View Full Version : Flash hider has got me stumped
I'm getting my 2nd 10.5" LMT upper together and this dang flash hider is getting the best of me (won't line up).
This is with the crush washer it came with (used upper/barrel)
It lines up but upside down...
http://www.tacomaworld.com/gallery/data/500/medium/Train_Park_August_13th_2011_020.JPG (http://www.tacomaworld.com/gallery/showphoto.php/photo/181344/cat/500)
New washer
http://www.tacomaworld.com/gallery/data/500/medium/Train_Park_August_13th_2011_021.JPG (http://www.tacomaworld.com/gallery/showphoto.php/photo/181345/cat/500)
This is hand tight; it's already past 12 O' clock. Not sure what to do other than ad like a shim washer?
http://www.tacomaworld.com/gallery/data/500/medium/Train_Park_August_13th_2011_022.JPG (http://www.tacomaworld.com/gallery/showphoto.php/photo/181346/cat/500)
If you're using a crush washer, try crushing it. You can keep tightening those things like a full turn beyond where it first snugs up.
It's a YHM crush washer but I don't think it'll make it another 1/4 turn let alone a full or half rotation...:( I WILL try though.
Sounds like you're using the crush washer wrong. Used correctly, it's impossible NOT to be able to get it clocked correctly.
Screw it down finger-tight. You then have at least 360 degrees of rotation possible. You need at least 90 degrees of crush. Tighten-loosen-tighten-loosen until your a little over 90 degrees short of clocked, then go the full 90+ degrees clocked and stop. Don't loosen once clocked. You're done.
I know how it sounds but this is not my first rodeo.;) Recap: old washer centers upside down, new washer clearly goes past centerby two slots when tight. I'm thinking of finding a thin shim washer to work with the new crush washer or maybe Teflon tape with new crush washer as a last resort.:mad:
I know how it sounds but this is not my first rodeo.;) Recap: old washer centers upside down, new washer clearly goes past centerby two slots when tight. I'm thinking of finding a thin shim washer to work with the new crush washer or maybe Teflon tape with new crush washer as a last resort.:mad:
follow this advice...........
Sounds like you're using the crush washer wrong. Used correctly, it's impossible NOT to be able to get it clocked correctly.
Screw it down finger-tight. You then have at least 360 degrees of rotation possible. You need at least 90 degrees of crush. Tighten-loosen-tighten-loosen until your a little over 90 degrees short of clocked, then go the full 90+ degrees clocked and stop. Don't loosen once clocked. You're done.
Alrighty then. This is the first time I've had one not within a 90degree turn of centering. So, should I use the old washer and try for a 180degree-to-center or the new washer and go ~340degrees?:confused: I feel like I'm going to tweak my upper with that much torque...
ThreeLeafPayback
08-13-11, 19:27
Alrighty then. This is the first time I've had one not within a 90degree turn of centering. So, should I use the old washer and try for a 180degree-to-center or the new washer and go ~340degrees?:confused: I feel like I'm going to tweak my upper with that much torque...
A2 hider.
You are using an action block? If yes then turn it like the other posts say.
If you still cannot get it to index then you can use peel washers to make up the difference. However it really should index with a new crush washer as is.
No, I'm not using an action block. Once I get my gas block situated, I'll try cranking on the A2 and see if I can get another 180 degrees and if that doesn't work, I'll look into a peel washer I guess?
If you have a vice you can make some wood blocks to clamp your barrel in and then crank the hell out of it. You will be surprised how far it will turn with the crush washer once you are able to put some torque to it.
If you have a vice you can make some wood blocks to clamp your barrel in and then crank the hell out of it. You will be surprised how far it will turn with the crush washer once you are able to put some torque to it.
That's good idea. I'll try that, thanks.
Quiet-Matt
08-13-11, 20:27
I too recommend the tighten, loosen, repeat method. Especially if you have a long way to go. I have gone too far too fast and had a crush washer crack.
I know how it sounds but this is not my first rodeo.;) Recap: old washer centers upside down, new washer clearly goes past centerby two slots when tight. I'm thinking of finding a thin shim washer to work with the new crush washer or maybe Teflon tape with new crush washer as a last resort.:mad:
If you think you need a shim to use with a crush washer then you don't understand how to use a crush washer.
You can use a receiver block, but you'll be much better off with a barrel block. You have to use something to secure it or you'll never be able to get enough torque. Take a couple of 4-inch lengths of 2x4 if you have the room on the barrel, or 2x2's if not, and cut a pair of matching V grooves across the grain. Slip an old bicycle innertube around the barrel, put the whole thing in a vise and clamp the barrel in the V-grooves tight just behind the end of the barrel.
/
DO NOT USE AN ACTION BLOCK.
Clamp the barrel, not the action.
I understand the concept of a 'crush' washer, I just don't think there's room to 'crush' to where it needs to go but I'll take the advice given; clamp the barrel down and try to get it there. Hopefully that'll do it.
Thanks all.
I understand the concept of a 'crush' washer, I just don't think there's room to 'crush' to where it needs to go
These two statements are mutually exclusive.
PRGGodfather
08-13-11, 23:55
No need to use shims with crush washers. Choose one or the other.
To make our lawyers happy, the following is NOT advice, and we assume no liability if you use it. We always encourage the use of a professional, EXPERIENCED AR gunsmith:
Use a barrel block.
The "flare" or bell portion of a crush washer flattens against the device, as it has a larger OD than the barrel shoulder. The bell OD is usually larger than the shoulder OD, so the washer will not want to crush. It is possible to put a crush washer on this way, which is backwards; and the washer might even crush a little, but not very well this way, if at all. Folks very often try this and then call us wondering why this doesn't work.
Try a quarter turn at a time, and then back it off to crush the washer incrementally -- instead of putting 140 lbs. of torque on your barrel threads all at once.
Final torque into position should be about 30-45 lbs.
We have also received calls from many alleged gunsmiths and engineers, so you're not alone in this. Everyone has to start somewhere.
Sometimes, sanding the narrow end of the washer can help. You must sneak up on it, but this is my least preferred method, and I never actually use it myself.
Good luck!
I truly appreciate all of the advice and I'll be using it tomorrow when I get a hold of my neighbor's vise.
We have also received calls from alleged gunsmiths and engineers, so you're not alone.
PRGGodfather, thanks for saying so as I'm feeling pretty foolish posting for help about a flash hider lol.
You need this (http://www.brownells.com/.aspx/pid=12470/Product/AR_15_M16_BARREL_VISE_JAWS) from Brownells, or something similar.
http://spinstage.http.internapcdn.net/Spinstage/userdocs/products/p_795015100_1.jpg
You need this (http://www.brownells.com/.aspx/pid=12470/Product/AR_15_M16_BARREL_VISE_JAWS) from Brownells, or something similar.
http://spinstage.http.internapcdn.net/Spinstage/userdocs/products/p_795015100_1.jpg
Normally, I'd never pass up a chance to buy another tool, but the only time I've ever seen one of those $22 barrel clamps used it marred the barrel permanently, even with a line. I've never had that happen with the 2x4 pieces.
Thanks Eric but I'm going to try the wood blocks and rubber tube route suggested by Hmac. I've just got to cut my grooves on the blocks and wait until my neighbor is free.
Also, check to see if you need a thin open end wrench. When I installed my Battlecomp, I used an open end wrench of normal thickness. As the crush washer expanded in diameter as it crushed, it pressed against the wrench, made installation more difficult than it needed to be and marred the BC & crush washer.
Try lining the grooves of the wood blocks with masking tape or leather to help keep the barrel from slipping while torquing
Also, check to see if you need a thin open end wrench. When I installed my Battlecomp, I used an open end wrench of normal thickness. As the crush washer expanded in diameter as it crushed, it pressed against the wrench, made installation more difficult than it needed to be and marred the BC & crush washer.
Try lining the grooves of the wood blocks with masking tape or leather to help keep the barrel from slipping while torquing
Good advice, thanks. I have an adjustable wrench I think will give a little when the washer expands. I'll be using a piece of garden hose to clamshell the barrel to use as a buffer between the wood and barrel; I think that'll work.
I strongly advise that you DO NOT use an adjustable wrench. It WILL slip, mar the finish and round the corners. If it would help, I'll try to dig up the camera & wrenches & take a couple photos. I'll need a bit of time to unpack them
I strongly advise that you DO NOT use an adjustable wrench. It WILL slip, mar the finish and round the corners. If it would help, I'll try to dig up the camera & wrenches & take a couple photos. I'll need a bit of time to unpack them
I'll see what my neighbor has. He's got a garage full of tools. Thanks again.
Just went thru the same process w/ my "previously owned" BC 1.0. I might suggest using a silver ink marker to mark the dead center top of the BC (or other FH) front and rear. Then mark the top of the bbl. the same way closest to the threads. Now you have an easy visual reference point when you get to the last turn as the crush washer flattens out. Much better than guessing if you went too far past or need to go a hair more. Do the incremental tighting process also, don't do it in one shot. I put a very light film of oil on the threads and crush washer before tightning. For clamping in a vise, if you do not have rubber jaw covers, take an old leather work glove and cut the fingers off and split the side seams. Now you have a flexable, tough and easy to position wrap for the bbl. in the vise. An old bicycle inner tube can also be used with a few wraps around. I had written to Battle Comp asking for instructions, they responded the next day with clear directions as seen in their post to you.
This is what I'm talking about with the wrenches. On the right is the tappet wrench. It's thinner. On the left is the standard wrench. It's thicker and when I used it to install the BC, the crush washer pressed up against the wrench. You can see the shiny spot where it damaged the crush washer slightly. It also marred the finish of the BC although tape was used to protect it
http://i115.photobucket.com/albums/n289/SgtSongDog/AR%20Build/DSC_0120.jpg
Gotcha. I'm still waiting for some vise time.
You need this (http://www.brownells.com/.aspx/pid=12470/Product/AR_15_M16_BARREL_VISE_JAWS) from Brownells, or something similar.
http://spinstage.http.internapcdn.net/Spinstage/userdocs/products/p_795015100_1.jpg
That's the ticket. If you don't have enough space on the barrel for full length jaws, you can always chop a pair of those so they'll fit between the handguard and the end of the barrel. Aluminum is soft.
Skinny wrenches are also the way to go, so you don't ding up the crush washer. If a 3/4" fits loose, try a 19mm to avoid marring your flash hider.
Ok, so I went to my neighbor's garage, drilled my countersink holes for my LPGB, then went to work on the flash hider. I first used the new washer but I didn't get anywhere near where it needed to go but the old washer made the 180 degrees with not too much trouble so thanks all!
BTW, here it is;
LMT/Vltor
Colt BCG
PRI GB CH
http://www.tacomaworld.com/gallery/data/500/medium/Train_Park_August_13th_2011_001.JPG (http://www.tacomaworld.com/gallery/showphoto.php/photo/181604/cat/500)
My other LMT upper:D:
http://www.tacomaworld.com/gallery/data/500/medium/june_2011_006.JPG (http://www.tacomaworld.com/gallery/showphoto.php/photo/165305/cat/500)
Another vote for the tappet wrench.
I really need to invest in a vise and more tools. But this was my third upper I've done and the first time I've needed a real vise.
You can take a hammer to it to get closer to your 'crush' point.i mean with it off and on a flat surface.
You can take a hammer to it to get closer to your 'crush' point.i mean with it off and on a flat surface.
If I only had the new washer, I would've totally done that, thanks.
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