Gunsmithing bedding problems in heat? (SWMP Article)

CD0311

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Just read an articel on the Ashbury .338. It said that they went with an aluminum stock because

"fiberglass stock displayed problems with accuracy after rapid fire strings in high heat conditions. The titanium devcon bedding would start to melt"

1st time I have herd of this happening. Anyone else??
 

wnroscoe

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Re: bedding problems in heat? (SWMP Article)

Extreme heat will soften Bedding compounds. I've removed pillars by heat transfer among other bedded items. I can see where heat would play a part under certain circumstances. You have to choose your tools based on the AO and their expected performance.
 

ejg

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Re: bedding problems in heat? (SWMP Article)

Yes that can be true. If one has heat issues one must change the epoxy resin, up to the kind of resin that is used for making motorcycle exaust systems. Sometimes three component resins.
Just look at the data supplied with the resins. We temper our stocks in special furnaces with a temp profile over time so that they have a better stiffness at elevated temperatures.
Aeropspace resins supply the data. Devcon ??? maybe not

edi
 

wnroscoe

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Re: bedding problems in heat? (SWMP Article)

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 7mmRM</div><div class="ubbcode-body">Hot enough to melt Devcon Titanium??? </div></div>

Never tried the Titanium but, I have loosened 10110 with heat transfer. I heated a barrel cut off once with a hand held map gas torch, hot enough you couldn’t touch it. I stood it up on an escutcheon that was bedded into a McMillan Tooley MBR Stocks for 30 to 45 seconds. The Devcon 10110 loosened up enough that I was able to pull it out of the stock. Red Loctite and Rockset reacts the same way. Ever have a scope base screw that's hell bent to not come out. Place a hot pencil soldering iron tip on the screw head and watch it come out.

Getting a rifle hot enough to melt the bedding though, I dont know. Seems you'd have other problems besides the bedding being all jacked up.
 

7mmRM

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Re: bedding problems in heat? (SWMP Article)

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: wnroscoe</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 7mmRM</div><div class="ubbcode-body">Hot enough to melt Devcon Titanium??? </div></div>

Never tried the Titanium but, I have loosened 10110 with heat transfer. I heated a barrel cut off once with a hand held map gas torch, hot enough you couldn’t touch it. I stood it up on an escutcheon that was bedded into a McMillan Tooley MBR Stocks for 30 to 45 seconds. The Devcon 10110 loosened up enough that I was able to pull it out of the stock. Red Loctite and Rockset reacts the same way. Ever have a scope base screw that's hell bent to not come out. Place a hot pencil soldering iron tip on the screw head and watch it come out.</div></div>

I completely agree with all of that.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: wnroscoe</div><div class="ubbcode-body">
Getting a rifle hot enough to melt the bedding though, I dont know. Seems you'd have other problems besides the bedding being all jacked up.
</div></div>

My thoughts exactly.
 

former naval person

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Re: bedding problems in heat? (SWMP Article)

Probably why there isn't any wood or plastic on the front end of a machine gun. When you shoot it fast and long enough that the barrel glows and the asbestos gloves hurt when you change the barrel...think tiles on the space shuttle. I think it would be hard to shoot a bolt gun fast and hard enough for that to happen, but the epoxies are susceptible to heat softening as aforementioned. If it gets to that point, you better be shooting from a bipod...the forend bags are smoking. JMHO
 

Terry Cross

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Re: bedding problems in heat? (SWMP Article)

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Just read an articel on the Ashbury .338. It said that they went with an aluminum stock because

"fiberglass stock displayed problems with accuracy after rapid fire strings in high heat conditions. The titanium devcon bedding would start to melt"
</div></div>

That article is a bit misleading and doesn't tell the whole story.

The incident they are referring to is when the USMC was having some .338 trials at GunSite during August. Ashbury was running wide open to get a rifle on line for the shoot and their new stock was not quite ready. So they put the gun in a McMillan A5 and used a new bedding compound that was suppossed to be the newest, bestest.

So Ashbury was going to an aluminum stock all along, but at that time it just wasn't ready.

The fiberglass stock never had any issues. The new bedding compound did. It had a meltdown in the heat. I cannot confirm whether it was Titanium Devcon but I do know that the material was new to the users and done in a hurry.

The problem referrenced in the article was due to un-tested methods and materials used in their test gun. In fact another, similar rifle was used at the last minute for their actual shooting demo. That rifle had the same type A5 stock but bedded with proven bedding compounds. It never exhibited any issues and completed their demo wonderfully. This string of events could have happened to anybody under the circumstances. Ashbury had a Plan B and it worked out for them.

Even if the fiberglass stock and bedding had worked perfectly in the heat, they were already on track to move to the current aluminum chassis that they had heavily invested in. If anyone has info to the contrary, please share.

This is not a knock on Ashbury or their product. Both are top shelf. Rather it should be a reminder to not take everything printed in a gun magazine as the gospel.
 

Nocalphoenix

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Re: bedding problems in heat? (SWMP Article)

I seems like you would have structural issues with the fiberglass before the bedding would go. I know Mcmillan will not warranty their stocks over 160 (I asked about curing Cerakote at 200degrees).

This is from the Devcon 10110 specs
"Heating above 300 deg F in the presence of air may cause slow oxidative decomposition and above 500 deg F may
cause polymerization."

My laymans take on this is dont get it over 300degrees but it seems that would be darn tough with a bolt gun.
 

CD0311

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Re: bedding problems in heat? (SWMP Article)

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body"> it should be a reminder to not take everything printed in a gun magazine as the gospel.
</div></div>
+1


Thenks for the info Terry
 

fewenuff

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Re: bedding problems in heat? (SWMP Article)

Most epoxies, cept the bazillion dollars a gram nasa stuff, have problems going plastic or flowing at high temperature. Devcon is some of the best to resist it. Devcon titanium is rated as temp resistant but that only goes so far.

2 nonsense?
 

ejg

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Re: bedding problems in heat? (SWMP Article)

Problem is not really going plastic but the stiffness of epoxy just drops at higher temperatures. Once the stiffness changes accuracy might drop. Stiffnes of epoxy at higher temp doesn't only come from the brand or composition but also from the heat treatment after curing. Most high quality epoxies must undergo a specific heat profile to get used to elevated temperatures this is documented in their data sheet. In most cases aerospace quality epoxies will only qualify for aerospace use if the heat curing took place.

edi
 

fewenuff

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Re: bedding problems in heat? (SWMP Article)

Epoxy losing stiffness and dimensional stability at elevated temperatures are good things to be aware of. Cooking/curing can help.

Anyone take that extra step? Vacuum bag it? hehehe C-;

I think one would have to be careful with the stock, composite or otherwise. ???