Saturday, September 25, 2010

YHM Lightweight Railed Float Tube Review

YHM Rifle-Length Lightweight Tube on my RRA 16" 9mm Upper w/YHM wrench
Lots of holes, and the rails are milled out to cut weight.
I wanted another rifle-length quad-rail free-float tube to install on my 9mm upper, so that I could use the 9mm upper as a stand-in for training purposes. I wasn’t entirely satisfied with the Midwest Industries T-12 tube, because the rails didn’t seem to be true Picatinny-spec. I have to use a piece of a soda can as a shim to get the Vltor light mount to work with the MI handguard. I was told that YHM handguards are better in this respect, so I bought a YHM rifle-length tube to try out.

I tried the Vltor light mount on the YHM handguard, and it does indeed work properly without the silly shim. Everything else seems to fit fine on the YHM also.

I was afraid that the indexing/recoil lug on Larue mounts would not work with the milled-out rails, but the lug does still engage some of the rails on the lightweight tube. In .233Rem/5.56mm, there’s not enough recoil for the lug of the Larue mounts to really be necessary as a recoil lug.
Larue mount lugs just barely engages the milled-out rails
Along with the handguard, I ordered the YHM wrench. The YHM wrench has a spanner for the lock-ring at one end, and a barrel wrench at the other end. I would not count on using the YHM wrench to disassemble your upper, as you can’t apply much torque with it, although it may be enough to install the new barrel nut. I broke pins off my PRI barrel wrench trying to get the RRA upper apart (related post, PRI barrel nut wrench). When I got a new wrench back from PRI, it took a 3 foot length of pipe over my breaker bar before I finally got the barrel nut to come loose with a crack. The Model 1 Sales upper that I had taken apart before was almost as difficult to disassemble. The torque-spec for the barrel nut is more that 30 foot-pounds, but not more than 80 foot-pounds in order to get the hole or notch to line up properly with the hole in the upper for the gas tube. The RRA and Model 1 barrel nuts were likely overtorqued, the RRA in particular grossly overtorqued.

The YHM tool can not be used with a torque wrench, and would require a very large diameter pipe to use as a cheater bar for more leverage.

The YHM wrench works fine on the Midwest Industries lock-ring also, by the way.

Once I got the barrel nut/delta ring assembly, and front sight tower off the RRA upper, installing the new handguard was simple. It installs just like the MI handguard, except that it has two indexing screws, at 3 and 9 o’clock, instead of just one at 6 o’clock like the MI handguard. The barrel nuts of the YHM lightweight and MI T-Series handguards are nearly identical. The indexing screws for the YHM are slotted, where the MI handguard has allen-head socket screws. There were no tools or threadlocker included with the YHM handguard. The rail covers shown in some of my pictures were not included either.

The only minor issue I had was aligning the barrel nut so that the top rail of the handguard matched up with the rail on the upper. The 9mm upper is blow-back operated, and had no gas tube hole to use to align with the hole the barrel nut. If you are picky, it may take 2 or 3 tries to get the rails to line up just right, but the same is really true of most railed handguards.

The lightweight YHM does not give the full-length top rail effect. Although, as you can see in the photo below, the MI T-Series handguards don’t have a slot over the lockring anyway, so it really doesn’t make that much difference.
YHM Lightweight on Top, MI T-12 on Bottom
You may also note that the slots in the rails on the YHM lightweight tube are not marked ("T-Markings"). The center of the rails are milled out to save weight. This may be a problem for some.

The YHM lightweight handguards have holes at the front end for screwing in YHM’s sling mount. These holes are NOT QD sling swivel sockets for the swivels that release with a push-button. I believe that the top and bottom holes are for the YHM endcaps, and the holes on either side are for the YHM screw-in sling swivel studs, but don’t use either an endcap or a sling swivels, so I’m not really sure. Sling mounts and endcaps are sold separately.

I’m quite happy with the YHM Lightweight handguard. Depending on how the Spike’s Tactical slim handguard turns out, there’s a good chance that I may buy another YHM lightweight for my LMT 10.5” upper. I have no plans to buy another MI handguard until they start cutting the rails to proper Picatinny specifications.

EDIT 1/13/12:  I liked the 1st one so much, I got another for my Spike's 5.45mm upper.  When I decided to put a free-float, railed handguard on my SBR/pistol upper, I bought a mid-length lightweight handguard for that.  Yes, the Daniel Defense Lite handguard is slimmer, but I have not found the width of the YHM handguards to be a problem, and the YHM tubes are about a third the price of the DD Lite.  For me, it's an easy win for YHM.  Have not found anything yet that won't fit the YHM rails.

The Spike's slim handguard that I mentioned, comes with rail covers, and I think has QD sling sockets and an included sling swivel, but costs nearly what the DD Lite does.  I was tempted, but ultimately decided to skip it.

The free-float tubes with bolt-on rails have started to become popular.  My issue with these, is that when you start to bolt on more rail sections, they start to become heavier and more expensive than a quad rail handguard, while still lacking the versatility.  I also think they usually look sort of goofy, but maybe that's just me.

If you are looking for a YHM Lightweight handguard, Primary Arms has the cheapest prices that I have seen, so far, and service from them has been excellent.

Related Links:
Yankee Hill Machine Home Page

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