Bipod broke my stock!!! Ever seen this?

pmh-usa

Well-Known Member
Joined
Jul 5, 2010
Messages
225
Location
SC
I do a good bit of modifying, overhauling, customizing, re-purposing, or what ever the hell you want to call the make-overs I do with composite stocks. When I say the term “composite” I do NOT include plastic 'tupperware' stocks in the category. Having said that, I’ve 'operated' on just about all the current makes of composite stocks out there and therefore while I certainly don’t consider myself and expert authority, I do consider myself a stockmaker of 40+ years of experience, which for years was entirely in wood. If there is way to “f-up” I’ve probably done it and even a moron with a 2-digit IQ learns from repetition. I would add that there’s been nothing more educational than building my own stocks with the exception of ‘forensically’ dissecting the work of others who were/are most-assuredly smarter than I. So again, I stress that my opinion of the situation in which you find yourself, is not expert but experienced.

First of all, the manufacturer recommended NOT to use a bipod. That stock was designed to manage recoil-related stress loads only in the action area - the forearm was not designed - and therefore not reinforced - for the stress attributable to the bipod. It was designed to handle load attributable to carrying the rifle with a sling which would never exceed the weight (8-10 lbs) of the rifle under normal use. I don't recall if you said what caliber this was, but recoil of most medium-caliber rifles would manifest itself in a totally different direction, as a sudden, microsecond impact, and most likely at least twice that amount of force.

Ultra lightweight stocks - as you have there - have a composite shell with very rigid (strong-for-its-weight) open-cell polyurethane foam - there's no aluminum chassis or rigid-composite frame (running throughout the stock) with reinforced "stations" to attach external fixtures or equipment mounts nor absorb external pinpoint-concentrated impact loads. To do what you intended would require a larger-area base that could spread that load over a larger area of the stock. This modification in itself would be a contradiction (weight penalty) of the stocks primary purpose/objective. Not sure if it would've made much difference, but you would have been better off flattening the prongs of that T-nut - as each of those was like driving a screw driver into the stock with a hammer, and being driven through the inner shell and foam started a stress fault which became catastrophic crack/break when you shot it.

IMO, given the manufacturer's warning, in warranty “legalese” your actions qualify as misuse which frees the manufacturer from any liability.

Having said that, if would like to PM me, I would be happy to discuss further with you, and see what I could do to repair your stock ‘gratis’ . . . just one shooter trying to help another.

P-man
 
Last edited:

Blacktailer

Active Member
Joined
Sep 17, 2019
Messages
40
Location
AZ
I do a good bit of modifying, overhauling, customizing, re-purposing, or what ever the hell you want to call the make-overs I do with composite stocks. When I say the term “composite” I do NOT include plastic 'tupperware' stocks in the category. Having said that, I’ve 'operated' on just about all the current makes of composite stocks out there and therefore while I certainly don’t consider myself and expert authority, I do consider myself a stockmaker of 40+ years of experience, which for years was entirely in wood. If there is way to “f-up” I’ve probably done it and even a moron with a 2-digit IQ learns from repetition. I would add that there’s been nothing more educational than building my own stocks with the exception of ‘forensically’ dissecting the work of others who were/are most-assuredly smarter than I. So again, I stress that my opinion of the situation in which you find yourself, is not expert but experienced.

First of all, the manufacturer recommended NOT to use a bipod. That stock was designed to manage recoil-related stress loads only in the action area - the forearm was not designed - and therefore not reinforced - for the stress attributable to the bipod. It was designed to handle load attributable to carrying the rifle with a sling which would never exceed the weight (8-10 lbs) of the rifle under normal use. I don't recall if you said what caliber this was, but recoil of most medium-caliber rifles would manifest itself in a totally different direction, as a sudden, microsecond impact, and most likely at least twice that amount of force.

Ultra lightweight stocks - as you have there - have a composite shell with very rigid (strong-for-its-weight) open-cell polyurethane foam - there's no aluminum chassis or rigid-composite frame (running throughout the stock) with reinforced "stations" to attach external fixtures or equipment mounts nor absorb external pinpoint-concentrated impact loads. To do what you intended would require a larger-area base that could spread that load over a larger area of the stock. This modification in itself would be a contradiction (weight penalty) of the stocks primary purpose/objective. Not sure if it would've made much difference, but you would have been better off flattening the prongs - as each of those was like driving a screw driver into the stock with a hammer, and being driven through the inner shell and foam started a stress fault which became catastrophic crack/break when you shot it.

IMO, given the manufacturer's warning, in warranty “legalese” your actions qualify as misuse which frees the manufacturer from any liability.

Having said that, if would like to PM me, I would be happy to discuss further with you, and see what I could do to repair your stock ‘gratis’ . . . just one shooter trying to help another.

P-man
P-man, you are a stand up guy. Seems to me this thing could be fixed without adding undue weight and be better than the original. Hope the OP takes you up on such a generous offer. I haven't done any stock making but it seems with a couple of aluminum bars and some epoxy, this thing could be better than new.
 

jakelly

Well-Known Member
Joined
Sep 14, 2010
Messages
406
Location
Pennsboro, WV
Run two carbon fiber rods, wrap the seam in carbon fiber, and be done. I personally would probably wrap most of the fore-end. I would for sure do a few layers in that barrel channel after I removed enough material to clearance them. Paint it yourself when you’re done.

The manufacturer’s claims are not worth addressing. Clearly Cooper thinks less of their products than many folks here do/did.
 

Farmerboy78

Well-Known Member
Joined
May 23, 2018
Messages
480
Location
Arkansas
Like above, I'd clean the foam out of the broken tip for 2" at least and the broken end of the forearm. I'd get a carbon arrow and cut it to length for 2-3 pieces. Insert them into the foam and use a liquid epoxy to fill the void.
 

nksmfamjp

Well-Known Member
Joined
Jan 5, 2004
Messages
670
I have some limited composites background....That break does not have enough fibers in it and they are breaking too short. The matrix appears to have cracked at the hole, but should have stopped at the next fiber, but instead the fibers broke(rare) or there were not enough fibers and it propagated around them.

A clean break means not enough fibers. Short fibers at the break means they designed the fibers too short and they pulled out or they broke. Either way that break should be a hairy mess with some unbreakable fibers between the 2 pieces.

I think they owe you a stock!

Im just some internet commando It seems, but go break anything fiberglass and let me know how that goes for you....
 

26Reload

Well-Known Member
Joined
Dec 25, 2016
Messages
2,323
Location
SE Idaho
Find an old fiberglass stock...cut out the section (fiberglass stock) just to the front portion where yours broke..sand to fit...expoxy or jb weld it together....just make sure both pieces are roughed up so epoxy or in weld will adhere solid....fill in any exterior gaps...touch up the paint....if you want to reinstall the rail..cut a flat bar aluminum and bed it into the fore end and redrilll your screw holes......
 
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