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Fieldcraft Perimeter Tripwire Installation

Slo cat

VHPA đại úy
Full Member
Minuteman
  • Nov 5, 2011
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    Corner of "Walk" and "Don't Walk"
    I recently bought some tripwire perimeter alarms made from modified M228 grenade fuse assemblies. These are armed with common 209 shotgun primers. When the pin or cotter pin is pulled, a spring loaded striker strikes the primer. The sound is comparable to a pistol shot.

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    Every summer I have bears climb up on my deck (8-11 feet above ground) even though we bring in bird feeders every night. And they usually cause some damage to Mrs. Slo cat's plants.

    Here are two pics of how I trip-wired my deck for bear. I placed the grenade fuse assembly where it could be easily reloaded. I strung the trip-wire about six inches away from the outside of the deck rail where it is not likely to be disturbed except for bear. I used wheels to string the trip wire at each corner of the deck as in the second pic. The trip wire extends all the way around the deck, about 45 feet, where I placed a second grenade fuse assembly. One other thing. I tested the force needed to pull the cotter pin out of the fuse assembly with my trigger test gauge. It takes 4 lbs. of pull. Since there are many birds and squirrels on my deck, I wanted a heavy enough resistance on the string to keep false alarms to a minimum. I also drilled a hole in the center of the assembly to make it easier to nail it to something solid.

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    This is what I use for Early Warning in the field for work. Its a Victor rat trap with three 3/8 inch holes drilled out (marked in red). The whole at the bottom will have a loop of 550 cord pulled through (yellow), to hold a chem-light(black). The chem-light can be IR or colored depending on the situation and your NV capabilities. You then attach the trap around a tree at eye height from your position and run a trip wire (lime green) from the trigger across the Anticipated Avenue of Approach. When the trap is set it will sound similar to a breaking stick but give the observer a heads up as to which direction the enemy is moving in from.

    I didn't feel like unpacking my field gear to make the mock up so please excuse my crude paint hand-jam
     

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    I already know where to get them, just curious if it's worth possible legal issues haha
    From my law enforcement perspective (at least as it pertains to California Law), as long as its not a trap to cause injury to anyone, then you should be good.

    That doesn't mean it wouldn't garner the attention of LE if a neighbor in a urban/suburb AO were to call.....

    In more rural areas, I dont think that it would be an issue.
     
    Some of my neighbors (including myself) enjoy occasional target practice in their back yards (or off their decks). So a single report from my bear alarm will not be noticed by them. Just me and Mrs. Slo cat. I also have a Remington 11-87 loaded with rubber buck shot handy inside near the door to the deck. But have not had the opportunity to see how effective the rubber buck shot is on discouraging bears.
     
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    There is nothing illegal about these. They’re only a “noise maker” and unless you try putting one between your teeth they’re not harmful.
    We just used these right before the election.
    We have the corner lot on the entry to our sub division and the main road so the neighbor asked if she could put a big Trump flag up in our tree line along the main road. I went out with my 14 year old son and ran two of these along the outer edge because I was sure someone would try to fuck with it. Sure enough heard one go off about 11pm one night. Needless to say it worked and scared them off and we could clearly hear it inside the house, over the sound of the TV.
     
    Do these work at keeping the bears at bay? Ive been wanting to get a couple to take camping. I figured they would be a decent alarm if a bear wanders into camp or around our tent. I also figured they would scare the shit out of me if they went off at 2 am. :LOL: I just wasnt sure if they would scare a bear off or if a bear would be more interested in human burritos with a side of weiner dog.
     
    Do these work at keeping the bears at bay?

    Polar Bear = NO
    Kodiak Bear = NO
    Brown Bear = NO
    Grizzly Bear = NO
    American Black Bear = YES (this species is generally very warry of human contact)
    Panda Bear = Maybe
    Teddy Bear = Sometimes
    Australian Drop Bear = NO
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    If the alarm does not frighten the black bear away, but I can test my rubber buckshot on it, then it is still a win for me. ;)
     
    Last edited:
    Polar Bear = NO
    Kodiak Bear = NO
    Brown Bear = NO
    Grizzly Bear = NO
    American Black Bear = YES (this species is generally very warry of human contact)
    Panda Bear = Maybe
    Teddy Bear = Sometimes
    Australian Drop Bear = NO

    If the alarm does not frighten the black bear away, but I can test my rubber buckshot on it, then it is still a win for me. ;)
    How about Sloth Bears??


    Yeah i am in Grizzly and black bear country.. maybe ill get some and tinker with it for other uses..
     
    This is what I use for Early Warning in the field for work. Its a Victor rat trap with three 3/8 inch holes drilled out (marked in red). The whole at the bottom will have a loop of 550 cord pulled through (yellow), to hold a chem-light(black). The chem-light can be IR or colored depending on the situation and your NV capabilities. You then attach the trap around a tree at eye height from your position and run a trip wire (lime green) from the trigger across the Anticipated Avenue of Approach. When the trap is set it will sound similar to a breaking stick but give the observer a heads up as to which direction the enemy is moving in from.

    I didn't feel like unpacking my field gear to make the mock up so please excuse my crude paint hand-jam

    The Trip Wire missing the M18 is way more tactical , and where can you buy that ? Asking for a friend.
     
    There's also the:
    Koala Bear
    Kermode Bear

    The former I'm told are best deep-fried, while the latter most folks have never heard of. Kinda rare, but prevalent in one particular part of B.C.

    Then too, you can't forget:

    Huggy Bear, but for that you need a pimp-hat with feather.
     
    Has a bear tested it out yet?

    seems like a good idea but my concern would be the trip wire being towards the top of the rail as bears usually climb when spooked and they’re already going to be close to the top when that goes off.
    Wouldn’t want a pissed off bear stuck on my deck! Maybe having the wire below the deck level would work better as a deterrent? Just food for thought , but neat system.

    & I feel your pain with the bears. We too have “bear problems” so aside from removing the bird feeders I had hung one feeder off the eve of the house thinking “ let’s see them get that one! “ and sure enough i now have bear claw marks all up and down my house and we never saw that feeder again.
     
    Some of my neighbors (including myself) enjoy occasional target practice in their back yards (or off their decks). So a single report from my bear alarm will not be noticed by them. Just me and Mrs. Slo cat. I also have a Remington 11-87 loaded with rubber buck shot handy inside near the door to the deck. But have not had the opportunity to see how effective the rubber buck shot is on discouraging bears.
    Less than buckshot.
     
    seems like a good idea but my concern would be the trip wire being towards the top of the rail as bears usually climb when spooked and they’re already going to be close to the top when that goes off.
    Yes, a trip wire at the top of the rail would be too high, and then squirrels might trip it. If you look carefully at the photos, you can see that the trip wire is only about 8" above the floor of the deck, where a bear would trip it on it's way up.