Doing an AR platform PDW.  Lower is complete,  nothing has been purchased for an upper yet.  Form is approved, tax stamp is in the safe with my other vital documents.

Inspiration:  Barnes Precision PDW with MVB Industries ARC-X stock.



My complete lower is pretty much just what you see here.  Got the ARC-X stock.

I like the Barnes PDW, a lot, but I want to make a few changes to suit my desires.  That's why I didn't just buy that.

I want it to be as short and handy as is practical, and suppressed as well,  while maintaining enough muzzle energy to ensure that it'll get the job done should the shit really hit the fan and I have to use a personal defensive weapon for personal defense.

NOTHING has been selected yet for the upper.   So that's a blank page.  Please make recommendations keeping the basic idea in mind:

Effective as a PDW.
As short as practical.
Suppressed.  Suppressor may be able to fit under selected handguards.  I understand that if this is the case, then the suppressor may have to be attached at all times when firing, as gas pressure from muzzle blast can shred a handguard.

I already have one suppressor, an Allen Engineering AEM5 (same as Ops Inc 12th model) on my Mk12 Mod1 clone.   I'm favorably inclined to get another Allen suppressor which dictates  that the barrel length in front of the gas port be long enough for its collar and brake system.   Allen suppressors have an OD of 1.5 inches nominal.  So to shroud the suppressor, the ID of the handguard has to be over 1.5" OR I can abandon the idea of recessing the suppressor.  I would probably opt for the AEM2 or AEM3 suppressor.

A rail system on the top surface of the handguard or free float tube (either is possible at this point)  is desired. It can be optional or attachable as needed via keymod or mlok systems.

I have not yet even chosen the caliber for the upper.

Please feel free to make recommendations.    Barrel, caliber, length, twist, rail system, etc.

Been a while since I did my sbr.  I thought part of the form was specifying the caliber.   Did that change?

I really like 300blk for the ability to do supers and subs effectively.

I just rebuilt one of my SBR lowers into a 6in 300blk with a 5.5in SLR rail gibbz side charger upper, and a short troy tomahawk stock. It is bad ass and very small. I have not shot it yet, so I am not sure if the 6in barrel, and pdw stock with a proprietary buffer will all play nice together, if they do, I am still not sure how it will run with supers, subs, suppressed, unsuppressed, ect. I'm sure I can get it running either way. I did not build this with the intent of it always being suppressed as I wanted to build something about the size of my mp5k, but in a rifle caliber. I have it set up to share my sdn6 for right now.

I have another 300blk sbr with an 8in barrel and a form one reflex can that lives on the sbr all the time. The can is tucked under a Seeking keymod handguard. I like this set up a lot, but it is about the same length as an 11.5 ar with a fh, that's why I built this other one so small.

If you are going to tuck the can under the rail I recommend the Seeking rail, but there are others that will be a little skinnier and a closer fit to the can. If you are building a pdw I think you might want the option to make it a short as possible so being able to remove the can might be a plus.

James

Build whatever is on your stamp for length and caliber first.

Ok, thought maybe the opened it up a bit.  Then in that case build whatever is on the form 1 first and have the configuration on hand, and then 2nd vote would still be a short 300BLK.   That 9mm could be really cool too.

It'll start out as a .30 caliber build because that's what I put on the form.    I had momentarily forgotten that this information has to be there.

It's no big deal if I temporarily swap calibers later, but since I put .30 on the form I guess I'm going to pick a .30 caliber option to start with.

So...suppressed, super compact, and in .30 or .300 something.    I confess I'm not at all clear on the practical or technical differences between .300 Blackout and .300 Whisper.

In the red is what I plan on doing.

Get yourself a "Q" 7in 300blk barrel and make your own honey badger type AR.

The Sig Rattler performs quite well with a 5.5" Barrel, so I see no reason why an AR should perform any worse. I also like having something I can stash just about anywhere. Just be aware that the 5" SLR/Veritas barrels and the 4.75" KAK barrel have a 1:8 twist and don't stabalize subs very well...if that is important to you. KAK's 6.25" Barrel has 1:7.

Go short!
Attached File

I appreciate the Q barrel/honey badger suggestion but it doesn't fit with the non-negotiable requirement to accept an Ops Inc/Allen Engineering brake and collar setup for a future AEM2 or AEM3 suppressor.

I'm also thinking that I want to try out this build with a side charging handle.   I have always accepted the rear charging system of the AR platform but always have thought of it as a unique quirk of the design,  and not the most ergonomically correct solution.    I have tried side chargers and they feel like a natural and ergonomically correct solution to me.

Left side charging is ergonomically ideal when at the ready position. Right side charging requires changing holding hands but is also acceptable.

Ideally I'd like to find a non recip left side charger.

G4 upper is what you seek https://gibbzarms.com/product/g4-side-charging-upper-receiver-right-handed/

They have a left handed version that I'd prefer.  It's on the list of contenders but in truth I want a more "mil spec" cosmetic look to the upper.  I'm not a fan of fancy sculptured receivers, done just to make a given brand have a distinctive look.   I'm ultra conservative about such things.

But of course I'd get used to it soon enough.   The appearance isn't likely to be a deal breaker.

When it comes to firearms, the designs I prefer are all business and nothing fancy about them.

The left/right is for ejection, not charging. Right handed has ejection port on the right side the handle on the left side.
They have this one as well: https://gibbzarms.com/product/mg4-side-charging-upper-receiver/ Billet, but still with the dust cover and forward assist.

The one I can think of that's closest to mil-spec in appearance is made by Matrix Arms. I don't even know if they make them anymore. Middle one in the pic.

Attached File

The KAK value line 4.75" is 1/8, the stainless is 1/7.  I just got the stainless a few weeks ago.  Haven't had a chance to build it yet.

They don't.  They were infringing on Gibbz's patent.

7.5" 300BO, pistol length gas. Long tube if you're going to leave the can on, short if you're not. That's what I did and even without the PDW stock mine, complete with flash can place holder is about 23.99". probably getting a LWRC short stock since I want it lighter weight than PDW. Shoots supers and subs just fine, fits in a small bag. It's pretty much MP5 sized with a rifle round. My own version of the Honey Badger.

this pic shows just how short it will be. 870 is cropped to look like it will when my SBS stamp gets here and it's a 12" barrel.

My first SBR is on a Spike's lower marker "MULTI" already registered by Spike's.  The Form 4 went through as "MULTI".

I don't believe that flies anymore.

Hasn't been kosher for probably a decade or so.

8.5" CMMG 300BO is about the lightest 'in stock' barrel in a full performance length.  With a direct thread Omega 9k it's shorter than my 11.5" 556 with trifecta FH.  Side cockers are nice with an adjustable gas block shut off for sub sonics.  Turns it into a very quiet straight pull bolt action.

Shorter barrels are fine for subsonics external ballistics but start to lose energy on supers.  Even with pistol gas shorter barrels get finicky.  An 8.5" .300BO super has the same energy as a 14.5" M4 muzzle to 450 yds with 110gn bullets and the Vortex blacktip expands out to 300+ yards.