Part 1 of my review of the Mod 2 Enhanced Buffer Tube w/ratchet Lock Castle Nut

What was included:
Impact Extruded 7075 Aluminum Buffer Tube w/Mil-Spec Type III Black Anodizing
Steel Ratchet-Lock End Plate with central Quick Detach Sling Swivel Mount w/Black Finish
Steel Ratchet-Lock Castle Nut w/Black Finish
Lifetime Warranty

Initial Impressions:
So what caught my eye with this receiver extension was initially the fluting on the tube portion. However once investigating the specs I was surprised that considering the addition of their anti-tilt lip for reducing carrier tilt, the weight still comes in at less than the V7 option at only 3 oz. The construction is super solid impact extruded 7075 aluminum w/Mil-Spec Type III hard anodizing.

Packaging is the clear plastic clam shell hanging type with easy to understand instructions accompanied by detailed pictures printed on a professional looking insert. Opening the package everything kind of falls out at you and you then realize that the heaviest part of this purchase are the included endplate/castle nut  combo. As of the time I’m writing this, they do not offer the receiver extension separately (although I wish they did). When reading PWS’ & retailer’s websites it alludes to the proprietary Ratchet-Lock End Plate/Castle Nut being made of aluminum as well, but this is definitely not the case. I emailed PWS again to let them know, and was told that they would definitely clarify the matter on their site.

The finish on the tube seems well done and covers the components completely.  Due to the unavailability of any sort of material/finish specifications regarding the endplate/castle nut combo, I can’t really compare them to anything.



"SUBSCRIBE" and look for my next update on this latest part of my build!

What's the wall thickness of your regular old buffer tube?  How deep are those flutes?  How can you flute a tube and still have free buffer travel on the inside and free stock travel on the outside?

I'm interested to know this as well.

Milspec receiver extension(buffer tube) inside diameter(ID) is 1.000" and OD is 1.145" to 1.150".   That gives a wall thickness of roughly .145" or roughly 3.6mm at the least.  This is PLENTY of wall thickness, especially when made from 7075-T6 aluminum.

There are several things that fluting will help with, aside from darn good looks.  

1:  Weight loss.
2:  Space for dirt and grit to travel out of the stock area
3:  By reducing the overall surface area, the stock doesn't make as much contact with the extension allowing a freer sliding movement without sacrificing strength.
4:  Strength theoretically won't suffer even though material has been removed, the surface area has been increased thus increasing stiffness.

PWS has been making fluted tubes for ages and I have never seen a functional issue with one, ever.  The only reason I haven't installed more for customers at the shops I worked at in the past was cost.  That being said, quality costs and I'm looking forward to see your review on YouTube, PM86!

It would seem to me, that if they feel like the ratchet lock nut and end plate combo is a good enough product, and the "enhanced" buffer tube is a good enough product, that they would sell each of them separately, as well as bundled together?

Increasing surface area through material material removal does not increase stiffness.  Any time you remove material from a part of given dimensions, strength and stiffness will be reduced.  The strength-to-weight can go up dramatically, though.

However, if two parts are of the same material and weight, but one is fluted (imagine two tubes which start out exactly the same, but one is stamped to create indented troughs and/or raised ribs), the fluted part will indeed be stronger and stiffer (depending on which degree of freedom you're looking at), but it's not because the surface area is increased.  The strength and stiffness is increased because the material is configured in multiple planes.  This is why corrugated sheet metal is stronger than flat sheets and why steel wheels are stamped instead of being flat discs.  In an extrapolation of the principle, this is why a truss bridge is stronger than the exact same amount of material being used to create a few beams.

NOTE:  My response is directed to point #4 as an engineering principle.  I am not questioning or debating the quality or performance of the PWS tube.

Thank you Stich, I'm working on the editing part of things! My first time doing video editing... The holidays don't help either!
Here is a few more pix for y'all though, enjoy!

Do you by any chance have a Mod 1 PWS buffer to compare it to?

I do not, but my understanding is the mod 1 has the proprietary attachment system with the QD attachment points.

Do you have any specific questions?

Is the little detent nub that locks the castle nut in place spring loaded or something else?

Eh, no specific questions, I don't think. I'd just be curious to hear impressions handling them side by side. I have the Mod 1 tube and like it, but I'm not in love. It's about 5.5 oz, but the idea behind it seemed to be finding new ways to do things (i.e. new attachment method, QD on both sides, etc). The Mod 2 seems to move in the direction of shedding weight and further simplifying the attachment process.

From the videos they've posted of the ratcheting action, the detent engages the slots to keep the castle nut from backing off.  

I'm hoping they do offer the parts separately as I like the idea of the ratcheting nut and plate but for those that would prefer a lighter setup, it'd be nice to just be able to purchase the tube by itself.  PWS has been pretty good at listening to the wants of it's clientele since they started so I doubt they'll only offer it as a bundle.



I've installed a couple dozen of the MK1 receiver extensions and like they very much.  Easy to install and it's an entire system all in one, which is really nice.  No need to hunt down and pay for an expensive QD mount on top of the tube and castle nut.

I like the fact that the Mod 2 parts are separate so if the user decides they don't like the single point sling mount, it can be changed or use a lighter one instead.

It seams to me to be of a spring steel material that has enough give to allow the teeth to pass by under torque, but not so much to allow them to back off by itself.

It also appears to be mechanically pressed into place through the endplate.

~PalmettoRed86

I have this receiver extension system on my lightweight AR.  That pin is not spring loaded but it does flex just enough to allow the ratcheting action on the castle nut.  I was also suspicious that this would eventually back off, so I put a witness mark across the castle nut and end plate to see if the castle nut did move as I used the rifle.  I torqued the castle nut pretty dang tight and so far, it has not moved after a few hundred rounds.  Bear in mind, I haven't mortared my rifle or abused it in this area.  It does allow me to remove the castle nut using a wrench with a bit of effort, so I believe this is a pretty effective way to secure the castle nut without staking.

Thanks guys, a description of the pin wasn't really very clear on the PWS site.

Fortress Tactical has these as $79 right now. Went and grabbed my third last night.

That's a sweet deal! I would definitely pay that for one of these.

I'll have to look into the whole setup on my next lightweight build!  You can, and I have purchased just he end plate and locking castle nut separately, they sell for about $29.99 for the pair, also comes in a little clam shell case.

If PWS came out with an A5 compatible version of this tube I'd have bought one already. Don't know what they're waiting on to do that.

Snagged one from Fortress Tactical, price was too good to pass up IMO.

The mod 2 PWS tubes are a step up from the original mod 1 416 units. Not only are they lighter, but they're easier to install. The set screws on the mod 1 were a pain in the ass to tighten. You had to take the Allen key out every half turn. They were also prone to stripping.

I used purple low yield Loctite on the receiver extension and on the Nut itself. This should keep the Nut from backing out.

I like the placement of the QD sockets better on the Mod 1, but I can live with it.

I'm really not a fan of the locknut and castle nut setup, but I could see a lot of people going for it!

I mentioned this in the lightweight build thread, but something else to think about if you want to ditch the end plate.

An HK buffer retainer is much stronger than a standard AR variety, and will engage with the 'anti-tilt' extension to keep the receiver extension from un-screwing.  I wouldn't rely on the buffer retainer by itself to retain the receiver extension, but with an aluminum castle nut it would allow you to shed some weight and at least one part.