View Full Version : Indexing a muzzle brake with shims
SpyderMan2k4
06-03-12, 01:11
I just got a Battle Comp 2.0 for my latest build. Other builds I've just used a crush washer and it was a piece of cake. I've tried different combinations of different thickness shims and I cannot get it to index exactly. the closest I can get is being a alittle off one way or another.
Does it have to be indexed 100% perfectly to get the best performance, or will I get the same performance even if it's off a little one way or another? If it has to be 100%, how does one get there if the shims don't allow it? Thanks!
(in case anyone is wondering, the barrel I'm installing it on is a BCM)
I have only installed the 1.0, and not the 2.0. I would look at trying to get an additional shim kit to give you more options.
Are you usng this with a suppressor? Can you not use a crush washer with the 2.0?
I just got a Battle Comp 2.0 for my latest build. Other builds I've just used a crush washer and it was a piece of cake. I've tried different combinations of different thickness shims and I cannot get it to index exactly. the closest I can get is being a alittle off one way or another.
Does it have to be indexed 100% perfectly to get the best performance, or will I get the same performance even if it's off a little one way or another? If it has to be 100%, how does one get there if the shims don't allow it? Thanks!
(in case anyone is wondering, the barrel I'm installing it on is a BCM)
SpyderMan2k4
06-03-12, 06:08
I dont currently have a suppressor, though in the near future id like to get into the nfa game and id prefer to leave the option open. That being said, if i cant get it timed right with shims, a crush washer it is.
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PWS has a pretty comprehensive shim kit (http://primaryweapons.com/store/pc/viewPrd.asp?idproduct=109&idcategory=37) with a wide variety of thicknesses. As to alignment, I'm not sure that micrometer-like accuracy for clocking the thing is that important.
If you're not immediately going to use it with a suppressor, I guess I'd go ahead and use a crush washer and re-install with shims when you finally get the suppressor, if and when.
An Undocumented Worker
06-03-12, 20:13
If you are really OCD about getting the BC 2.0 timed up perfectly with the shims provided, and don't want to purchase any other parts or shims etc, you need a sharpening stone. Water stone, wet stone, diamond hone, it doesn't matter so long as it is flat and decently sized.
Take the big shim and hone it down a bit on the stone by applying pressure to the shim with your index finger and moving it across the stone in a circular motion. Do this while testing for fit untill you can get a combination of the big shim and little shims that will clock up with the proper torque.
Only try this if you are really OCD about it, because it will take while and a bunch of removal and reinstallation.
My first (and only) experience installing a muzzle device was with a BC 2.0. I used the shim kit that came with it and finally managed to get it timed right, but it was a huge PITA IMO. Now I'm getting ready to change out my handguard so it has to be removed (barrel nut has to be changed). I'm never going to get a Gemtech Halo so when I reinstall it I'm just going to use a crush washer. I think that's currently the only suppressor on the market that works with the 2.0 so unless you plan to get one I wouldn't worry about the shim kit.
Much easier to just get a peel washer. Heat it with a torch or one of your burners if you have a gas stove. It'll time much faster and easier.
Much easier to just get a peel washer. Heat it with a torch or one of your burners if you have a gas stove. It'll time much faster and easier.
What he said....
McMaster Part No. 90902A223 (http://www.mcmaster.com/#catalog/118/3247/=htp8h1)
SpyderMan2k4
06-04-12, 00:21
Thanks for all the replies! I ended up just using a crush washer for now. If the time comes that i want a halo for it ill probably get a more extensive shim kit. Until then im not gonna worry about it anymore. Thanks again
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Thanks for all the replies! I ended up just using a crush washer for now. If the time comes that i want a halo for it ill probably get a more extensive shim kit. Until then im not gonna worry about it anymore. Thanks again
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That's what I did with my AAC Brakeout .....no issues
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Wormydog1724
06-07-12, 17:34
I've always heard not to use a crush washer with a suppressor mount. I assume thats if you actually have a suppressor and use it with that mount. I've always used shim kits for my BC 2.0's (even though I don't have a suppressor for them) and all of my AAC SPR/M4 mounts (I do have the SPR/M4 can).
While timing is a concern with a suppressor adaptor, I am generally more focused on the amount of torque put on the barrel (less is more kind of thing). So I use washers with most every FH, MB, etc so that I get just enough torque to keep it in place.
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Wormydog1724
06-07-12, 18:49
Now I want to learn. Grant forgive but I'm about to ask a few questions and they may be silly but I'm really wanting to know (ie I'm being genuine)
When you say 'washer' in the previous post, you mean crush washer?
Do you use a crush washer even for suppressor mounts when a can will be used?
Why 'less is more' on the tightness of a brake/comp like the BC? Does too much affect POI? (I know it will change when changing muzzle devices, but will it not stay consistent with torque or too much?)
I assume that less isn't more when using a suppressor mount? A suppressor mount coming loose while shooting with the can could be very very bad.
If you don't want to answer them all it's ok. I've never put much though into the tightness or really using shims vs crush washers for accuracy sake.
Thanks.
Now I want to learn. Grant forgive but I'm about to ask a few questions and they may be silly but I'm really wanting to know (ie I'm being genuine)
When you say 'washer' in the previous post, you mean crush washer?
Do you use a crush washer even for suppressor mounts when a can will be used?
Sorry, poor wording (was posting from a smart phone and in a hurry). I should have said shims.
Lets say that we are installing an A2 FH. If the crush washer does not get it close enough, I will shim it to get better timing and less pressure on the barrel. I do not use crush washers with adaptors (unless the manufacturer calls for it).
Why 'less is more' on the tightness of a brake/comp like the BC? Does too much affect POI? (I know it will change when changing muzzle devices, but will it not stay consistent with torque or too much?)
I assume that less isn't more when using a suppressor mount? A suppressor mount coming loose while shooting with the can could be very very bad.
The more torque on the barrel usually means less accuracy.
Suppressor adaptors should always be degreased and then installed using rocksett. This allows you to properly time them without using more torque than is needed.
If you don't want to answer them all it's ok. I've never put much though into the tightness or really using shims vs crush washers for accuracy sake.
Thanks.
The USA did a test awhile ago in regards to the SE Vortex FH. They found that guns with it had improved accuracy. Why? They are installed hand tight.
IMHO, too much torque on the end of the barrel does not help accuracy in any way.
YMMV.
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The USAMU Custom Gun Shop found high torque causes the muzzle to "Trumpet" and is detrimental to accuracy.
The USAMU Custom Gun Shop found high torque causes the muzzle to "Trumpet" and is detrimental to accuracy.
Trumpet? Now there is a word I have not heard in combo with a firearm. Thanks for the info!
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A little off topic, so forgive me...
I've always wondered if it is difficult to remove a suppressor adapter or other muzzle devices that have been installed using Rocksett? Searching this topic reveals different answers; needing to soak it overnight or just using some force because it had the same holding strength as blue loctite but with a higher melting temperature.
A little off topic, so forgive me...
I've always wondered if it is difficult to remove a suppressor adapter or other muzzle devices that have been installed using Rocksett? Searching this topic reveals different answers; needing to soak it overnight or just using some force because it had the same holding strength as blue loctite but with a higher melting temperature.
Normally, force breaks them.
C4
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