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How to Stiffen a Flexible Forend?
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<Doc Garnett>
posted
I prefer to shoot using the sling whenever practical, but one or two of my synthetic stocked rifles have forends that bend too much for the shooting sling to be useful. Do you think that routing out a channel in the bottom of the barrel channel and filling it with, say, "Steelbed" would solve this problem? Any other ideas?
-- Doc
 
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<Kerry.S>
posted
We sometimes put a steel rod in a channel then seal it up with glass bed. Don't know exactly how much stiffer it is but it seemed to help
Kerry
 
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one of us
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I've heard of aluminum rods being glassed in to stiffen the forearm.

Keep in mind, steelbed is heavy stuff and will probably throw off the balance of the gun if you do the whole forearm...

My synthetic forearms flex, but I haven't seen any ill effects in terms of field accuracy.

 
Posts: 360 | Location: PA | Registered: 29 September 2001Reply With Quote
one of us
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My "short" answer is to use a v-8 push rod. Cut of the ends, degrease, and sand blast, and 'glass it in. Solid, hollow, or foam filled stocks present issues that you might want to noodle before proceeding.

The "long" answer, if you use a laid-up synthetic versus injected, is to have some carbon fiber mat added to your stocks (action forward) when they are manufactured.

 
Posts: 63 | Location: NW Colorado | Registered: 07 July 2001Reply With Quote
<Jordan>
posted
You did not say whether your stock was fiberglass or plastic. If it is fiberglass (not plastic), this works very, very well: dremel out the forearm for the length of the barrel channel so that the glass lay-up is exposed inside the barrel channel and all the way up on the sides of the foreend. In other words, dremel or sand or carve out all of the fill material in the forearm, leaving only the fiberglass shell clean on the inside. Rough up the interior of the shell with 100 grit paper and wipe it clean with acetone.

Cut two or three (I prefer at least three) layers of carbon fiber/graphite bi-directional weave cloth to fit the length of the barrel channel and well up onto or even past the sides (i.e., it does not hurt if the cloth sticks up above the top edges of the fore end).

Be sure and mask off the rest of the stock, or at least the fore-stock. After the cloth is cut to a decent fit (does not need to be perfect) wet out each layer of cloth well with epoxy matrix (i.e., epoxy resin and hardener) and place into the inside of the fore end. West Systems makes a good epoxy, but I think the easiest source is either Tap Plastic (if you have a local store) or www.fibreglast.com. Fibreglast also sell the carbon fiber/graphite cloth you need. Be sure and get bi-directional weave.

After you have two or three layers of cloth wet out with epoxy and properly placed into the interior of the fore-end, let the stock cure. Do not apply radiant heat of any kind!!! If you do, the carbon fiber will warp and twist your fore end all to hell. A room temperature cure (or maybe slighly elevated to perhaps 90-100 degrees (no more!!!) will give you post cure temp resistance to about 180 degrees, perhaps more depending on which epoxy you use.

After cure, use a dremel or sharp razor to trim the edge of the carbon fiber cloth which is sticking out above the barrel channel or interior of the fore end. Be careful!!! The edges of the cured carbon fiber are razor sharp. Also, do not breath the stuff if you are dremeling it (use a dust mask).

Fill in the rest of the foreend with micro-ballons and epozy or expanding foam, then float your barrel with a layer of
Devcon plastic steel (or Brownell's Acraglass, whatever) between the foam core and the barrel. You can also lay a little fiberglass on top of the foam core. This is the best way to do it and then float the barrel with the Devcon on top of that.

The carbon fiber is incredibly stiff. I have found this method far superior than say glassing in an alumimum arrow or rod, etc. The channel shape of the carbon fiber, in its cured stage, provided you have used at least three layers, is incredibly rigid. Be sure and to back at least to the recoil lug. I like to extend the cloth back past the recoil lug all the way to the magazine if possible.

Regards,

Jordan

 
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<Mike Anderson>
posted
HS precision offers a channel they will install on their stocks. It also provides for multiple swivels and very good adjustment. The swivels can slide in the channel.
 
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<allen day>
posted
The best way to deal with such an issue is to scrap that flexible stock and replace it with a top-end McMillan or Rimrock stock. These don't flex. Forend flexing is indicative of a basic material/design flaw that bandaid measures simply will not completely resolve.

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<Jordan>
posted
A couple of comments.

I don't disagree that a stock with too much forend flex is improperly designed or inadequately constructed. The problem, in my opinion, is that many sporter stocks, including McMillan sporters, have more fore-end flex than is conducive to optimal accuracy. (I cannot speak to the Rimrock because I have not seen one.) I am not saying McMillans are not fine stocks either. The salient point is that if the stock is fiberglass, the problem of too much flex can be fixed without spending $300.00 on a new stock. One is certainly free to spend the three c-notes if he wishes, but for those who lack that kind of spare change, the problem can be completely eliminated by the method I outlined above. Even epoxying in an aluminum arrow or other similar rod or fixture helps, but a U-shaped channel of carbon fibre is stiffer than just about anything from the factory on the market, at least in a sporter stock and it is easy to do.

For the person who does not want to spring for a brand new stock, the carbon fiber lay-up described above is less than a $50.00 fix and makes an interesting winter project to boot.

Regards,

Jordan

 
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Picture of D Humbarger
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Thanks Jordan I will certainly try this. I don't see why it wouldn't work on skinny wooden forarms & some Mannlichers also.

------------------
NRA Life member

 
Posts: 8346 | Location: Jennings Louisiana, Arkansas by way of Alabama by way of South Carloina by way of County Antrim Irland by way of Lanarkshire Scotland. | Registered: 02 November 2001Reply With Quote
<Jordan>
posted
Bearclaw:

It will work on any stock which epoxy resin will adhere to. This means wood and/or fiberglass (if the fiberglass is layed up with epoxy, which all the major brand fiberglass stocks are), but it won't work on plastic or injection molded stocks.

It works great on wood. What I like to do for weight savings in a wood stock is dremel out the wood in the foreend so all that remains is a relatively thin exterior wood shell, then glass in the carbon fiber cloth and fill the void with a micro-ballon epoxy paste or expanding foam. You can get quite abit of weight out of the foreend doing this and make it very, very stiff as well. It is best to go back past the recoil lug with the cloth, if you can. This means you will have to bed in a new recoil lug mortise.

Please let me know if you have any questions.


Regards,

Jordan

 
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Picture of D Humbarger
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You da man Jordy! can't wait to do this to my next wood stock. I just found an excuse for another project! Now how can I make this tax deductable?

------------------
NRA Life member

[This message has been edited by Bear Claw (edited 12-07-2001).]

 
Posts: 8346 | Location: Jennings Louisiana, Arkansas by way of Alabama by way of South Carloina by way of County Antrim Irland by way of Lanarkshire Scotland. | Registered: 02 November 2001Reply With Quote
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Picture of Paul H
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Listen to Allen!

Filling up the channel with steelbed will just make it heavy.

I have a tupperware stock on my 35 whelen ackley, don't recall if its a butler creek or ramline, but typical cheap plastic stock. To say the foreend is flexible is an understatement.

I went after the fore end with a carbide burr to roughen it up, then bedded a 1/2" od 3/8" id piece of 6066-T6 tubing, and carbon fibre tape epoxied all in nicely. It is still flexible, and will be replaced once I get around to bedding a nice piece of claro that was given to me.

 
Posts: 7213 | Location: Alaska | Registered: 27 February 2001Reply With Quote
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