I'm piecemealing my 1st AR together. I'm doing it on the cheap knowing full well I'll eventually swap out barrel, BCG, trigger...So I bought a Chinese FF NSF keymod handguard (cheap). It came with 2 ea. of these washers; 2 crush type and wave type. I've dug around and haven't found the order they stack in. I'll need shims regardless because of barrel slop. Although I've only hand checked it. My guess is the shims in the nut then the supplied stack. In what order? Thanks for any direction.
I wish I could offer some advice on your issue. I have never seen such stuff for a handguard.
This is just me but if you can swing it I would return or steel that handguard and get a matrix handguard off joebobs in your choice of length and style.
They will be under 60 bucks. And much simpler to get installed.
This is what I received. Everything fits I just don't know how to stack the 4 items. I know I need to buy shims. Maybe the 4 washers aren't needed? I bought my lower from Matrix and slick sided upper from Joebob's. Nice. My approach on this new hobby is to start low and set a benchmark. Then I'll upgrade in steps and see results. Thanks for any and all input.
I did some more research. My take- I can toss the washers and buy a shim kit. Calculate actual barrel nut torque and use an adjustable wrench. Estimate my hand pressure on my bathroom scale and torque the nut to 35-80 ft-lb; on the low side.
2 washers are very slight conical other 2 are wave. I've seen video of steel milspec nut install; no washers. I still need shims for slop axially but that's no big deal. I'm thinking maybe lost in translation? Ebay from China.
01-22-2019, 03:47 AM (This post was last modified: 01-22-2019, 03:50 AM by jeff68.)
BCHunter Wrote:My guess would be those are the shims for timing the barrel nut / fine tuning so the handguard is top dead center.
Is the handguard round inside? The flats on the outside make me think the washers are for timing the hand guard.
yes it is round; at least it twists on snug like.
….so I could just toss it and buy standard shims? I really don't like the wavey and crushy stuff. Flat assorted shims and be done with it?
You should be able to rent a torque wrench from local auto parts store,...auto zone, napa, oreilies,etc. Or a basic one is 20-40 dollars, crow foot head if it didn't come with the handguard is 10-20 from midwayusa or brownells. Not a step you want to be guessing if you have proper torque or not.
If you have slop read the thread on bedding the barrel with blue loctite. You want a tight fit of barrel to receiver, normally you would put one set of each washers on each side of the nut. But I dont think you want washers between the upper and barrel in this case.
On old style barrel nuts you have to shim to line up the gas tube. Newer ones generally you dont have to time the barrel nut, the only timing is to align the handguard.
01-22-2019, 05:27 AM (This post was last modified: 01-22-2019, 05:29 AM by bj139.)
Hook a luggage scale to your adjustable wrench and apply torque with the scale.
With a 1 foot wrench and 50 lbs on the scale you have 50 ft-lbs.
I have one like this. https://www.ebay.com/itm/Portable-Luggag...rk:10:pf:0
Looks like the screws will go through the handguard into the nut? If so then the washers are definitely timing ones, and so after you snug it up there's some few 0.001's extra travel you need to wind up at after torqueing (ergo the shims), so the handguard is lined up/timed properly. Don't use any washers between the barrel and upper, any that you put on will go on after the barrel is inserted, then the washers, then the nut.
I don't see any reason you couldn't go with standard barrel nut shims, but yeah, for first time definitely use/borrow/rent a torque wrench and crow's foot. There are several threads on bedding the barrel with some loctite blue... you might also want to check the upper to ensure it is square on its end, or lap it to get there.
All in all I'd second A5 in going to joebob for matrix or one of their handguards, or even the Ar-stoner from midway. Still pretty economical.
"Down the floor, out the door, Go Brandon Go!!!!!"
01-22-2019, 09:29 PM (This post was last modified: 01-22-2019, 09:32 PM by jeff68.)
Lastrites & grayfox & all- OK I assembled the receiver, barrel and nut again, no washers. I have 0.1" axial play to take up with only about a 1/32" between receiver face and nut face. That's too much shimming? It's a $59.99 BCA 16" parkerized 6.5 type II and an upper from JoeBob's . Neither of those are suspect although barrel extension is by no means a tight fit. The nut has 1.06" across flats. from what I gather it should be 15/16" but whatever. I'm stubborn so swapping out handguard is option C. Option A is shim the 0.10". Option B is buy a domestic NSR nut and hope screw spacing length wise are the same. I'm thinking a new nut. Any thoughts? Thanks again.
This is all dry fitting. I'm a ways from doing any final assembly. Need to machine lower and spend a few more bucks on misc.
