YHM handgaurd problem

[jet80tv]

Hi, Im new to the site but not AR's. However I am new to ff tubes. I have a YHM diamond rail carbine length. I had originally installed without the yhm wrench. They dont recommend torquing, hand tightened barrel nut then tightened to next hole, came loose while shooting, put it to next hole and can get no tighter and barrel nut appears gtg, but the handgaurd itself i cant seem to get perfectly straight with my flat top upper starts out even then just slightly off when tightened. I have tried holding it in place with rail covers, scope ring bases you name it, with and without anti-rotation screws in place. seems to be off only a hair 32nd of an inch? doesnt seem to affect same plane sights, I have sratched up 2 jam nuts now both using other methods and yhm's wrench. should i just leave it off a "hair" or maybe send the upper to yhm? any input thanks

[Sanpete]

If the handguard is still crooked, then your barrel nut is not torqued and/or aligned properly. Did you install the two set screws on either side?

edit: do they really say only hand tight? that's nuts.

[jet80tv]

They say hand tight then go to next hole with wrench, the handgaurd is not crooked it just turns with the jam nut you know like left or right in this case to the right when I tighten the jam nut which is left, thanks

[hikeeba]

Perhaps you need to re-read YHM's instructions and try again.

Here are installation instructions from YHM's website. These instructions apply to YHM one-piece solid and lightweight free-float handguards:



A qualified gunsmith familiar with your firearm should install this forearm. Failure
to install this forearm correctly voids any warranties of the product and removes
any liabilities against the manufacturer. This forearm cannot be installed on a rifle
utilizing a pinned, welded, or otherwise permanently mounted muzzle accessory
unless a two-piece gas block will also be installed. Be certain the firearm is unloaded
and always pointing in a safe direction before starting this removal and installation
process.
(1) Remove the existing forearm per the firearms manufacturer’s instructions.
(2) Unscrew the muzzle brake or flash hider and set aside if one has been installed
on the firearm.
(3) Remove the front sight by tapping out the 2 tapered dowel pins at the bottom of
the sight that hold it onto the barrel using a 1/8 diameter drift pin punch being
sure to drive the pin out from the SMALL END
(4) Remove the sight assembly and gas tube from the barrel and set aside. Retain the
tapered dowel pins for re-assembly.
(5) Remove the front plate of the old forearm and set aside.
(6) Remove the combination delta ring /barrel nut using a proper armorer’s barrel
nut removal wrench.
(7) Clean the threads on the upper receiver and install the new barrel nut until it is
firmly tightened by hand.
(8) Using our forearm wrench YHM-9621 tighten the barrel nut to the next aligning
gas tube hole in the barrel nut and upper receiver. Take special care in aligning
the gas tube hole as this will influence the orientation of the rails of your new
forearm.
(9) Install the jamb nut all the way on the barrel nut until it is flush with the end of
the barrel nut closest to the upper receiver. Then unscrew it towards the muzzle
one and one half turns.
(10) Install the forearm onto the barrel nut until it makes contact with the jamb nut
making sure the sling mount holes are facing the muzzle end and the holes for
the anti-rotation screws are at 3 and 9 O’clock.
(11) Align the forearm rail with the upper receiver, hold the forearm and tighten the
jamb nut very firmly against the forearm using our forearm wrench.
(12) Install and tighten the 2 anti-rotation screws. Use a low-strength thread locker if
desired
If you’re installing a forearm end cap YHM-9484A or B, follow the instructions
supplied for that product at this point of the installation. When finished installing the end
cap, return to step 12.
(13) Re-install the front sight being careful to align the gas tube through the barrel nut
and upper receiver.
(14) Re-install the tapered dowel pins being careful to install them in the proper
direction of the taper. Set pins firmly.
(15) Re-install the muzzle brake or flash hider to manufacturer’s specifications if
applicable.
Before test firing the firearm, be sure all components that were removed are
reinstalled and tightened correctly. It is recommended that you bench fire the
firearm first to be sure everything is operating smoothly. Always handle your
firearm with care being sure the muzzle is pointing in a safe direction and wear
approved shooting glasses and hearing protection when using your firearm.

I've installed a YHM Lightweight, and have had no issues with it. Initially I hand tightened the barrel nut, but then backed it off and snugged it up two more times, using a wrench and applying a little more torque each time. Next, I grabbed the torque wrench, and did the final torque being sure that I achieved proper gas tube alignment with a torque greater than 35 ft-lb and not exceeding 80 ft-lb. I think I achieved proper alignment at ~47 ft-lb. I spun the YHM lock ring/jam nut on per their instructions, spun on the forearm, and used a detatchable carry handle to align the forearm with the receiver. I installed the anti-rotation screws last. I am using a rail-mounted front sight on this particular rifle, and have had no sighting issues with the irons, thus no forearm rotation issues.

I hope my post helps you. I'm no expert gunsmith or anything, but if you feel I may be of further assistance to you, shoot me a PM. Otherwise, there are other resources on the web that could help you out, too. Good luck.

[jet80tv]

Thanks hikeeba, I'll strip it dwn and start frm scratch again, it's been a little frustrating but the desired outcome will be worth it.

[LMTRocks]

I've put those forearms on too and never had trouble with the barrel nut spinning off with the forearm after the gas tube is installed. Use a torque wrench and make sure that gas tube hole is dead nuts centered so the upper rail is in line with the receiver. I'd also send it back and have a Troy TRX sent as it installs easier and includes a wrench and will weigh less.

[jet80tv]

Well it's not that it spun off as the gas tube held it frm rotating further I think it's gtg now tho I haven't put many ends thru it since last tighten. I would go with a Troy but I already spent oh $170 or so between 2 jam nuts, wrench and handgaurd so not rdy to give up on it yet, Thanks