MUZZLE BREAK SUPRESSOR HELP

Discussion in 'Firearms' started by irayone, Jul 2, 2012.


  1. irayone

    irayone Monkey+

    I have a Savage Arms FCR-10- SR The end unscrews to provide for a supressor. I have the supressor and a washer. Is there any special way to instal it???? Ft Lbs etc. Or does it just screw on that easy?
     
  2. BTPost

    BTPost Old Fart Snow Monkey Moderator

    I suspect it screws on, slightly tighter than "finger tight".... You do not want it to unscrew, while you humping thru the bush.... You also want to be able to take it off, in a pinch..... ..... YMMV.....
     
  3. irayone

    irayone Monkey+

    Thanks I didn't know if it was that simple or if I should use "Lock Tight" ???
     
  4. Hispeedal2

    Hispeedal2 Nay Sayer

    If you are talking about a flash suppressor and you have a crush washer, you need to hand tighten until it stops. Slap a wrench on there and torque until it starts crushing, back it off a bit, start crushing, back it off, etc...... until you index the flash hider correctly.

    The cup of the crush washer should face the flash hider... if that makes sense.

    If you hand tighten it, you may be looking for it in the grass after a handful of shots. If you have peel washers, hit me up and I will send torque values.
     
  5. tacmotusn

    tacmotusn Mosquito Sailor

    Its all about percent of threads. A machinist could explain better than I can, but 75 to 80% thread is normal for being able to spin a nut on a bolt with fingers alone. Only in special applications are threads machined greater than that 75 to 80% standard, and a wrench is required to assemble. Very little chance of such an assembly backing off exists in normal operation. There are some current regulations with regard to manditory manufacturer safegards for this situation for threaded barrels and accessories where they are pinned or soldered or otherwise secured in place. I would advise yes, use the strongest Locktight (it comes in different ratings) you can obtain.
     
  6. tacmotusn

    tacmotusn Mosquito Sailor

    Hispeedal2's info sounds more on point in this application, than mine. jus sayin
     
  7. Tikka

    Tikka Monkey+++

    Excellent advice as proper torquing is not as easy as believed.

    From Army TM 9-1005-319-23&P:
    Torque compensator (12) to 15-20 ft-lb (20-27 N-m) using combination wrench (10) and torque wrench. T orque is measured when both wrenches are used together. Some portion of the openIng of the third or middle slot must be straight up (align with the front sight post) (12.1) at proper torque level. Thin sections of the peel washer may be removed or added as required. Save unused sections.

    http://www.ar15armory.com/manuals/TM9-1005-319-23.pdf

    A peel washer is a bunch of thin washers laminated together, you can use a razor blade to pry in between the layers to remove one. Install the flash suppressor by hand and note how far the timing is off. Then remove it and peel a layer off; trial and error works well. ;)

    One of the reasons for replacing the M16's three prong was using it as a wire cutter to open cases of C-rations loosened it. Once loosened tightening securely was next to impossible with the available tools.
     
  8. irayone

    irayone Monkey+

    Thanks...The washer...there is a flat end and a rounded end. I would assume the flat end sits on the barrel as it sits flush. And the round end sits on the supressor...Sorry I just want to do this right the first time. Does the round end need to flatten to sit flush on the round end?
     
  9. Hispeedal2

    Hispeedal2 Nay Sayer

    The "wider" end goes against the flash hider. The reason is that you get more surface area in contact with the flash hider (since it generally has more shoulder than most barrels). I think in your terminology, the round end goes against the barrel.

    I hope I haven't confused you.

    Here is a great video- http://www.brownells.com/.aspx/lid=11441/learn/
    A note on the video- the preferred method of torquing anything on the barrel is to use a barrel clamp, not the receiver as shown in the video. In your case, a couple wooden V blocks in a vice will work quite nicely... you don't have to kill a crush washer to get it it torqued correctly.
     
  10. irayone

    irayone Monkey+

    Thanks...I had it wrong>>>>The crush washer was backwards. I have corrected the problem.
     
  11. ghrit

    ghrit Ambulatory anachronism Administrator Founding Member

    Edumacate an olde phart. Are these washers actually crush washers that deform and don't return to shape, or are they actually like belleville springs that exert a force and will return to original shape when the torque is removed?
     
  12. Tikka

    Tikka Monkey+++

    Belleville washers apply axial force. In this application, it would need be keyed to the barrel and to the flash suppressor to prevent rotation. Although there are ways, those designs require more landscape and machined features; so it really isn't a good application for a Belleville.

    Peel or crush washers are a bunch of thin plates laminated together by a thin compressible compound between them. Laminations can be removed to shorten the height. A flash suppressor threads on and it needs to be correctly timed. A variable length spacer such as the crush washer is the perfect solution. The trick is to hit the torque target at the same moment the groove indexes correctly.
     
  13. Hispeedal2

    Hispeedal2 Nay Sayer

    They flatten/crush. 90% of the time they are one time use. To achieve the proper level of torque, not much crush is needed at all. Hence the crush, back it off, crush back it off, etc until it indexes and torques. I never check the torque with a torque wrench on FHs. I can feel if there is enough.

    Crush washers replaced peel washers. Some newer breaks have shim sets that come with the device. They work similar to peel washers except there is nothing to peel- you use a combination of different sized shims. Typically they have a chart that tells you what combination to use in shim(s) based on where it indexes when finger tightened.
     
  14. ghrit

    ghrit Ambulatory anachronism Administrator Founding Member

    OK, that's a bit clearer.

    I've used belleville springs with nothing in the way of indexing other than torque values, basically why I asked. The axial force essentially sets the friction high enough to prevent turning.
    I've used crush washers in a number of applications, and as noted they are one time use because once crushed, they do not rebound to allow the same torque to be applied at an index as the first time.
    Never have used peel washers, but it seems to me that they are like shims in that they allow the correct torque application to get at the index marks as many times as might be needed, if the torque is within the elastic limits of the washer material. (Hard to believe, but you can over torque washer stacks and deform them. NFG when that happens.)

    One of the things that got me looking into this was from a LONG time back when I was told by someone who knew, that it is NOT the lugs that keep the wheel turning, it's the friction between the wheel and hub. It is the torque applied to the lug nuts that puts the squeeze on the interface surfaces to keep the friction high enough. Take it to the bank, it's fact. I didn't believe it at the time, made no sense. Does now.
     
  15. irayone

    irayone Monkey+

    Please give the deffinition of "indexing"
     
  16. Hispeedal2

    Hispeedal2 Nay Sayer

    Indexing- Is the top pointed up?

    Some FH have a top and bottom. Some don't.

    Index- a pointer or indicator in a scientific instrument.
     
  17. Tikka

    Tikka Monkey+++

    "15. Torque compensator (12) to 15-20 ft-lb (20-27 N-m) using combination wrench (10) and torque wrench. Torque is measured when both wrenches are used together. Some portion of
    the openIng of the third or middle slot must be straight up (align with the front sight post) (12.1) at proper torque level. Thin sections of the peel washer may be removed or added as required.
    Save unused sections."
    http://www.ar15armory.com/manuals/TM9-1005-319-23.pdf

    Page 3-44 Change 4

    The TM (Technical Manual) is for the 3 prong or birdcage compensator. YMMV, with after market compensators.
     
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