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3/1/2007 12:35:35 PM EDT
Hi, I just picked up a KAC M4 QD flash hider that's going on my LMT 10.5" upper. The 10.5" barrel is threaded and came with an A2 FH. I don't really have any tools apart form a solid crescent wrench, could I still manage to get the A2 off without a barrel vise? Here's the complete KAC kit:



I'd like to know how to properly time the KAC FH, do I simply get another crush washer or use the supplied shim kit that comes with a bunch of colour labeled peel washers? I've handled crush washers before, but I'm not familiar with peel washers, what does the process look like if I were to use them? Thanks in advance.
3/1/2007 4:02:18 PM EDT
[#1]
Anyone have any experience with these?
3/1/2007 4:20:49 PM EDT
[#2]
No experience with the KAC FH, but I've removed and installed plenty A1 and A2 FH's using a standard bench vise. Just protect the barrel with a thick piece of rubber.

Here's my son installing his.




3/6/2007 5:56:54 PM EDT
[#3]
Wrap the front sight base in leather and clamp it upside-down in a vise.
That's how I hold barrels for muzzle device installation.
3/6/2007 9:32:23 PM EDT
[#4]
You might be able to remove the A2 flash hider without using a vise at all. I can remove my flash hider by just tightly holding on the receiver and giving a good tug on the flash hider with a wrench and then unscrew it by hand. But i guess it depends how tight the flash hider is on it. It looks like you just use the shims to correctly time the flash hider. So just use the correct shim with the right thickness to line up the flash hider correctly when you tighten it down.
3/6/2007 9:48:15 PM EDT
[#5]
I'm a cheap lazy bastard, destined to fuck up great things in my life.   I lay my rifle on the carpet with a magazine in it and kinda put my knee on it while wrenching away with the multi-tool.  So far I've replaced two different flash hiders that way.  Just remember to cover the flats of the actual flash hider with tape or something so you don't get ugly marks on them from the tool you're using.

ETA:  While we're talking about crush washers & flash hiders, does anyone know why you're supposed to replace them after using them once?  That's what I'd heard but I can't imagine any problems from reusing them.
3/7/2007 7:38:30 AM EDT
[#6]

Quoted:
While we're talking about crush washers & flash hiders, does anyone know why you're supposed to replace them after using them once?  That's what I'd heard but I can't imagine any problems from reusing them.


Because once you crush them, they do not apply the same amount of force to hold the muzzle device in place when you re-install them.
3/7/2007 7:44:20 AM EDT
[#7]
So would that be as much an issue with a supposedly "self-tighening" vortex?
3/7/2007 8:15:42 AM EDT
[#8]

Quoted:
So would that be as much an issue with a supposedly "self-tighening" vortex?


Not an issue at all because you don't use ANY washers with a Vortex.

3/7/2007 10:34:34 AM EDT
[#9]
Oops, wonder why they say that?  And they come with instructions??  I've never seen instructions come with any flash hider...

You're the expert, why do they advise 1) not to use the washer and 2) say no more than 10 lbs of torque?  I figure it had flats, it's meant to be installed with a tool, aka, tightly.

ETA:  Having you as a member of this site rocks.  I can't wait to sent you some barrels for shortening oneday.
3/7/2007 11:02:02 AM EDT
[#10]
I don't want to hijack the thread but I have a question...is the vortex available in the same lenght of the standard A2 FH?
3/7/2007 11:58:46 AM EDT
[#11]

Quoted:
I don't want to hijack the thread but I have a question...is the vortex available in the same lenght of the standard A2 FH?


No, but people have cut them down.
They did not work nearly as good.
See the big flash suppressors test thread for details...
3/7/2007 12:07:13 PM EDT
[#12]

Quoted:
Oops, wonder why they say that?  And they come with instructions??  I've never seen instructions come with any flash hider...

You're the expert, why do they advise 1) not to use the washer and 2) say no more than 10 lbs of torque?  I figure it had flats, it's meant to be installed with a tool, aka, tightly.


The whole Vortex design relies on proper sealing of the flash suppressor against the muzzle to eliminate any "eddy" as the gas leaves the muzzle.
By adding a washer, you are creating a cavity where the gas swirls around, therefore reducing the pressure available at the beginning of the four slots.

I don't know why they say to only torque to 10-ft-lbs, but it may have to do with accuracy.
When you put too much torque on the muzzle device, you are stretching the barrel.
Match rifle shooters install muzzle devices only hand-tight and use loctite on the threads to actually retain the muzzle devices.
This ensures that there is no additional stress on the barrel at the muzzle.

Vortexes are self-tightening because of the direction of the threads and the Vortex cuts.
Therefore, there's no NEED for more torque, so why bother trying to stretch the barrel any more than you need to?
3/7/2007 12:16:29 PM EDT
[#13]
I wouldn't have imagined that in a million years.  I guess I'll go take the washer off now...Or now that it's on, and it's tight, should I just leave it be?
3/7/2007 2:08:07 PM EDT
[#14]

Quoted:
I wouldn't have imagined that in a million years.  I guess I'll go take the washer off now...Or now that it's on, and it's tight, should I just leave it be?


Take the washer off.
3/7/2007 2:28:01 PM EDT
[#15]

Quoted:
I'm a cheap lazy bastard, destined to fuck up great things in my life.  


Thanks for the new quote of the day!
3/9/2007 9:44:11 PM EDT
[#16]
If you haven't been able too get it yet... i'll try too give a little help....    
This might be a little ackward so try 2 bear w/ me...  

I use the shims only(no crush)

1...  You will want the Top(#3/middle) slit and the Cut out too be lined roughly straight up and down....
2...  The average area that you will want the Top slit and Cut out   too be around are the 10-11 and 4-5 o'clock positions....  which will line the F/H straight up and down when torqued down...  
3...  4 this, you will (might have too) need too spend some time taking the F/H on and off and testing all the shims, untill the you get the desired(o'clock) angle with hand tightening....
4...  When you have found the shims that you will be using...  Put the Smallest shim on the barrel first and work your way up too the largest last....
5...  Put some Rocksett on both the threads on the barrel and F/H....  Amount is your choice...    Make sure you wipe off the extra, because it does harden good on anything it touches..
6...  Put on and tighten down.. until the F/H is aligned up and down...   Usually around 20lbs to 30lbs is were it hits when I put it at the 10.5 - 4.5 o'clock pos...    
7...  Let it dry for a day or two....    I usually let it go for 2-3 days....
8...  Enjoy........

Here's one way i guess....   It's worked for a few mounts and has held up constantly w/ and w/o a can....   never had too readjust or retighten,  so i'm not complaining....

Hope this helps alittle.......
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