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Primary Extraction Specifics?

I understand primary extraction and how to correct for it, but im curious if theres a specific minimum number that needs to be hit for successful primary extraction? A number I've heard thrown out not to go below is .060. The reason im asking is I hace a Remington 700 with like .085 primary extraction and .045 cock on close and the corners of the lugs have been chamfered by previous owner. Im wondering if i can machine off .015 off the back of the lugs to help the cock on close and still have enough primary extraction? Yes i know reducing cock on close will shorten my F.P. fall but i already had plan to recut the ramp.
 
Some customs only have .050" and that seems to be enough. After you re cut the cocking ramp you will have more work to do to make use of it to get the pin fall back and eliminate coc. Cutting the lugs wouldnt be what I would do. Chamfers on the lugs can increase cock on close though, but .045" sounds pretty normal.
 
Some customs only have .050" and that seems to be enough. After you re cut the cocking ramp you will have more work to do to make use of it to get the pin fall back and eliminate coc. Cutting the lugs wouldnt be what I would do. Chamfers on the lugs can increase cock on close though, but .045" sounds pretty normal.
Correct, id only be getting rid of .015 of cock and still have 30 left. I was just trying minimize how much id have to modify the cocking piece. I was under the assumption that in the best world we dont want any chamfer (maybe just breaking the edge a little) on the leading edge of the bolt lugs. Is that true or no?

Regardless what i would need to do to eliminate cock fully would be grind the cocking piece back then trim the rear of the F.P., rotate 90 degrees and drill a new hole to get back the pin fall then cut the cocking ramp deeper so that the Cocking piece has enough room to travel. Is that correct?
 
It depends on how much chamfer. Some actions put the closing cam on the lug in the form of a huge chamfer, so the chamfer in itself it not the worst thing. But if it is adding cock on close that we dont want it can be annoying. Still I dont think I would worry about it, by the time its that bad you would have to cut so much off the lugs to remove it you would really mess things up.
 
I understand primary extraction and how to correct for it, but im curious if theres a specific minimum number that needs to be hit for successful primary extraction? A number I've heard thrown out not to go below is .060. The reason im asking is I hace a Remington 700 with like .085 primary extraction and .045 cock on close and the corners of the lugs have been chamfered by previous owner. Im wondering if i can machine off .015 off the back of the lugs to help the cock on close and still have enough primary extraction? Yes i know reducing cock on close will shorten my F.P. fall but i already had plan to recut the ramp.
How much FP fall do you have now?
 
How much FP fall do you have now?
I had .253 FP fall. What i actually did today was weld a bead of material in the overly large detent in the back of the bolt and then machine the back of the bolt flat and clean up the ramp temporarily. After that the flat allowed the handle to rotate farther down before the CP was handed over to the sear and i had .031 cock on close. I took .005 off the back of the bolt lugs (they were somewhat galled). I ground about .020 off the CP and now have about .005 or less of cock on close and .222 FP fall. I've got about .025 clearance under the CP tip already so the ramp doesn't need dropped too much more. Here's where your guys extra experience may help me out, I can't decide if i should drop the ramp first then flip the FP 90 degrees and drill the hole second after i know how much i need to move the hole or should i just plan for about .250 fall and drill the hole .028 forward first and fit the ramp to it after?

Also if its not that far to move the ramp is it possible or easier to just hold the bolt fixed and use an end mill to just plunge deeper along the straight side of the ramp and then just use a cratex wheel to blend that deeper hole to the existing ramp?
 
Old thread, but any error in the cam helix will make the action open very hard. If you want it to open smooth the helix has to be machined, its near impossible to do it by hand and get it right.
 
I'd love to hear more on how you do this Alex, but I'm sure it is a "trade secret".

I've never bothered with trying to match the helices as that's way above my skill level, but I don't have any problems with hard lift. For RR actions, I discard the stock Remington bolt handle and solder on a PTG handle pretty much as-is and set it to 10-15 thou off the action. Looking at a well-used bolt (about 3250 rounds) that was prepared this way, I see that the contact is only at one point and I'm sure that can be improved, but with a reasonable .308 load and F-class shooting, I'm very happy with it.

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I had .253 FP fall. What i actually did today was weld a bead of material in the overly large detent in the back of the bolt and then machine the back of the bolt flat and clean up the ramp temporarily. After that the flat allowed the handle to rotate farther down before the CP was handed over to the sear and i had .031 cock on close. I took .005 off the back of the bolt lugs (they were somewhat galled). I ground about .020 off the CP and now have about .005 or less of cock on close and .222 FP fall. I've got about .025 clearance under the CP tip already so the ramp doesn't need dropped too much more. Here's where your guys extra experience may help me out, I can't decide if i should drop the ramp first then flip the FP 90 degrees and drill the hole second after i know how much i need to move the hole or should i just plan for about .250 fall and drill the hole .028 forward first and fit the ramp to it after?

Also if its not that far to move the ramp is it possible or easier to just hold the bolt fixed and use an end mill to just plunge deeper along the straight side of the ramp and then just use a cratex wheel to blend that deeper hole to the existing ramp?
That would be how I would do it, but I am a rookie with this stuff at best! Maybe Alex will throw us a few crumbs!! Or send us a pm if this is proprietary to his business. Either works for me, just would like to know so I can do this on my new build. As mine has a lot of cocking on close. Quite annoying on this particular action.

Paul
 

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