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Blue printing question? Lapping

 
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  #1  
Old 07-17-2014, 12:47 AM
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Join Date: Jun 2008
Location: christchurch, nz
Posts: 380
Blue printing question? Lapping

So I just got done blue printing my first action.(700) what a lot of tool making time vrs cutting time!!
When I color he back of the bot lugs and test them in he action I get what I think is perfect even wear. That's just holding he action upright and letting the weight of the bolt hold pressure down on the lugs. Once I put the firing pin assembly in though I just get one lug contacting. Concern? Do people test for contact with the pin in?should I sleeve the bolt? Should I lap the rings in?
Thanks
Ps. Forgot to mention that's with the trigger in.
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  #2  
Old 07-17-2014, 07:07 PM
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Join Date: May 2014
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Re: Blue printing question? Lapping

I made a mock barrel about 6 inches long out of steel threaded for a 700 action and recessed for the bolt nose then basically chambered it for a 7/16 diameter spring leaving about 1/4 inch of the spring sticking out of the "breach" then thread your action on with the recoil lug insert bolt and you should have plenty of tension holding the bolt tight in the receiver. Simply holding it upside down ain't gonna do it for ya
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  #3  
Old 07-17-2014, 07:12 PM
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Re: Blue printing question? Lapping

And not sure how your checking for contact but I use a dirty flame and hold the bolt a couple inches above it til it gets a good layer of soot on the back of the lugs then check it with the receiver
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  #4  
Old 07-17-2014, 08:32 PM
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Re: Blue printing question? Lapping

Quote:
Originally Posted by DakotaFire101 View Post
I made a mock barrel about 6 inches long out of steel threaded for a 700 action and recessed for the bolt nose then basically chambered it for a 7/16 diameter spring leaving about 1/4 inch of the spring sticking out of the "breach" then thread your action on with the recoil lug insert bolt and you should have plenty of tension holding the bolt tight in the receiver. Simply holding it upside down ain't gonna do it for ya

hey Dakota
think you miss understood my question. or i wasnt too clear. i know how to lap. just i have 100% lug contact without the firing pin mechanism in the bolt but once i put the mech in the trigger raises up the back of the bolt and i loose contact with one lug.
so my question was should i lap it in for that. just not what it seems like other people do.
cheers
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  #5  
Old 07-17-2014, 08:35 PM
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Join Date: Apr 2003
Location: North Bend, Oregon
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Re: Blue printing question? Lapping

foreign,
Your observations is spot on for a perfectly trued rifle. When the bolt face and lugs are all trued to the bolt raceway, only the bottom lug will touch with the firing pin and trigger are installed. If you lap it to bear evenly on the lugs when cocked you will be at least .001" out of square. Yes people check this all the time and will ask about it. Leave it alone and finish the rifle. I have to explain this to almost every custom rifle customer that is receiving their first custom.
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Last edited by Hired Gun; 07-17-2014 at 09:03 PM. Reason: spelling
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  #6  
Old 07-17-2014, 08:43 PM
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Re: Blue printing question? Lapping

thanks Hired Gun
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  #7  
Old 07-18-2014, 05:35 AM
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Join Date: Aug 2010
Location: Western PA
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Re: Blue printing question? Lapping

Bolt slop is what causes the top lug to pull away. The trigger pushes up on the bolt which has slop thus causing the bottom lug to act as a hing or pivot point. sleeve the bolt and lap only the bottom lug. I had one rifle go from a .4 to a .2 gun just by getting both lugs to touch on a trued receiver. That action had around .018 of slop on the bolt. Or get a PTG bolt and spec the size bolt body to get rid of the slop.
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