rate of $625 I believe.

[titanse05]

Serious question here....other than it looks good, what reason do I need this lower?

[UWone77]

Serious question here....other than it looks good, what reason do I need this lower?

You don't, unless you want the PDW type stock built into the lower.

I would personally only run it if you were going to SBR it as well.

Price point, stock, SBR factor, definitely not for everyone.

[titanse05]

You don't, unless you want the PDW type stock built into the lower.

I would personally only run it if you were going to SBR it as well.

Price point, stock, SBR factor, definitely not for everyone.That's what I figured just needed to make sure. [:D]

How does one remove the takedown pin on this setup?

[SINNER]

How does one remove the takedown pin on this setup?

Fully extend the stock.

[gatordev]

You don't, unless you want the PDW type stock built into the lower.

I would personally only run it if you were going to SBR it as well.

Price point, stock, SBR factor, definitely not for everyone.

I had the same question, but I was trying to figure out how (other than looks) this would be different than running a reduced LOP stock (like a Fiberlite CAR stock) on a normal lower and just leave it fully collapsed. It's hard to tell in the pic, but it seems like it's a very similar LOP, just unique and MP5-looking.

[SwissyJim]

dammit. And I'm expecting my 2nd SBR stamp to be back anyday. Damn my lack of patience!! If I'd only waited.

Soooo... think it'd handle 458Socom use? [BD]

[GOST]

Soooo... think it'd handle 458Socom use? [BD]

Only one way to find out.[BD]

[SwissyJim]

Only one way to find out.[BD]

Aw man I wish. But I JUST mailed off my $200 check for the Salvo12 can, not to mention the cost of the can itself. And some upcoming vet bills...:(

I just could not come close to justifying it. Someday down the road, maybe... for now, the 458S will just have to get swapped onto one of the other SBR lowers.

[GOST]

I think a version of this lower/stock made for a SCAR would be awesome, especially considering that it wouldn't need to be serial numbered. Rainier Arms/CMT SCAR PDW Lower has a good ring to it.

[SINNER]

That would be quite an undertaking. The lower on a scar engages the stock to lock it on. It also captures the recoil spring when the stock is slid on. Lots of proprietary parts to make it happen.

[GOST]

Didn't say it would be easy, but since Handl Defense has already made an aftermarket lower and FN has a PDW SCAR I figured it would be possible. Just thought it may be a decent idea since the SCAR aftermarket isn't saturated yet.

http://www.fnhusa.com/files/9713/6855/6216/scar_family_pdw_large.png

[UWone77]

Didn't say it would be easy, but since Handl Defense has already made an aftermarket lower and FN has a PDW SCAR I figured it would be possible. Just thought it may be a decent idea since the SCAR aftermarket isn't saturated yet.

http://www.fnhusa.com/files/9713/6855/6216/scar_family_pdw_large.png

I'm guessing the aftermarket parts market for SCAR's aren't saturated because there are very few SCAR owners compared to AR's or even AK's.

I'll still take a 10.5 SCAR with the stock folder.

[Aragorn]

I'm guessing the aftermarket parts market for SCAR's aren't saturated because there are very few SCAR owners...

That, and that backwards. I didn't buy a SCAR a few years ago because there wasn't an aftermarket for it like there was AR's.

[GOST]

SCAR is slowly growing, it may be time to get in on the ground floor before there is much competition.

[Dstrbdmedic167]

You know the gears have really been turning and I'm think hard that I may go with one of these over the umbrella billet. 😱😱

[Aragorn]

You know the gears have really been turning and I'm think hard that I may go with one of these over the umbrella billet. 😱😱

��

So what are you going to do with the billet Umbrella? Seems like their readily available anymore...

And yours is so pretty.

[Dstrbdmedic167]

í*½í¸±

So what are you going to do with the billet Umbrella? Seems like their readily available anymore...

And yours is so pretty.

I'd sell it if I really went this route. It's very tempting...

[GOST]

Look what just went live.

Rainier Arms Exclusive! We just confirmed our shipment from Cross Machine Tool and we'll be getting the first shipment of their new Integrated UHP15 PDW Integrated Lowers! These are smoking hot and we have a special Pre-sale on these! Shipping these out June 23rd.

http://www.rainierarms.com/uhp15pdw-integrated-lower-system

[UWone77]

Updated Specifications:


https://www.cmttac.com/PDW-STOCK-


5 AXIS CNC MACHINED FROM 7075 T6 BILLET
TYPE III CLASS II ANODIZED BLACK
WIRE EDM MAG-WELL PROFILE
.154” DIAMETER REAMED TRIGGER & HAMMER PIN HOLES
MULTI CAL MARKED
INTEGRALLY MACHINED TRIGGER GUARD
3.3oz TUNGSTEN WEIGHTED BUFFER W/SPRING
INDUSTRIES SMOOTHEST WIRE EDM CUT FLARED MAGWELL, COMPATIBLE WITH USGI AND MAGPUL GEN 2/3 MAGAZINES
NO ROLL PINS NEEDED FOR ASSEMBLY
UPPER TENSIONING SCREW
BOLT CATCH ASSEMBLY SCREW
LIFETIME WARRANTY AGAINST MANUFACTURE DEFECTS
AMBI BOLT RELEASE/ HARDWARE
AMBI MAG ARM RELEASE LEVER
PATENT PENDING INTEGRATED 4 POSITION STOCK WITH 4.125" INCHES OF EXTENSION
PATENT PENDING PDW STOCK CHEEK WELD
PATENT PENDING PDW INTEGRATED STOCK ROD LINEAR BUSHING GUIDANCE SYSTEM
PATENT PENDING STOCK BALL LOCK MECHANISM
COMPATIBLE WITH STANDARD LOWER PARTS KITS
WEIGHT COMPLETELY ASSEMBLED- 2LBS 4OZ. ( wt. includes standard LPK & grip not included with the UHP15PDW)
INTEGRATED STOCK IS 1.75" SHORTER (LOP) THAN A STANDARD MILSPEC CARBINE STOCK WHEN IN THE COLLAPSED POSITION.

[SINNER]

Is it even possible to do the engraving through Rainier or only with a direct CMT order?

[jdhill]

Is it even possible to do the engraving through Rainier or only with a direct CMT order?

^^This^^

And, is there a QD socket on the stock? The picture kinda looks like it, but no mention in the specs...

Another question... regarding the "INTEGRATED STOCK IS 1.75" SHORTER (LOP) THAN A STANDARD MILSPEC CARBINE STOCK WHEN IN THE COLLAPSED POSITION." How does that compare to the NEA or MVB offerings?

[UWone77]

Is it even possible to do the engraving through Rainier or only with a direct CMT order?

Probably easier just going with a direct order from CMT, so it ships directly to your FFL, instead of having it engraved, then shipped to Rainier, then Rainier shipping it to your FFL.

[SINNER]

Just going to do the engraving after I receive it then. Since my FFL charges me a single transfer fee for up to 5 firearms I feel that to be thrifty I should max out the transfer every time. LOL

[Txfilmmaker]

Man! That looks very cool!

[SINNER]

Got a tracking number today but I am not sure if they shipped some other lowers I ordered without it or the CMT went out also.


I did talk to Sony today at Rainier to verify My FFL and she was awesome to deal with. Credit where it's due, Rainier has been flawless the past 5-6 orders.

[GOST]

Looking forward to seeing what you end up putting together Sinner.

[UWone77]

Got a tracking number today but I am not sure if they shipped some other lowers I ordered without it or the CMT went out also.


I did talk to Sony today at Rainier to verify My FFL and she was awesome to deal with. Credit where it's due, Rainier has been flawless the past 5-6 orders.

Sony is good peeps.

Got my order into CMT. Should see mine next Tuesday. I have no idea what to do with it yet since Form 1 SBR's are on hold for my state. I might just submit it anyway.

[GOST]

Sony is good peeps.

Got my order into CMT. Should see mine next Tuesday. I have no idea what to do with it yet since Form 1 SBR's are on hold for my state. I might just submit it anyway.

You should have some custom engraving done to that big blank space. I know some dude that may draw something up for you.

[SINNER]

Looking forward to seeing what you end up putting together Sinner.

I have no idea what it will wind up being at this point. I already have more Blackout's and 6.8's then I will ever use. Lol maybe another .458.


Sony is good peeps.

Got my order into CMT. Should see mine next Tuesday. I have no idea what to do with it yet since Form 1 SBR's are on hold for my state. I might just submit it anyway.

That sucks about the form 1 bullshit you all are dealing with. I think I read it right that you just can't build it yourself? Have Rainier "build it" for you. You seem to be there all the time anyway. Hahahaha

[GOST]

https://fbcdn-photos-e-a.akamaihd.net/hphotos-ak-xpf1/v/t1.0-0/10984837_1003358886350368_674036007297100533_n.jpg ?efg=eyJpIjoidCJ9&oh=3e1718c3cdf344e5fecf47aafc81fa4d&oe=56344A20&__gda__=1445955402_7f566b9a427dde41c94bd9a95557629 6

From CMT's Facebook page:
One of the unique Patent Pending features found on the UHP15PDW Lower is the use of Composite Linear Bushings guiding the stock rods that can be seen in this photo inside the stock rod housing. This provides a non-galling, smooth movement of the stock with NO metal to metal contact around the Nitride coated S7 tool steel stock rods except for on the stock position lock detents. The composite bushings are the same type bushings that are used with Industrial Linear Motion actuators. The presence of the composite bushings provide a longer durable service life of the system versus just a alloy steel rod thru an anodized aluminum hole.

[UWone77]

I have no idea what it will wind up being at this point. I already have more Blackout's and 6.8's then I will ever use. Lol maybe another .458.



That sucks about the form 1 bullshit you all are dealing with. I think I read it right that you just can't build it yourself? Have Rainier "build it" for you. You seem to be there all the time anyway. Hahahaha

Once a week... mainly to have lunch with the guys. [:D]

[UWone77]

Looks like Stick has all the available colors to replace the cheek weld


http://i849.photobucket.com/albums/ab55/UWone77/Stick_zpsny15mnul.jpg (http://s849.photobucket.com/user/UWone77/media/Stick_zpsny15mnul.jpg.html)

[Dstrbdmedic167]

Nice! Wonder if solid colors would ever be available?

[UWone77]

Picked mine up today. Nice doesn't even begin to describe it.

[SINNER]

Good to hear. Looking forward to building this one up.

[UWone77]

Good to hear. Looking forward to building this one up.

The CMT cigar was also a nice touch.

[GOST]

Picked mine up today. Nice doesn't even begin to describe it.
Rub it in.

[Dstrbdmedic167]

Not...even...cool... want so bad!!

[Txfilmmaker]

Pretty sweet!


Sent from my iPhone using Tapatalk

[UWone77]

http://i1016.photobucket.com/albums/af282/richdkim77/IMG_3474_zpsguxfkyqs.jpg (http://s1016.photobucket.com/user/richdkim77/media/IMG_3474_zpsguxfkyqs.jpg.html)

[toolboxluis00200]

I need to stop looking at this thred . :(

[UWone77]

I need to stop looking at this thred . :(

Yes you do!


http://i1016.photobucket.com/albums/af282/richdkim77/IMG_3475_zpsh3ujcqop.jpg (http://s1016.photobucket.com/user/richdkim77/media/IMG_3475_zpsh3ujcqop.jpg.html)

[toolboxluis00200]

I saw that on FB already lol. [BD]

[SINNER]

The CMT cigar was also a nice touch.

They all come with a cigar or is it just for the special people? lol

[GOST]

They all come with a cigar or is it just for the special people? lol

I believe that CMT includes them with all their lowers.

[GOST]

Yes you do!


http://i1016.photobucket.com/albums/af282/richdkim77/IMG_3475_zpsh3ujcqop.jpg (http://s1016.photobucket.com/user/richdkim77/media/IMG_3475_zpsh3ujcqop.jpg.html)

This is gonna be sexy. A Mega Wedge Lock would be a great addition to this.

[UWone77]

http://i1016.photobucket.com/albums/af282/richdkim77/IMG_3490_zpsmfesrqxl.jpg (http://s1016.photobucket.com/user/richdkim77/media/IMG_3490_zpsmfesrqxl.jpg.html)

[Dstrbdmedic167]

Well you didn't waste any time. What type upper setup are you gonna run?

[toolboxluis00200]

Just for fun u need to slap a 7.5 upper on it

[UWone77]

http://i1016.photobucket.com/albums/af282/richdkim77/IMG_3509_zps1caqdtby.jpg (http://s1016.photobucket.com/user/richdkim77/media/IMG_3509_zps1caqdtby.jpg.html)

[mustangfreek]

Damn....:P

[Cotton68spc]

Awesome how do you like the PDW


Check me out on YouTube and Facebook

[UWone77]

Awesome how do you like the PDW


Check me out on YouTube and Facebook

Not enough time with it yet. It definitely begs to be SBR'ed at some point as it doesn't seem right with a longer 14.5 or 16" upper.

[GOST]

Now available in FDE and coyote.

http://www.rainierarms.com/cmt-uhp15pdw-integrated-lower-system-fde

http://www.rainierarms.com/cmt-uhp15pdw-integrated-lower-system-coyote

[Dstrbdmedic167]

Mmmm... FDE...

[alamo5000]

http://i1016.photobucket.com/albums/af282/richdkim77/IMG_3509_zps1caqdtby.jpg (http://s1016.photobucket.com/user/richdkim77/media/IMG_3509_zps1caqdtby.jpg.html)

Sexytime.

[Txfilmmaker]

Nice!


Sent from my iPhone using Tapatalk

[Cotton68spc]

I need a pdw sbr but my wallet says no LOL


Check me out on YouTube and Facebook

[schambers]

does that use a carbine length buffer tube?

[UWone77]

does that use a carbine length buffer tube?

I believe it's shorter.

[SINNER]

1.5" shorter.

[UWone77]

1.5" shorter.

Thanks buddy, I was going to say 1.5" but couldn't recall exactly what I was told.

[SINNER]

Anytime I can pretend to be helpful. lol That looks really good with the lefty upper and the Fortis.

[LCSO264]

1.5" shorter.

So, with a shorter buffer tube, does this use a modified carrier group or something?

[UWone77]

So, with a shorter buffer tube, does this use a modified carrier group or something?

Standard BCG.

[LCSO264]

has anyone tried a 416/MR556 upper on these? with the tube being shorter, I'm curious if the piston uppers will run reliably?

[GOST]

has anyone tried a 416/MR556 upper on these? with the tube being shorter, I'm curious if the piston uppers will run reliably?

I've not seen one with a piston upper. I would email either CMT or BAD and ask.