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Discussion Starter #1
(The title is just tongue-in-cheek, so no one gets offended).

(I've posted this on a couple of forums now, and I still see questions about loose slant brakes, etc., so I hope no one minds if I copy and paste it here).


How to Make Your Compensator Fit for Dummies

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I originally posted this on K-VAR's forum and a poster called "Judge" thanked me by giving my post that title.

I started thinking that maybe other people might want to read it. So here it is in all its excessive verbage and thirty-dollar words:

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A common complaint among AK owners is that whatever compensator is on the rifle it's not tight. It "wobbles." If you don't want to sit there with a bucket of compensators and try each one until you find one that fits tightly, you will have to do some hand-fitting. The idea is that if the compensator fits tightly against the front sight base, i.e., that it "screws all the way down" just as the detent plunger locks it in place, then the rotational play and a small amount of wobble will be eliminated.

Rotational play is where the compensator wobbles WITH the threads, i.e., screws and unscrews. Rotational play is okay, but more than a small amount of yaw is not. Yaw is where the compensator wobbles AGAINST the threads, i.e. up and down or side to side--not screwing or unscrewing. A lot of yaw indicates that the compensator's threaded end is just too big for the rifle's threads, or has the wrong threads for what the rifle has. Most compensators will have a tiny amount of yaw wobble and varying degrees of rotational play. You will have to be the judge if the wobble is excessive enough to be "unsafe" or if you can correct the wobble by hand-fitting the compensator to fit tighter. BUT BEWARE: a compensator with excessive yaw will misalign with the bore even if it screws down tighly as it locks in place. Excessive yaw wobble will simply cause the comp to screw down tightly at an angle. That is why it is critical to make sure the yaw wobble is not excessive. You must be the final judge.

You can sort of make an assessment of excessive yaw wobble by noting the side to side or up and down movement of the comp with the comp screwed onto the rifle. Make sure you unload the rifle before doing this. A rule of thumb is that the yaw wobble is excessive if, upon looking down into the muzzle of the rifle with the compensator screwed on, you can "wiggle" the comp from side to side or up and down and you can see the comp cover part of the muzzle's crown. If you can move the comp side to side or up and down (not screwing or unscrewing) and still see all of the muzzle crown through the comp's muzzle, then chances are the yaw wobble is not excessive. This is an inexact method, and you will have to use some common sense.

You could also dowel the barrel with a dowel the size of your bullet. Place the dowel in the rifle's muzzle and install the compensator, then note if the comp can be wiggled enough side to side or up and down such that any part of the inside of the comp touches the dowel. Since the bore size of most comps is larger than the bore size of the barrel, if the inside of the comp can be wobbled enough to touch the dowel, chances are the bullet will hit the inside of the comp as it exits the compensator.

Assuming the amount of yaw is not excessive, the only thing you need to do any hand-fitting for is to eliminate the rotational play. If the comp screws down tightly against the front sight base, a small amount of yaw will automatically go away.

It might seem contradictory to file on the butt-end of a loose compensator to make it fit tighter, but the problem is usually one of where the comp "bottoms out".

A loose comp is one that, as you screw it on, "bottoms out" somewhere other than right at the locking detent plunger.

Your problem is that your compensator does not "bottom out" just as the detent plunger locks it in place.

What you need to do is file the threaded end of the compensator so that it rotates further down onto the front sight base until it "bottoms out" where it's supposed to.

Looking down at your muzzle, screw the compensator all the way down, going past the final locking position until it "bottoms out" against the front sight base. If the comp bottoms out on the INSIDE before it even reaches the front sight base, go no further. That brake will never properly fit that rifle.

There are basically two types of threads on AK compensators: 14x1mm left hand thread (AK47) or 24mmx1.5mm right hand thread (AK74). The Romanian AK74 type is said to be 22mm, and usually requires you use compensators specifically made for Romanian rifles.

Now, assuming it's a left-hand thread, it turns in the counterclockwise direction. The ideal place for it to "bottom out" is between the 3 o-clock and 12 o-clock positions. For a right hand thread, the ideal is for it to bottom out between the 9 and 12 o'clock positions. If it bottoms out either too much before this, or just barely clears the locking plunger before bottoming out, then you will have a LOT of filing to do. I would suggest in that case you buy a couple of extras and hope that one bottoms out at a position as close as possible BEFORE reaching the locking plunger.

Now, if you have one that does bottom out fairly close to reaching the locking plunger, do this. Lay a flat file (coarse thread) on a table, and in A SWIRLING MOTION file the bottom of the compensator. I say to use a swirling motion so it will hone evenly. Check your work often (test fit), and when the compensator appears to bottom out just before the slot on the compensator reaches the detent plunger--STOP FILING."


With a pair of rubber gloves on, you MAY be able to tighten it the rest of the way so that it just barely clears the plunger. If you are able to do this, the compensator should remain tight except for the normal "loosening" that will happen with use. The idea is to file only until you can tighten it down the rest of the way with a little elbow grease such that it BARELY has the clearance to lock in place.

If not, SWITCH TO A FINE-TOOTHED FILE AND DO YOUR HONING A LOT MORE CAREFULLY, WITH MORE FREQUENT TEST-FITTING. Do this until you can just BARELY tighten the compensator until it clears the plunger.

Just keep filing, test-fitting, and the like until you can BARELY tighten it past the plunger with rubber gloves and a little effort. You should also realize that excessive removal of the compensator for cleaning will loosen the comp a bit over time.

I probably should add: CHECK FOR ALIGNMENT OF THE COMPENSATOR'S BORE WITH THE RIFLE'S MUZZLE WHEN YOU'RE DONE.

I had a recent issue with an AK-74 type brake where it "wobbled" and the bullet hit the sides of the brake as it exited the barrel. Because any compensator with the 24mmx1.5mm threads is of a larger diameter and thinner material, the potential is greater to accidentally file one side further than the other. Doing this may cause the bore hole to be misaligned with the muzzle. This is very dangerous. The danger is less with the 14x1mm compensators because the diameter of the area you are filing is smaller, but it still can be filed unevenly.

What I suggest is that no matter what type of compensator you are hand-fitting, that you test how evenly you've filed the threaded end. If you verify that the compensator is "level," in my opinion this will theoretically help make sure the bore hole in the compensator is parallel to the muzzle on the rifle after all your hand fitting. The slant comp is hard to test for levelness since there isn't really a place to put a level on the comp, but you should be able to notice any gross misalignment. This should be easy to do with a slant comp: there isn't much material in front of the bore. Just make sure the bullet can exit the comp without touching it. Once again, doweling the barrel with the compensator in place should tell you if there is an alignment problem.

To use a level to test your compensator's "even-ness", first you test how level your table is with a small hand-held torpedo level (you know, the kind with the air bubble in the little tube of fluid). Once you know your table is level, place the muzzle compensator muzzle up/threads down on the table and check how level the compensator is. If it's level, the bore hole should be lined up properly with the muzzle once you install it (assuming the hole was straight in the first place). If I were you, I would still verify this by doweling the barrel with the comp in place, though.

Always err on the side of safety when you test fire the compensator for the first time. I suggest you clamp the rifle in a non-marring benchrest jig and pull the trigger from behind cover with a string. Make sure your "cover" is thick enough to absorb fragments. Do this for several shots so you can examine the muzzle brake for evidence of "gouging" where the bullet is hitting it. I know this sounds like a pain in the rear, but should your compensator's bore be misaligned with the muzzle, the results of firing could destroy the brake, damage the gun, or worse.

Once you have fired several rounds and you are satisfied that the compensator is properly fitted--you're done!

(Note: none of this tutorial should be assumed to be absolutely safe even if followed exactly. You still must use your common sense and follow all safety procedures for testing the compensator before you assume that it has been fitted properly).



UPDATE: I cannot emphasize how important it is to STOP FILING when the detent slot just starts getting close to the plunger. Often times, if you put on a set of good gloves to give your hands extra grip, you can torque that sucker into place with some effort even when it looks like you're ALMOST THERE with the filing. I have fitted four compensators to different rifles, now, and I can tell you that the tightest and best fitting ones have left my fingers blistered (literally) from all the hard-torquing of screwing and unscrewing of the compensator by hand during test-fitting. It's worth it!

Because the AK compensator doesn't rely on spring tension or peel washers or anything to keep it tight, the only choice is to really make it just BARELY want to lock in place. Do not use tools: Hand pressure ONLY, please!

My best effort has now had over 1,000 rounds through it, and the detent groove in the slant brake still rests tightly against the plunger!

Good luck!
 

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Thank you Professor Zackerly. I've never put one on but I feel armed and ready now. Is this what gunsmiths call timing?
 

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Thanks, ZZ, for bringing this over to this forum. Hopefully, the moderators will see fit to give it "Sticky" status so that it doesn't get buried in the forum's bowels over a period of time as it has over on the K-Var forum.

My post over there on 11/28/05..........

"Just wanted to take a moment to post an open "Thank You" to Zane Zackerly for his assistance and for composing "How To Make Your Compensator Fit For Dummies". biggrin.gif
Truth be known, I didn't spend any more than 1/2 hour on the routine of file, test fit, file, test fit, file, test fit. I'd guess that probably half of that time was spent screwing and unscrewing that rascal.

As others pointed out, apparently some wobble is closer to the norm since I have looked at several AK type weapons in the past couple of weeks and ALL of them had some play in them."


Somewhere else along the line, I think that I also referred to it as a "mini-thesis". :smile:

It's "how-to" answers like this one provided by ZZ that give us newbies the opportunity to learn a lot from the "been there, done that" folks.

Thanks to all of you..............
 

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I fit mine by laying it down on a flat file which was larger than the diameter of the base of the brake and moving the brake across the file so I couldn't file it unevenly.
 

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Discussion Starter #5
ACMcom said:
I fit mine by laying it down on a flat file which was larger than the diameter of the base of the brake and moving the brake across the file so I couldn't file it unevenly.

It IS still possible to file it unevenly. The amount of "bear down" hand force that you use determines how much you file, and if you don't use the same amount of hand pressure all the time, you can still file it unevenly. I use either a swirling motion, or I count strokes: one, two, three, four, five, then turn the brake 1/4 turn. One, two, three, four, five, then turn the brake 1/4 turn. Keep doing that and make sure to go all the way around. My file is a lot larger than the brake's base, and I still managed to ruin one before I got the hang of it.

Judge is right: screwing and unscrewing and trying to torque it on the rest of the way with your hand really does take as much time and effort as filing.

There's an art to this. I have two installed on rifles right now: one has actually developed some play, although a lot less than an "out of the box" slant brake. The other is just as tight as the day I finished it. Both guns have had hundreds of rounds put through them since the hand-fitting.
 

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ZZ,
Wish I had seen this prior to my posts of the 15th elsewhere in this forum. I feel like I will know what to do after I get the muzzle brake that I have on order for my incoming SA M7 A1 after reading what you have posted here.
Thanks for such an informative post !! :smile:
 

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Discussion Starter #7
THUNDERKISS said:
ZZ,
Wish I had seen this prior to my posts of the 15th elsewhere in this forum. I feel like I will know what to do after I get the muzzle brake that I have on order for my incoming SA M7 A1 after reading what you have posted here.
Thanks for such an informative post !! :smile:
No problem. Your 24mm muzzle attachment will be much thinner material than one made for 14mm, so it will be easier to file too much too soon.

The good news is: I've found that most of the time the 24mm attacments naturally fit better and with less wobble as they come.
 

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Well, there's good news. Perhaps I'll be real fortunate and get a nice fit off of the one that I ordered from KVAR. It's an Arsenal manufacture AK-74 style brake with 24 x 1.5mm threads so I think that I'll be good to go.

Glad you were there to offer all the advice, ZZ. Don't know what I woulda done with out you, man. Thanks. :smile:
 

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Discussion Starter #9
THUNDERKISS said:
Well, there's good news. Perhaps I'll be real fortunate and get a nice fit off of the one that I ordered from KVAR. It's an Arsenal manufacture AK-74 style brake with 24 x 1.5mm threads so I think that I'll be good to go.

Glad you were there to offer all the advice, ZZ. Don't know what I woulda done with out you, man. Thanks. :smile:
DANGER DANGER DANGER




Beware of that one, Thunderkiss! I already called them and the center hole size for the AK74 brake IS NOT I REPEAT NOT big enough for 7.62x39!

Get the one from Krebs instead!

http://www.krebscustom.com/CustomParts.html

Just MAKE SURE you ask for the one for thirty caliber!

Mine didn't need any hand-fitting, either!
 

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Thanks again, ZZ !! I cancelled my order with KVAR as soon as I got your PM and of course have checked into the link that you have above.

Thanks for lookin' out for me :hail: , ZZ, and KCI is my first call tomorrow a.m. I really wanna keep this Arsenal lookin' as "bulgy" as possible and I am certain that KCI makes a great product.

I'll keep you up to speed on how it turns out.
 

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ZZ,

Made the call to KCI (as you suggested) today for that AK74 style brake threaded 24x1.5mm r.h.

And of course, I made sure that it was calibered for 7.62. :grin:

Should be in by Tuesday at the latest.

Thanks again, ZZ.
 

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Discussion Starter #13
THUNDERKISS said:
ZZ,

Made the call to KCI (as you suggested) today for that AK74 style brake threaded 24x1.5mm r.h.

And of course, I made sure that it was calibered for 7.62. :grin:

Should be in by Tuesday at the latest.

Thanks again, ZZ.
Anytime.
 
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