Do fiberglass stocks warp?

S

sgt_jamez

New member
I have noticed a recent change in how the barrel sits in the barrel channel, plus when the action screws are torqued I get bolt binding when moving fore/aft.

The details on the stock (not sure if I am supposed to omit the mfg)
F-class stock
Bedded with Marine Tex (barrel centered in the channel with wraps of electrical tape)
Painted with good quality auto paint and clear coat
Action screws torqued to 40 in/lbs as measured with a Borka ATK and Wheeler digital FAT wrench
BVSS action with a 1" straight taper bull barrel

I took the action out yesterday and did a visual inspection on the bedding. I can't see anything that would cause the action to sit skewed in the stock. The bedding is not cracked or visibly malformed, and no foreign objects or materials were found. The barrel was floated enough that a dollar bill would easily pass the entire length of the barrel channel. Now, when torqued to 40 in/lbs, the barrel makes contact with the stock and the bill won't pass.

Additionally, when the rear action screw is torqued to spec the bolt binds in it's fore/aft travel. I tested this with torque values ranging from 15-40 in/lbs in 5 in/lb increments. At 35 in/lbs, the bolt moved freely. At 40 it was bindung up. Even at 38 it would move ok, but by 40 it was sticking. This leads me to believe there is a high point somewhere that when the action screws are torqued causes the action to flex enough to cause the binding. The high point, I'm guessing is the contact point of the barrel and the stock.

This condition is new. I've only had the stock a short time, and it's only been out to the range I think 4 times. I've always torqued to 40 in/lbs and the binding was never an issue.

I put this barreled action into a factory Savage F-class stock and when torqued to 40 in/lbs the barrel sits straight in the barrel channel, and the bolt moves freely. This leads me to think the stock has an issue but I don't know what else I can do to diagnose and resolve the issue.

Any input on this situation would be greatly appreciated. I can post pics if that would help.
 
I notice you don't mention pillars anywhere in this post. If you don't have pillars installed, my guess is that the stock material has compressed and that is causing your issues.
 
sgt_jamez said:
I have noticed a recent change in how the barrel sits in the barrel channel, plus when the action screws are torqued I get bolt binding when moving fore/aft.

The details on the stock (not sure if I am supposed to omit the mfg)
F-class stock
Bedded with Marine Tex (barrel centered in the channel with wraps of electrical tape)
Painted with good quality auto paint and clear coat
Action screws torqued to 40 in/lbs as measured with a Borka ATK and Wheeler digital FAT wrench
BVSS action with a 1" straight taper bull barrel

I took the action out yesterday and did a visual inspection on the bedding. I can't see anything that would cause the action to sit skewed in the stock. The bedding is not cracked or visibly malformed, and no foreign objects or materials were found. The barrel was floated enough that a dollar bill would easily pass the entire length of the barrel channel. Now, when torqued to 40 in/lbs, the barrel makes contact with the stock and the bill won't pass.

Additionally, when the rear action screw is torqued to spec the bolt binds in it's fore/aft travel. I tested this with torque values ranging from 15-40 in/lbs in 5 in/lb increments. At 35 in/lbs, the bolt moved freely. At 40 it was bindung up. Even at 38 it would move ok, but by 40 it was sticking. This leads me to believe there is a high point somewhere that when the action screws are torqued causes the action to flex enough to cause the binding. The high point, I'm guessing is the contact point of the barrel and the stock.

This condition is new. I've only had the stock a short time, and it's only been out to the range I think 4 times. I've always torqued to 40 in/lbs and the binding was never an issue.

I put this barreled action into a factory Savage F-class stock and when torqued to 40 in/lbs the barrel sits straight in the barrel channel, and the bolt moves freely. This leads me to think the stock has an issue but I don't know what else I can do to diagnose and resolve the issue.

Any input on this situation would be greatly appreciated. I can post pics if that would help.
Click to expand...

It appears that your bedding job is not as solid as it should be. I"ll ask what James did, does the Stock have proper pillars installed?

I would have given the barrel more clearance in it's channel than you have indicated you have. At least 1/16 inch to the side as a minimum. It is not as cosmetically appealing as the old "dollar bill thickness" but much more conducive to accuracy.

As for the actual fiberglass structure warping, it is usually not a problem with fiberglass stocks. They do not absorb moisture and are stable.
 
jackie schmidt said:
It appears that your bedding job is not as solid as it should be. I"ll ask what James did, does the Stock have proper pillars installed?

I would have given the barrel more clearance in it's channel than you have indicated you have. At least 1/16 inch to the side as a minimum. It is not as cosmetically appealing as the old "dollar bill thickness" but much more conducive to accuracy.

As for the actual fiberglass structure warping, it is usually not a problem with fiberglass stocks. They do not absorb moisture and are stable.
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I omitted the make of the stock so as not to appear to "sling mud" at the stock maker. But maybe the make of the stock in germane to the conversation. If I am out of line naming the stock, I apologize. The stock is a Long Range Benchrest model from Stockade Stocks. It does have pillars. I'm trying to understand the sudden nature of the issue. If the bedding were unstable or shifting in some way, would that be visible?

I'm going to try to attach a pic to give an indication of the degree of offset. Pen tip included for scale. :)

As per the photo, would this much barrel shift due to bedding be apparent as a visible defect, crack, flaw, looseness etc in the bedding material?

I'm reluctant to re-bed this stock until I really understand what went wrong. Something that went from good to bad in a week *to me* seems like it should have some visible defects in the bedding. No? Cracks? Looseness? I just don't get how this happened.

IMG_6982.JPG
 
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Fiberglass is the material with the lowest modulus of any of the materials we generally use for building stuff. That is to say, fiberglass is a lot more "floppy" and "flexible" than most things like steel, wood, aluminum, and just about anything else you can think of when "structural material" comes to mind. Strength and stiffness are not the same thing. It is easy to make a component plenty strong using a small amount of ordinary fiberglass, but to achieve stiffness the engineering answer all to often involves simply using a lot more material. This isn't a bad approach since it can be done without spending much more money, but it explains why cheap boats are relatively heavy.

It should be noted that the term "fiberglass" can apply to a wide range of composite concoctions. At the low end is the chopper gun system where strands of glass fiber are chopped into short pieces, mixed with inexpensive polyester resin, and applied into a mold. A similar process can be done by hand, sometimes with the addition of some woven fiberglass cloth Once the mold costs are amortized, the process is quick, cheap, and effective. Countless boats have been made this way and plenty of gun stocks too. By the way, polyester resin is NOT waterproof. It also shrinks during cure and for some time after coming out of the mold. But it's cheap and easy.

On the other end of the performance scale are items like Formula One race car components made from very special carbon fiber woven cloth and high performance epoxy resins nearly always manufactured in a very expensive autoclave. It's possible to make ultra stiff and very light gun stocks using a variation of this system, but if a stock is made this way, the owner would be well aware of it because of the cost involved. Slightly less sophisticated methods might involve high performance fiberglass cloth and/or room temperature cure carbon fiber epoxy systems. There are lots of way to skin this particular cat.

Normally epoxy systems don't shrink and change shape nearly as much as polyester based systems. Both systems have problems at elevated temperatures, but this is not normally an issue with gun stocks.

As you might imagine, a manufacturer can make a fine stock using composite materials, but to be good it must be properly designed, made with care using appropriate materials, and all the rest, just like any other stock.

I'm not familiar with your particular stock, but it might be the case that you have a stock strong enough to club a grizzly bear to death, yet not stiff enough to resist changing shape when you torque down your action, especially if your stock doesn't have pillars.

But don't despair. Most likely you can solve common problems yourself without spending a lot of money. Check the pillar system first. Perhaps all you have to do is add pillars and increase the clearance under your barrel a little bit.
 
Did you have the barrel off? I saw some really crooked barrels. It would appear the same. I also had some Very crooked fiberglass stocks, but they must have came out of the mold early ...... Jim
 
The stock does have pillars so that's already done... Unless one has come loose which I will check today. And yes I did have the barrel off the action, but I didn't consider this to be an issue since I checked it in another stock and the barrel sits perfectly centered in that stocks barrel channel.
 
fiberglass does shrink and swell just slightly more so than wood ( depending on the resins used) This information from researching various types of window frame replacements. Foam or some sections of wood are used for core areas to keep weight in line. A nice sunny summer day unit in car or trunk-van what ever 300+ degrees- yep its going to move. There is a cure time in the mold as well as out of it also again dependent on resins used. most fiberglass stocks I have come into contact with are basically a shell.
 
sgt_jamez said:
The stock does have pillars so that's already done... Unless one has come loose which I will check today. And yes I did have the barrel off the action, but I didn't consider this to be an issue since I checked it in another stock and the barrel sits perfectly centered in that stocks barrel channel.
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If a pillar came loose and allowed the action to shift, the bedding would have had to crack or break. if you bedded it and shot it was it all right before ? did you replace the barrel? Saw glue in's that the barrel was so crooked they couldn't get them out. If you lose the screws does it go back to center?....... Jim
 
Since you had the barrel off, make sure your recoil lug is properly positioned. If it's crooked, that could easily cause your problem. The other stock might have had enough lug clearance that it wasn't an issue.
 
James Lederer said:
Since you had the barrel off, make sure your recoil lug is properly positioned. If it's crooked, that could easily cause your problem. The other stock might have had enough lug clearance that it wasn't an issue.
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Plus +1 as the most likely culprit.
 
I did try to contact the mfg. So far, no reply. That was indeed my first stop.

I put on my bedding spuds to see how things line up with just the those spuds in contact with the pillars. Here's what I get...

2FDC8CAA-C43D-4039-B142-C1FCB8975CE6.jpg

EAC7EC14-EC38-4377-BA53-A04FE88A5369.jpg

So the barrel is still misaligned with the channel when only the spuds are in contact with the stock.

Here's a look at the recoil lug

5A78C77F-96CA-4BC4-B5F0-42023FEF6FFD.jpg

B0B376B8-12DD-4F14-92FB-983AA6B68576.jpg

I will be digging into the recoil lug area of the stock just to make sure there's nothing interfering with the fit, but I can't see anything so far that would be an issue. We are in the tail end of a heat wave with a high of 109F today so I will load up on iced tea and then hit the garage.

Thanks everyone for chiming in!
 
If the recoil lug is bedded tight, with little side clearance, it only needs a little misalignment to interfere. It looks in the picture as if the dowel pin might have a little space but hard to tell. If you carve a little extra clearance on the sides it may cure it. if not, I got nothing.
Is there any bedding material forward of the lug?
 
There is none forward of the lug, but it is tight on the sides. I am going to clear the bedding on the sides and see what that does.

-Ok, I just ground out the bedding on the sides of the lug with no change. I'm at a loss. I'm not sure what else I could do. Even without the receiver contacting the bedding, the barrel sits offset. I'm about to give up on this stock. Grrrr....
 
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How about that pin that is line everything up relieve around it a little. that is the problem with a barrel nut set up. When you bedded it did you add a couple of layers of tape to the bottom of the recoil lug?.... Jim
 
Fiberglass does warp as it cures and it takes some time for it to fully cure. Also, even if the fiberglass was fully cured, perhaps the filler cured(or is still curing) at a different rate, and causing the warpage. Id try something...Put a wedge of some sort between the barrel and forearm on the tight side and leave it in the hot sun for a full day..and see if it moves at all. I think this will answer the question as to whether the fiberglass stocks can move or not. Either way, it doesn't cost anything to do and will answer the question of if it can move due to warpage.

I've talked with body men, and have seen them put a ratchet strap around a fiberglass fender and leave it in the sun all day to get it to move enough to line up bolts holes, etc. Those guys work with fiberglass a lot more than most of us and if this guy says it works, I believe him.

Obviously, this is worth trying to see if it makes a difference. If it makes a difference, it proves that fiberglass does move. If not, you've lost nothing. Still, I think I'd keep trying to contact the maker. He should be able to be of help either way, IMO. I don't think that the action moving could cause this, given your description of how it's bedded and what you've already tried.

FWIW.--Mike
 
Jim - yes I wrapped 2 layers of tape to the sides and front of the lug. The mud didn't go forward of the lug face but it did cover the back sides and bottom. Yesterday I ground out the bottom a side "shelves" so there was no chance of contact around the edges of the lug. No change in alignment.

Mwezell - It's supposed to be 100F today and I have I'll try the wedge idea. I have nothing left to lose and at this point I consider this stock a write off. No word from the mfg yet. Disappointing but not unexpected. It took almost a year to get this stock and it only saw range use 4 times.
 
If it did warp, Take the bedding out and pillars and re do it. Sounds like you got it green right out of the mold. I had on that was twisted over 3/8" I contacted the seller he told a line of BS. about it was made that way for right hander. So I ask him why didn't you tell me that when I'm left handed. Don't expect any satisfaction from the maker ,,,,,,,, Jim
 
sgt_jamez said:
I omitted the make of the stock so as not to appear to "sling mud" at the stock maker. But maybe the make of the stock in germane to the conversation. If I am out of line naming the stock, I apologize. The stock is a Long Range Benchrest model from Stockade Stocks. It does have pillars. I'm trying to understand the sudden nature of the issue. If the bedding were unstable or shifting in some way, would that be visible?

I'm going to try to attach a pic to give an indication of the degree of offset. Pen tip included for scale. :)

As per the photo, would this much barrel shift due to bedding be apparent as a visible defect, crack, flaw, looseness etc in the bedding material?

I'm reluctant to re-bed this stock until I really understand what went wrong. Something that went from good to bad in a week *to me* seems like it should have some visible defects in the bedding. No? Cracks? Looseness? I just don't get how this happened.

View attachment 19600
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I have a h&s stock on a savage LRPV. It is warped and looks just like your does.
 
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