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release agent and duracoat???

 
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  #1  
Old 03-30-2010, 05:28 PM
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release agent and duracoat???

I'm putting together a varmit rifle and plan on using duracoat on pretty much everything. Has anyone had experience bedding an action that has been duracoated? Im using the blue release agent that comes with acraglass because it has always worked pretty well. My thinking is that everything should be fine as long as the agent is applied well enough. Any advice or experiences would be appriciated.
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Old 03-31-2010, 07:26 AM
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Re: release agent and duracoat???

Make sure your release agent doesn't stain the duracoat, or, worst case, swell the duracoat and makes it debond.
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Old 03-31-2010, 10:42 AM
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Re: release agent and duracoat???

I use the acra release from Brownells. I've used it on several Duracoated barreled actions and have yet to have any problems.
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Old 03-31-2010, 04:42 PM
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Re: release agent and duracoat???

I've had no problem with the release agent when using the brownells kit on duracoat. HOWEVER, I did have a problem with the actual bedding and duracoat. When I removed an action from the bedding I had a slight spot run forward of the release agent and the bedding turned the portion of duracoat it touched into goo and stripped it off. Luckily it's on the underside of the barrel, so I don't mind, but it is something that should be noted.
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Old 03-31-2010, 07:11 PM
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Re: release agent and duracoat???

If it were me. . .

I just went through this with a client from out east. If you have not had the metal work coated yet WAIT!!

It's certainly possible to bed a gun that's been coated however your really creating a pile of extra work for yourself.

If you like to have a nice finish afterward where the inlets match the features on the action and ensure that all the surfaces are flush and clean, then your going to have to use a file/sanding block at some point to do the finish work. It is a certainty that you'll slip and nick the finish. It's a certainty that there will be some little flake of bedding that is stubborn and doesn't want to let go from the coating. You might scrub a little too hard when cleaning up the action after bedding to get the clay and funk off of it.

I recently bedded a Stiller action for a guy and his receiver was coated when I got it. If I'd of been smart I'd of boxed it all back up and sent it back to him. I decided to roll the dice and it bit me. I'm pretty darn careful with stuff, yet I did end up marking up his receiver. It cost me because I couldn't in good conscience send it back to him in a condition worse than when he gave it to me. I ate the cost of having to coat it again.

The important lesson here is DO THE PRETTY STUFF LAST.

Good luck.

Chad

Here's some pics of what I encountered:

Bedding job, no issues here:





Trying to clean stuff off afterward, notice the rubs, dings, and scratches: FWIW I used a WOOD popsicle stick and 0000 steel wool to clean this off.




Final assembly after all clean up work and after having the action coated again:

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Last edited by NesikaChad; 03-31-2010 at 07:17 PM.
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  #6  
Old 04-01-2010, 05:31 PM
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Re: release agent and duracoat???

if you apply Cerakote or other coating afterwards, on the underside of the action, lug etc, wouldn't that interfere with the fit of the bedding?
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Old 04-01-2010, 06:16 PM
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Re: release agent and duracoat???

GREAT QUESTION!

Short answer: NO!



Now for a long winded NesikaChad dissertation:

For almost as long as folks have been bedding rifles there's existed a procedure for inspecting it that involves a mag base indicator holder. You stick it to the barrel, touch the forend of the stock with the indicator and loosen the guard screws individually to see how much deflection you have from fully torqued to static with no tension.

The magic number to stay inside of is .001" and if your diligent and thorough you can cut that number in half. The film thickness of a coating is applied pretty dern uniform. I've checked everyone before and after bedding/coating/final assembly and I've yet to see a difference on the indicator or on paper.

This is over literally hundreds of guns and a decade of hands on experience.

Take it one step further and we'll really get down in the mud. Any of the better epoxies have a shrinkage percentage that hovers between one and two percent. I write all my own inlets with CAD software based off the individual action that I happen to be working with at the time. I use CNC equipment to machine them as surface models. My bedding film is .05" thick from one end of the inlet to the other. The exception is behind the recoil lug where I fatten it up a bit more to better tolerate the hammering it takes.

So, lets do some simple math. one percent of .05" is .0005". I'm sure there's a bit more to this, but lets just keep it simple for the time being. IF that is indeed the case then the action has a total clearance of .001" from a diameter perspective. I come to this conclusion because the epoxy is going to shrink and pull away from the receiver as it cures, there should be a theoretical .001" difference between the outside diameter of the action and the inside diameter of the bedding inlet. Meaning the "gap" got bigger and the action would in theory have "wiggle room" now. In practice anyone will tell you this is BS because of how snug an action can fit in a stock once its bedded.

But lets move forward anyway just for fun.

Lets say your coating is .001 to .0015 in film thickness which is a pretty accurate and fair dimension for the bulk of coatings out there. Using this figure Your only talking a difference of .0005" to .00075" per side.

To put this in a little different perspective the fit between the pistons and wrist pins on a 700+hp 13,000rpm NHRA Competition Eliminator (C altered) engine aren't held to a tolerance this close. ( I know because I used to work for a very successful team's engine builder in S. Cal in the early 90's as a machinist)

It's far enough "in the mud" that you can find it mathematically, but I can promise you you'll never see it in a million years on paper. There's too many off the shelf guns with no bedding to speak of that shoot just fine.

Hope this helped.

C
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Last edited by NesikaChad; 04-01-2010 at 06:29 PM.
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