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Thread: Butt stock filler/ kimber 8400 montana question

  1. #1
    Member honeybadger's Avatar
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    Default Butt stock filler/ kimber 8400 montana question

    I am installing a gracoil recoil buttplate on my kimber 8400 montana, chambered in 300WM, due to some issues and concerns with my scope. I lapped the rings, tightened everything to specs from IOR and Kimber regarding the base and rings. I also put locktite on all of the screws involved in mounting the scope. I have put a douglas premium barrel with drilled in muzzle break to add weight and reduce recoil already. Additionally I re-glass bedded the stock so everything is tight with the barrel properly free floating and the recoil lug tight fitting. The rifle will drive tacks (1/2" groups at 100yds) for about 100 rnds then innevitably one portion of the scope mounting system will vibrate loose, (with the most recent incident being the base itself). An additional measure I am taking is installing a gracoil recoil reducing butt plate (should arrive today). I noticed in taking the factory recoil pad off that the buttstock itself is hollow on the inside. I am not familiar with what the stock is comprised of, but it almost seems as though it is a rigid plastic as opposed to a composite resin or fiberglass compound. The walls in the buttstock are about 3/8" thick. The buttstock is filled with a rigid, and fragile, styrofoam. It does have tapped guideholes for attaching a butt plate, however with the gracoil buttplate having an internal piston it needs firm bracing within the butt stock. Here are my questions:

    1. What compound would you use to fill the buttstock? ( I am currently planning on using an industrial two part epoxy with fiberglass fibers mixed in)

    2. What in your experience is the best way to remove the styrofoam from inside the buttstock? (I plan on scraping it out, then prepping the inside with an MEK wash or mineral spirits)

    3. What additional steps would you take along with installing this butt plate to reduce recoil? My main concern is no longer weight, (considering the time and money I have invested in this rifle), its reliability. I have slowly brought this rifle from the POS I purchased to fine tuned, but this issue with the scope is driving me insane. (No i do not want to replace the stock, have a Mac A5 on my 700 and I know this factory stock is flimsy from what I have seen, but the look and feel has grown on me)

    In closing do not buy a Kimber 8400 Montana unless you want to put up with the frustration and heartache I have had to endure for about 8 months now. On the other hand it has been a nice little project. Thanks for your input!

    Zach

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    I'm just speaking to the fill. As for the foam, get out what you can, get it as clean as you can. about it.

    For the fill, go to West Marine and pick up a quart system of the west sytems epoxy, the 105 resin. I also like using the 206 slower hardener vs the 205. More working time. Kind of expensive, but simply awsome all around epoxy for everything. Get the pumps, only good way to dispense it

    For the fill, get the microbaloons. I "think" its the 108 filler. It is tan in color. I would do it it 2-3 pours, to avoid getting too hot. If you were to leave a cup of this to harden it would melt through most plastic cups. I'd do 4-5 "pumps" at a time

    Anyway, mix in filler until you can still pour it. It will result in 3x to 4x additional volume. The hardened epoxy can me drilled, filed, etc. Kind of like a super hard foam, would get you what you want without undo weight. I've made a few rifle stocks and used this to fill.

    Also, are you using the red bottled, blue locktite on screws, its the removable stuff. I shoot a 375 and a 300wm, never has any issues with things shooting loose

  3. #3
    Member honeybadger's Avatar
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    Finished filling the butt stock. After a bit of research I found that the stock is made of a carbon-kevlar composite while the foam is more than likely a phenol based foam as it did not react to acetone, MEK, xylene, mineral spirits, lacquer thinner, or paint thinner, (additionally when I took a piece to burn it, it did not smoke much or melt, and it put itself out when the flame was removed). Unfortunately I did not have any caustic soda on hand. I scraped it out to the best of my ability and vacuumed/brushed it out afterward.

    I accidentally bought the fast hardener, and opted to go with the micro fibers rather than the balloons for the filler. I also added a black pigment agent to it in case I got a little on the edge of the butt plate. It mixed well with the pumps. I filled it in two 'ten pump' pours due to the fact I had the fast acting hardener, (didnt want to mess around with it more than I had too). The epoxy went in nicely, and did rise to an extremely hot temperature for about 45 minutes as the epoxy began to set.

    I will file/sand the butt stock so that it is flush today. I will take pictures of the entire installation process and post them on here to let you all know how it went. I appreciate the heads up YT on the west system products, they seem to be pretty solid and I'm glad I went with them over the arcaglass that I had on hand for butt stock repairs.

    I think one issue with the scope coming loose had to do with the bases that I had on until two weeks ago. I had the two piece dovetail bases from Kimber and it looks like the rear base windage adjustment screw began stripping the side of the base as it moved little by little. I believe this gave it enough room to work the front base screws loose. I have since shelled out the money for the one piece picattiny rail mount and tactical rings to aleviate the problem. I tend to beat on my sheep rifle when I'm in the field so I can't afford to have my scope coming loose at a range. I'm sure this all might be over kill, but better safe than sorry!

    Thanks again,

    Zach

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    If the scope mounting screws begin to loosene again, you might try simple old beeswax on the threads. Non-hardening, that absorbs recoil well and does't seem to work loose. Has always worked for me, but that's just my two cents' worth . . . . .

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    Member GD Yankee's Avatar
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    Did you ever try the Talley Lightweight bases/rings? That's what I have on mine and with a little loc-tite, I've never had a problem.

    Kimber makes a great looking product, but man, most of us have had issues with them. I wish they'd read these forums and fix it.

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    And here I sit with a Kimber MT 325 that I've had since 2006 and it's a tack driver and I have not had one problem with it other than a cosmetic issue with the stock the first year (small bubble) and when I called Kimber they mailed me a new stock. It's a fantastic gun and a keeper. Talley LW's, leupold 2.5-8x36. I've used it hard packing in on sheep hunts, bouncing around on an atv, etc. and it holds zero no prob.
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    You used epoxy to fill a buttstock? That sounds expensive. I have filled two by pouring lead shot (#8) to get the weight I wanted, then squirting foam-in-a-can from the local hardware in behind the shot. Once hard, just trim it off with a knife. Worked great.
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    Member honeybadger's Avatar
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    I used west systems 105 with 206 hardener and micro balloons, worked great, more than the weight it stiffened the buttstock up. I ended up doing the same with the fire grip. Not surprisingly I found out the stock itself wasn't straight. Milled it out and re glass bedded it to give it 1/8" clearance all the way up to 2 " in front of the recoil lug. Turned out great, zeroed it this weekend. It shot nicely, can't recommend gracoil butt plate enough. Drives tacks and at 8.5 lbs it sounds like a canon but shoots like a .22. Ill post pics of it soon, not the prettiest thing in the world but I'm all smiles now.

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    Member broncoformudv's Avatar
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    So you bought a lightweight rifle and have been adding weight to it?

    As long as you are having fun working on it then have at it.

    Owned my Montana in 300 win mag since 2008 and beat the crap out of it and never had the factory rings or bases come lose. Guess I better go knock on wood or keep my fingers crossed.

  10. #10
    Member honeybadger's Avatar
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    Quote Originally Posted by Snyd View Post
    And here I sit with a Kimber MT 325 that I've had since 2006 and it's a tack driver and I have not had one problem with it other than a cosmetic issue with the stock the first year (small bubble) and when I called Kimber they mailed me a new stock. It's a fantastic gun and a keeper. Talley LW's, leupold 2.5-8x36. I've used it hard packing in on sheep hunts, bouncing around on an atv, etc. and it holds zero no prob.
    I'm glad to hear yours shoots well, consider yourself lucky, from talking to others with this rifle (both short and long action) you have that one in a hundred! Whatever I did haven't had any issues since, appreciate the input guys. I can rest easy now and focus on shooting rather than tweaking equipment...feels like a load has been lifted off my shoulders at this point.

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    Member honeybadger's Avatar
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    Wish I had the same experience! But I learned a bit from the build, had fun with it and I'm achieving the accuracy I'd like to have, added a few pounds, but gained a lot of confidence in the rifle. Shoots as well as my 700. I have been thinking about trying to find a kimber receiver and starting another build with a Krieger I got out in the garage and filling in and milling out a spare A3-5 stock I have. Love the action, can't ask for a smoother feeding action.

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    Member honeybadger's Avatar
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    photo.jpg

    here she is, not the prettiest thing but I have no complaints. Still have to find the photos of it with the butt stock chopped off and the foregrip of the stock cut out!

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    Member honeybadger's Avatar
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    photo-1.JPG

    Here's the 700 while I was bedding it, wife didn't appreciate me using the kitchen table I don't think.

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