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Old January 24, 2013, 06:50 PM   #1
4V50 Gary
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timing a flash suppressor

I know how to thread, but how do you time a flash suppressor?

On the AR, the bottom of the cage is solid so as to prevent the blast from disturbing the dust. I suppose it helps with recovery for a follow up shot too.

So, how does one ensure that the solid bottom is at 6 o'clock? Just stop rotating it when it's in position? I'm also concerned about threading the barrel excessively.
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Old January 24, 2013, 07:19 PM   #2
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Use a crush washer. When the suppressor engages the washer you'll be able to tighten it to the place you like. The tension of the washer will hold the suppressor in place. If you ever take off the suppressor and reinstall it, you'll need to use a fresh washer. They're single use.
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Old January 24, 2013, 07:49 PM   #3
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Duh! (me)

Thanks.
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Old January 25, 2013, 05:40 AM   #4
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Gary,I can agree with the response,to a point.You actually can use a spark plug washer.(Its been done)There are laminated peel washers available.

I'll give you a tool.The pitch of a thread is 1/tpi.So,20 tpi means .050 per rev.If you divide that .050(or whatever pitch you are using)by 360,you will get the amount of washer thickness you need for 1 degree of change.From there,you can know your shim thickness.

Outfits like Carr-Lane anf Manhattan Supply,I believe,sell various case hardened,precision ground,sized by the .001 to use.I have turned some,just the right thickness.

Now,I will preview a thread I am about to write.Suppose you torque that on to 20 ft lbs to get it oriented just right.(I think I messed up a barrel).That is a good spark plug torque,2.3 white knuckles on a 6 in combination wrench.

Lets see,Pi is 3.1417,lever arm 12 in,in my head roughly 37 inches of travel for one revolution to move .050Lets call it 40 to make the math easy.I get an 800 to 1 mechanical advantage.Times 20 lbs,16,000 lbs linear force for 20 ft lbs.Now,thats not true,because there is not 100% efficiency,friction eats a lot.That poor thin walled tube that is between the minor diameter of the threads and the bore doesn't really get stretched with 8 tons of pressure.

But that stretch is at the last 1/2 in of barrel,releasing the bullet.

Go easy!
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Old January 25, 2013, 01:25 PM   #5
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Thanks!
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Old January 25, 2013, 01:33 PM   #6
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Do it right and use a peel washer. You can peel off thin strips until it's the correct thickness to time your flash suppressor correctly.

http://www.midwayusa.com/product/654...l-washer-ar-15
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Old January 25, 2013, 01:40 PM   #7
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If you use a peel washer, the final size will be about .001" thick so the muzzle device will be timed properly when tightened.

If it's a standard 1/2-28 thread, one full turn of the muzzle device is roughly 0.036 inch of travel.
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Old January 25, 2013, 03:02 PM   #8
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Use peel washers, it's quick and easy. And do not overtorque, use LocTite if you are worried about the brake coming loose.
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Old January 28, 2013, 09:06 AM   #9
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I just punch a shim out of shim stock punch & die set.
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Old January 28, 2013, 09:51 AM   #10
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A crush washer is $2. Do it right! Easier than peel washer.
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Old February 6, 2013, 02:18 PM   #11
AR15barrels
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Quote:
I know how to thread, but how do you time a flash suppressor?

On the AR, the bottom of the cage is solid so as to prevent the blast from disturbing the dust. I suppose it helps with recovery for a follow up shot too.

So, how does one ensure that the solid bottom is at 6 o'clock? Just stop rotating it when it's in position? I'm also concerned about threading the barrel excessively.
If you are cutting the threads, you can also cut the barrels shoulder so that there is no crush washer or shims needed.
I do this for customers as a service when they are having me thread a barrel or assemble a rifle.
On 1/2-28 threads, 0.001" of cut gives you 10 degrees of rotation.
When checking by hand as you cut the shoulder, stop about 10-20 degrees short as the muzzle brake will turn another 10-20 degrees when you wrench it on there tight.
I do this stuff for a living if anyone else needs help threading a barrel.
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Old February 6, 2013, 07:15 PM   #12
Roughedge
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I do about the same thing but I take a little off the break instead of the barrel as its easier to get in the lathe. I make most of my breaks and leave a little thread releif so I can fit it to the barrel.
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Old February 6, 2013, 09:12 PM   #13
AR15barrels
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Quote:
I do about the same thing but I take a little off the break instead of the barrel as its easier to get in the lathe. I make most of my breaks and leave a little thread releif so I can fit it to the barrel.
That works good when the brake is the same size as the barrel.
On muzzle devices that exceed the barrel diameter and have a finish on them, I prefer to trim the barrel shoulder so as not to leave unfinished metal on the back side of the muzzle device or remove the nicely rounded edges that may be present.
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Old February 6, 2013, 09:16 PM   #14
ScottRiqui
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I may have just heard different terminology all these years, but when you're talking about using a washer to adjust the final orientation of a threaded object, are you "timing" it, or are you "clocking" it?
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Old February 6, 2013, 09:17 PM   #15
AR15barrels
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Quote:
I may have just heard different terminology all these years, but when you're talking about using a washer to adjust the final orientation of a threaded object, are you "timing" it, or are you "clocking" it?
I think you can use both terms interchangeably.
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