I really like my RDB, and really-really like the development prospects I think the gun has.  The way the receiver is set up, I think this gun could one day be the most modular and open-source design yet.

So let's document the available aftermarket stuff out there now, and pitch our best ideas for improvements or modifications!

Earlier thread on the same topic, now archived, with a bunch of other good ideas

Kel Tec Offerings;
-They built a brass catcher but haven't marketed it (dumb)
-They have short & long handguards out there for the RDB-S and RDB-C models (partial availability from OEM)
-They have a flared magwell thing that I'm told is awesome but don't personally understand the need for
-The RDB-S has a sort of length adjustment capability in that the stock mount can slide on the takedown pins a short ways

Aftermarket Offerings;
-So far I'm aware of the MLOK handguard from Lucky Irishman
-And that's about it

Here's the Potato Handguard.  Not my personal cup of tea because of the length, but a very strong first showing for aftermarket support;


Places where improvement is most needed;
-Better detent for gas regulator (personally, I think a forward-venting setup would be nicer, too)
-Alternate options for handguards, pistol grips/frames, and cheek rests
-Full function cheek rest, with an indexing surface or texture for your gob, and some degree of height adjustment (though not much is needed, really)
-A sliding plate or door on the receiver that gives visual or finger access to the chamber from the top side (the biggest beef RO squares have with the gun's layout)
-More modular frame that has removable pistol grip & trigger guard.  Maybe a drop in trigger group that interfaces with the OEM hammer & struts, maybe swappable magwell inserts
-Heat-shielded takedown pins in the foregrip
-Adjustable trigger overtravel/etc
-Metal mag compatible mag catch with more inward travel and a stiffer spring (or more 'clicky' travel out of the locked position)
-QD sling sockets in at least some of the many, many screw holes, and fewer assorted loops for hook-slings sticking out
-Battery/etc storage dealie that snaps into the pistol grip, or a door/plug at least
-Combination brass catcher and ejection-port dust cover
-Chamfers on all takedown pin holes, and polished, hardened, nitrided takedown pins.  Capture detents on both sides of the frame, but only one detent groove at the end of the pin-
-Buttpad options (current is Spartan and the rubber pad slides off too easily)

What the Aftermarket Needs;
-80% receiver flats; this thing is simpler to build than an AK
-Stripped barrel trunnions and gas blocks --this is how you get a following of aftermarket gun-builders, Kel-Tec
-Complete bolt heads, or even better, carrier groups --this is how you get a bunch of caliber conversions and aftermarket demand without paying for R&D
-Interface specs for takedown pin holes, and where the pinned sections have to fit together or inside each other --that's not giving away the keys to the kingdom, this is how you get many businesses producing quality products to supplement your own, increasing the baseline demand

Let's break up some of this text with a photo of @Dustyattic's slightly-modified RDB, which is probably the closest thing I've seen to my own vision of a properly configured RDB so far;


Speculative/Wishlist;
-A much heavier steel optics rail, to rigidly clamp the front & rear of the barrel, paired with a heavy steel picatinny lower rail with a turnbuckle tension adjustment
-Lighter-weight optics rail for those of use of us using a short low-power prism optic or red dot (which seems to be most)
-Short monopod, maybe folding bipod, that collapses into the pistol grip, and can raise the gun just high enough to accommodate a 30rnd PMAG while prone
-PDW variant; do what is necessary to reduce or eliminate the 5" distance between the barrel trunnion and the rear sight rail block (where the FCG sits), and chop the barrel close to the gas block for a suppressor mount.  Now that the distance between chamber and gas piston head is so much shorter (more like a standard rifle length), plumb a gas tube between a low-pro block near the chamber forward into the main gas block so the gun can run subsonic 300BO or 9x39.  Lastly, reconfigure the gas regulator such that it can be quickly toggled between the front or rear gas block ports for subsonic or supersonic use, with independent adjustment settings for each port.
-A licensing agreement for production by B&T.  Talk about something that would beat the pants off all competitors!

My latest idea is to put notches on the front of the rear optics rail/handguard trunnion, so the charging handle can be folded flat while the action is pulled back, and also prevent the bolt from dropping.  If accessing the part isn't a nightmare, I will likely just make a replacement since it's a pretty simple flat steel part.

(First a little background; when the cocking handle is unfolded, a small stud at the rear of the handle rotates into a notch on the op-rod, which 1) stops the handle rotation at 90degrees, and 2) acts as a quasi forward-assist so long as the handle is unfolded (you can force the bolt carrier home with it, despite the handle being non-reciprocating). When the cocking handle is fully withdrawn it runs into the rear sight rail support trunnion pinned to the barrel, which is basically a flat wall. At that point, the handle may be rotated up into a notch in the sight rail, where it is locked back like an HK charging handle. Super good.)

Okay, here's where the notch comes in; when the handle is fully locked back into the optics rail, it juts out way too far for the gun to be carried this way (you're begging for the handle to get caught and drop down). The stationary clevis portion of the handle hinge is what catches the optics rail, so the only thing stopping the handle from folding is that little tab interfering with the sight rail trunnion. A strategic notch on that sight rail trunnion would allow that cocking handle tab to rotate back down so the handle could be folded flat, and at the same time lock the bolt from being dropped until the handle it pulled up again.

It sounds like a useless feature, but I think it could actually be quite useful, especially in the competition circuit where this type of 'sealed' gun is so difficult to show clear at the end of a stage. With the handle locked back, there is a visual indication the gun is safe to move with, and with the handle folded, it won't get in the way between stages. The exposed skinny recoil spring guide under the optics rail is even easier to spot from all angles as an indication of safety.

And here's the other part; when, not if, someone finally gets a quality brass-catcher or ejection port cover designed for the RDB, this would allow for carry with a loaded magazine, with the bolt locked back (and ready to drop & chamber with a finger flick), safely and without exposing the action to dust or debris. I'm not aware of any other rifle that has such a capability. I suppose it could be useful for your over-the-beach HK types that need their barrels drained, lol.

Cushier buttpad perhaps?

Noted!  Any thoughts on better/different sling arrangements back there?  Maybe a tilt/cant adjustment for the pad, or an even tinier 'pdw' foot (or brace )?  I suppose the upper sling loop is fine, but I personally don't care for stuff sticking out of the rifle, so QD-sockets on either side further down would be my preference.

Why would KT cut their own throats on a cash cow by allowing this?  Receiver flats only make sense when the rest of the parts are dirt cheap, and if KT did offer a receiver flat, I'm sure the rest of the parts would come out to MSRP for the gun...

I agree NOTHING or QD sockets would be better than the loops that stick out. The recoil is so soft, I like the buttpad (a  bit smaller might be cool though).  I like the X95s Israeli size buttpad's top-to-bottom length.

I really do WANT that KT "tactical" rail.  IF they won't make it, they should give the design to someone else to make.  
I agree the S-handguard looks better, but I sure wish it had a flat mlok area at the front before the hand-stop curve. I just like VFGs on my guns (likely because I started with AUGs back in like 1990, when US Customs adopted them).

I DO wish the optic rail were a bit lower (someone made a lower and slightly longer one for the RFB for $99 I think). I really find that cowitness is a bit too high for me, but I can't find CASV or LARUE height mounts very easily. The primary arms cyclops looks like it might be a hair lower than cowitness...and, for me, 1.3-1.35" is the magic number.  
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Question:  IS the exposed op-rod a weak-point for torture testing, or is it mainly the open ejection port (where gunk can get up into the hammer and bolt-recoil area)?
 

So people could produce pistols & braces, m'boy!  Also, that stamped sheet metal probably has more cost in overhead than anything else on the gun; avoiding that while also increasing demand for the remaining parts is a win.  And it's not like KT couldn't supply the flats themselves and make even more money.

So maybe something like the S handguard, but with Mlok slots on the flat sides & bottom?  That seems like it could be done without too much trouble, maybe still using just polymer?

I'm not sure the optic rail can get much lower, at least not without dropping the top edge of the handguard as well so the cocking handle points downward (which I think would be a win for clearing optics, personally).  My Cyclops sits a hair high for me unless I do a 'tooth rest' vs 'cheek rest.'  It sure looks like there is room to drop the mount height at least another 1/4", so I suspect PA already makes something (I just haven't bothered to look for it yet).  Sadly, I think I'm going to go back to my 2.5X simply because I don't think my eyes are good enough to acquire targets 200+ yards away with only the 1X power, even if it's in focus.  Maybe with more practice in that area I can go back.  I think a better cheek rest may be a superior solution; the loud hammer alone kind of begs for a 3/8" foam/rubber pad of some sort.

The recoil spring guide should never see any real load outside of charging.   Maybe it's not a good idea to pull the handle off-axis while charging?  But pulling straight back will only apply torque, which is all carried by the much-stiffer op-rod tube.  I do think it suffers from being too high up relative to the optic mounts, same as with most other non-AR guns, to be honest.  Luckily, the Cyclops and 2.5X ACSS both get mounted right near the end of the optics rail for me so it's less of an issue.

I think a good sling arrangement needs to be 'finalized' for the RDB as well.  I know urban ERT makes an RDB-specific one, but man that thing looks over complicated.  Something between that and the crummy one KT included would be nice.

Also, does anyone actually use the bolt-release knobs?  If they were to the rear of the safety or something I could see using them, but they're nearly aft of the magwell .  With the charging handle latch (and perhaps my latch mod) it seems redundant and very disadvantaged.  The reason I bring it up, is that the external ribs on the lower frame appear to be more like 'fences' for the bolt latch controls and rear side sling swivels.  I think you could buff those all off and have a thinner and much flatter profile, to go with a slimmed down handguard.

I haven't seen a reasonable argument the ejection port presents any kind of issue at all.  It's narrow, it's deep...what are you doing that would cause debris to work its way in there?  Yes you can dump mud in it and try to shoot without clearing it out, but again, that's not reasonable.  I'm far more concerned about the hammer springs' longevity; tension springs suck hard, always.  The trigger/sear area is also very cramped & has more moving parts than usual, so it'd be really bad if gunk were to make its way into there.  The primary issue here is how much smaller the interior is than say an AK or AR, so it may be unavoidable and just a trade off for a smaller profile.

Again, why?  At the moment, they own the market in that product niche.  You can't put a brace on a bullpup, at least not without forcing ATF to officially re-examine the farce that braces already are.  Do you really want that?  Regarding the rest of the parts, it really would be a question of where they get them?  Are they produced in-house or via a third party?  If in-house, then to support home-built guns that could seriously negatively impact their company (It's an RDB...never worked and KT wouldn't do anything to help me...for the homebuilt gun...) they would have to increase production capability and given the market is so small to start, it would be a capital investment that would likely never pay for itself over the long-run.  If they get them from a third party, that makes things a little more flexible, but it still circles back to the original question:  Why would they undercut themselves?

If the design was in the public domain, like the AR or AK, that might be different, since there are numerous companies offering finished product.  But this is a unique product from one company and I just don't see them undercutting themselves or their dealers.

-- Yeah.  I guess aluminum has the advantage in cooling and strength (I once used layers of tin-foil inside a cheap AK foreend, and it definitely helped...I'm not above that).  I definitely think a flat area on the bottom front of the S-like handguard would be good--while I mount lights at 12, some prefer mounting at 6.  I just want a VFG if possible.

-- Yeah, it doesn't look like it'll go down much, BUT a charging handle that sticks out 15-20 degrees lower would help clear some optics (I have an RDS mounted all the way back--since the further back it is, the less the too-high height of the mount matters). But for those running WIDE optics like EOtechs and MEPROs, optics do get in the way of charging handles.

-- That doesn't kill your close-in (5Y to 25Y) speed?

--  I agree, but I haven't heard of a good solution yet.  Someone who tried this (with a SUB-2K) had the material separating after just 2-3 months of usage. I'm sure there IS something out there that would work, and it would serve multiple purposes (higher cheekweld, softer/absorbing, cooler to the touch when gun is sitting in sun--I'm in FL).

 -- I don't use a sling for HD, but I have an extra Frank Proctor sling--they're very simple, but good (I do wish they were a bit thicker in the width of the strap).

 -- They're similar to the position of the AUG bolt release, however, it's much harder to push down.  I was thinking of buying the irishman version (for like $40?).  However, I can't imagine they and the "fences" make the rear that much thicker.  I think a slightly shorter height buttpad might make it feel slimmer.

 --  Yeah, only when it's literally CAKED in mud, does it get up in there--which is not realistic for 99.99% of users.  Will mud in the op-rod area ALSO cause jams?

 -- I didn't realize this about tension springs. Glocks (at least until gen4) used a tension spring for the striker (and I only ever heard a few reports about it breaking), and I liked that there were two in the RDB (assuming that this increases longevity). The hammer is insane to look at, but then, I haven't really looked at the hammer inside the X95 to compare. I doubt we'll get geiselle helping us out with anything there, but does the design allow for a drop-in replacement pack like we see with the X95 and ARs...it kinda reminded me of a weird double hook AK when I looked at it.

Why wouldn't they want an aftermarket?  Is that your question?  I should think it obvious that a healthy aftermarket increases demand for the source platform.

1) License the design and they'd make tons of money for zero effort; they already can't satisfy market demand, and much of the market wants no part "becuz Kel Tec" anyhow.  I'm serious about B&T (or a similar quality company) being given a shot to make a deluxe version
2) Wild guess as someone in manufacturing; the parts production *probably* isn't the bottleneck, but instead assembly & packaging.  Producing a few flats for builders would be an inconsequential diversion, which is the REAL reason they might not want to bother
3) Is there any demonstrated liability --at all-- for the 80% builder market, for any of the manufacturers?  "Problem customers" are a problem no matter what product you sell, but have we seen recalls or lawsuits or reputations ruined because of 80% precursors?  This isn't a new phenomenon, it's been big for over a decade now; the only question is whether a company wants to bother with small potatoes that could be seen as a distraction
4) My impression is Kel Tec does most/all of their fabrication in-house; they are a good-sized machine shop after all, and one of the primary focuses of the RDB was to reduce fabrication costs.

My argument for why it's worth it to pay some attention to the small, home or custom builder market, when your design is brand spankin' new, is simply R&D.  R&D is expensive, and inherently speculative.  Lots of good ideas (M43 as a very bright and obvious example) go absolutely nowhere.  Public development is where the unpaid genius comes in, and reinvents the original product in new & exciting ways, and without costing a dime.  And probably faster than you could have done in-house.  It's along the same lines as loaning/giving out trial samples to magazine writers, but with far greater long term returns.

So set aside a hundred or so receiver blanks (or make the interface dimensions open source, which risks absolutely nothing on the IP front), and a few hundred barrel trunnions, gas blocks, and bolt/carrier groups, while you get the rest of the initial production into assembly.  Then soon after the initial shipment of guns is going around, and people start to get hands-on and learn what they like and what could be improved or changed...start selling "RDB Development Kits" to builders.  Maybe not even as a public thing, but to well-known pros or project bloggers.  People with the vision & means to do something with them.  By the time the novelty of the OEM configuration starts to wear off, you start seeing posts and videos about caliber conversions --you know, those things that manufacturers never seem to deliver on?-- new barrel lengths & furniture configurations.  New receiver designs that allow for 'ghost gunnery' as well as adding capabilities that aren't in the original gun.  Much if not all of it made freely available without licensing conditions, ready to be incorporated into new products or improved designs.

As the development interest fuels free press for the platform, more and more people start seeing versions of the gun that more closely match what they're after, they start thinking of owning multiple guns for different purposes, they start showing up in more & more venues like competition, home defense, policework, and hunting.  All the while, demand for the OEM configuration gun as well as parts & accessories continues to grow from the growing interest and new markets.  Manticore products sell a lot of CZ BREN 805s, and keep them off the used market.

Colt's M16 did *not* become popular because it was open source.  It languished for decades doing nothing more interesting than the M4 conversion until the AWB ended, and the aftermarket was allowed to finally exploit the modularity of the gun for a plethora of applications.  Optics mounts, caliber conversion, free float rails, accuracy builds, belt fed uppers, and yes, 80% and stripped receiver builds as pistols, which created the whole stupid brace fiasco we currently get to enjoy.  All of it was because there were parts available for third parties to develop with, and the law barring development had been removed.  That aspect is what the 'open source' had allowed; a sufficient supply of spare parts, something Colt could have offered itself from the beginning.

We're seeing the early stages of the process already in the P320, and there's nothing "open source" about that design at all, as I'm aware.  It's all SIG proprietary, but the aftermarket caught wind of the modularity potential (aka product opportunity potential) and is producing multiple chassis and accessories for the gun, even before it's military adoption has been fully implemented.  It is certainly helping to drive sales interest in a gun, that otherwise is not significantly different from any other Glock from the last thirty years.

My 5yd and 25yd speeds already suck (I assume; I'm just barely dipping a toe into 'fast' shooting games at the moment), but for the shoot I am preparing for, multi-hundred-yard shots are in the offing, and it doesn't look like anything is closer for the rifle than 25-50yds (being mostly steel).  I do think the Cyclops is the more natural, better all-around optic for what I would consider realistic use cases, but the 2.5 is probably better for this specific case (my untrained & imperfect eyes at intermediate distance).  I'm more concerned with just picking out the targets than hitting them.  And even more concerned with avoiding range penalties and DQs than my times during this learning phase, lol.

I think the cheekpiece could be a pretty simple Kydex fab-job.  Find a good rubbery-epoxy that plays well with it and the cheek pad material and I think you'd have a winner.

My point about the bolt catch, sling loop, and fences on the sides of the lower, is that if they were absent, the overall width would decrease by 1/8-1/4" on each side, and be far more flat.  Seems worth it to me just because I don't use any of those things .  The AUG vids I see look kind of awkward as far as the bolt catch; what's really needed is something up front, maybe in front of the selector, or off to the side of the mag release?  It's just a really long trip back to that button, is all.

I bet mud on the op-rod is the more significant issue.  Making the cocking handle a full-tube of material would better protect it (as far as it wouldn't move during shots like the exposed op-rod does), and the arrangement similar to that on the MP5/G3 certainly didn't have a reputation for tying up the gun.  Well, so long as the external cocking handle tube support didn't get bent or dented, at least.

Like all things, tension springs can be okay when designed properly.  They usually aren't, and KT's execution looks typical for failure where the end-hooks make a 90deg bend into the coiled section.  That angle tries to open up every time it's stretched, and sees more mechanical advantage trying to bend it than the rest of the spring; so it fatigues out at that bend, and prematurely.  Lighter-weight hammer struts and head (aluminum & titanium?) would both reduce the lock time and the amount of work needed from those springs (if I'm thinking correctly, a 1/2 mass titanium hammer would swing 2X faster than the steel one, or require 1/2 the force to accelerate the same amount)

Aftermarket support is a group of products that support the manufacturer's product in ways that the manufacturer doesn't.  Different fore-ends, sights, rails, triggers, etc, is "aftermarket".  Selling the rifle as parts so someone can cobble one together at home isn't supporting the "aftermarket", it's undercutting your potential profits and shafting your distribution channel with a "product" that undercuts their ability to retail your product.

In ten years perhaps the situation might be different, but right now, I don't see it.  Besides, it's a moot point; KT isn't going to do something like this given that they've never done it before.

Real quick & dirty photochop of the RDB PDW concept; the whole lower, receiver, and breech basically slide forward about 5" relative to the gas block/muzzle.  Mechanically, nothing would change except the gas port distance.  This image was constructed 'paper doll' style using a disassembled view of the major components; the length is lost from the barrel right in front of the breech-end.  The muzzle could be brought in even closer, near-flush with the gas block, but there would be very little room for a foregrip that wasn't part of the trigger guard (P90-style).  Would probably still be about a 10" long barrel even at that point.



At an 8-9" vs. 12-13" gas port distance, I think subsonic cartridge cycling would become viable.  Chop the buttpad back to the receiver like I've shown, and I think you could make a very compelling argument to the ATF that this is an "arm pistol" type firearm.  The big downside I foresee is balance; bringing the muzzle and gas system back 1/3-1/2 their length will definitely make the gun butt-heavy.  Granted, it would also be much lighter & faster to swing around, but it could be annoying.  Especially since the pistol-grip neutral balance is one of my favorite aspects of the RDB.

Well, they'd only be 'cobbling together' the barrel assembly...you wouldn't say that available off-model barrel options would hurt demand for the base product, would you?  Kel Tec generated a HUGE amount of buzz when they first announced the 'survival' model; do you remember why?  It wasn't because of the goofy stock, though Kel Tec obviously chose to pursue that aspect first (because it was easy).

It was because it was chambered in 6.5 Grendel.  Kel Tec hadn't marketed the gun as being chambering-swappable, the way the ACR/XCR/ARX/MDR/etc have been, to nearly universal disappointment.  So when they revealed they already had an alternate in the works, people got very excited about it.  Maybe it doesn't work and that's why it hasn't been deployed yet, who knows.  My point is, no one can even TRY to develop the product in that way so long as there are no parts to do so; your only option is to sacrifice the one working barrel for speculative development.

Worst case, Kel Tec 'loses out' on the ability to sell caliber conversions (that they would have had to spend lots of time & money proving out) while aftermarket products drive demand for their guns to new heights...or maybe even just the remaining parts (which is even better, from an overhead cost and warranty standpoint)

Best case, Kel Tec either licenses or just uses unprotected conversion designs to offer new product configurations, and can justify expanding production for the parts supply-chain.  Now they are selling multiple chassis and barrels to buyers who want multiple configurations, but want a common platform format.  The dream business model of the ACR bunglers, realized at long last.

In the video with MAC and the KT guy, I thought they mentioned a 6.5 CREEDMOOR version (maybe with a 22" barrel) in addition to the 6.5 grendel (though I think back then, the Grendel was getting more love). But without free-floating the barrel and changing some things, I wouldn't think that would be anything more than a 500Y gun (since I've seen people doing that with 75gr ammo in the 5.56 version).

I like the LENGTH of the OEM RDB handguard for handling (since you can get your support arm further out), but I think losing 1-1.5 inches would be good.  I just hate the width, girth, the picatinny rail on the bottom, and no options for side mounting except drilling on it in your garage.  If they wanted to go with polymer, they could have designed something thinner (like with the C and S models) with a heat-shield that also served to reinforce some m-lok holes on the bottom and sides.
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Yeah, for 100Y to 200Y, I'd want 2.5X as well.  Most people say 1X per 100Y, but for me it's more like 1.5X per 100 yards.  At 300, some may like 3X, but I'd want 4X-4.5X...for 500Y to 1000Y, I have a very clear 12X SWFA SS scope that I love.  I'd like to see the 2.5X PA compared to the two Leupy FX-II 2.5X scopes--I'd think they'd be lighter and maybe clearer than the PA (I think they're like 7-8 ounces) and would go in some low lightweight rings. They go for like $289 to $389 though...so a bit more $$ than PA, no illumination, and likely not as rugged.

The 2.5x is pretty heavy, which is one of the reasons I swapped to begin with.  A wider eye-relief box was the other reason (which would be mooted if there was a way for me to repeatably find the same spot on the featureless comb with my cheek)

I finally got some rounds through mine the past few days. Really like the gun, very smooth and does well as a suppressor host. I don't really hate the handguard, but would prefer a slimmer (still polymer) version with MLOK slots instead of the pic rail underneath. I think there is some aftermarket potential for sure.

Mini competition-outing update;
-Gun ran fantastic, no malfunctions, no accuracy issues I'm convinced weren't 100% my doing.  My sling was not attached to the handguard which may have helped
-I wasn't the only person there with an RDB, his ran fine as well
-Definite advantage in multi-position shooting, as well as obstacle navigation, over full-length guns (but we knew that already)
-Significant advantage in tunnel-type crawl stages; I was able to hold my rifle pistol grip in one hand, magazine in the other, and shimmy down on knees & elbows while controlling the muzzle against snags, since it is so balanced
-Gun is especially nice in prone, since you aren't extending your weak arm much at all
-I was able to hit torso targets in succession out to about 300yds (they said 400 but I don't buy it) on the first shot, prone.  Might be luck, as I was only zero'ed to 4" plates at 100 yds)
-Doing multiple front-to-rear sling hang transitions without a swivel will rapidly twist the sling until it is strangling you
-KT sling clasp metal got torn the hell up by the harder steel sling loop on the frame
-KT sling clasp tore up the softer plastic on that side of the gun; I think I'll be doing a wire-loop attachment in the future, with a swivel
-Single point sling hang at the pistol-grip loop, with sling looped around the neck & one shoulder is quite comfortable, both front & rear.  Muzzle hangs down back, or straight down the front out of the way of legs & arms
Improvements;
-The gun is short enough I kind of want to make a leather 'holster' for the muzzle when carrying it slung after shooting.  Sort of along the lines of the old saddle-ring holsters that cavalry used.  Can't put it down the front of my belt for obvious reasons, though
-Failing that, a second sling point a couple inches behind the first one would help keep the gun from trying to swing while slung.  It would also keep the strong-side sling strap away from the magwell when the gun is brought up
-A sling setup that lets me toss the rifle over my weak shoulder, without it spinning muzzle-down like this single-point setup would do
-Smaller forearm is a definite need
-Pistol-grip bipod would be very nice
-Brass catcher is badly needed (luckily I had long sleeves)

I think I will be replacing the muzzle device with one of the slim Faxon flash hiders.  1/4" longer, but looks lighter, and of course, more like the Halo battle rifle this gun already resembles .  If there's meat to do so, I am seriously considering chopping the barrel back to 16".  Maybe even 14" with the flash hider permanently mounted (but only if there is some way I can still mount a can over it).  For sure I'll be getting that shorter handguard as soon as I can.