• Fixing Weak Primary Extraction

    I purchased a left handed "tactical" bolt handle and have a few questions. I am installing it on a previously owned mdl 10 flp that it appears may have been sold due to primary extraction problems. The rifle is virtually unfired and will not reliably extract cases with the original or new bolt handle (bolt lifts fine but will often not pull straight back...cleaning rod, light tap, drops the bolt back). There are no pressure signs on fired brass. The original bolt handle had about .020" primary extraction (as measured using "Sharpshooter's" excellent description... from disassembled action face with bolt closed versus bolt lifted, pushed forward). The new bolt handle has even less, about .011".

    I know the normal "fix" is to shorten the bolt "tube" so the handle ends up forward relative the rear baffle/primary extraction ramp, but the bolt handle is already hitting the receiver cutout when closing.

    I understand the normal spec for primary extraction is minimum .050" to a max of .080".

    I have (for the time being) installed a .030" shim in front of the rear baffle/primary extraction ramp which gives me .041" extraction and seems to function properly (advantage of no permanent mods yet). With no shim the gap, baffle to receiver bridge, was .040" measured with feeler gauges. I also have a "F" class that has a rear baffle considerably thicker(but right handed versus the 10flp)... has anyone ever sold "+" sized rear baffles to fix this problem? Would you guys, in your opinion, shorten the bolt tube anyway and relieve the receiver cutout? I would love to send the action to SSS for "time and true", but the hassles of shipping across the border are substantial. Any help would be appreciated.


    Quote Originally Posted by BillPa View Post
    Before doing anything, be sure the extractor isn't worn or has excessive play and moving out(away from the bolt face) when engaging the cartridge rim. If it moves .010" you've lost .010" PE. I haven't run into that situation, but its something I check never less.

    But, an "Unofficial" cheat instead of shortening the bolt body, drill and tap two 8-32 blind holes on each side of the rear baffle where is contacts the rear bridge then install two set screws. Adjust them out checking until you have about .060-.070" PE. Check the gaps between the bridge and baffle on each side making sure they're equal. What its doing is moving the baffle back closer to the bolt handle instead of moving the bolt handle closer to the baffle (PE cam). Once you have them setup, measure how much they protrude, remove them and apply some 243 Loctite then reinstall them to the protrusion you measured earlier. Recheck the PE and side to side gap.

    You may want to check the bolt handle to recess clearance. Ideally it should be on center with the lugs against the abutments, but should have some clearance either way. You may need to shim the bolt handle back to gain some clearance or mill the recess. I'm hoping someone didn't try to true the locking lugs and take too much off. There is only about .010" meat between the bottom on the extractor spring bore and the lug face. If you end up installing the set screws in the baffle, the PE is easily adjusted-readjusted if you need to relocate the bolt handle.

    Bill


    DISCLAIMER:
    The information contained in this article and the attached video are for educational purposes only. Should you choose to use this information to alter or modify your firearm you do so of your own accord. In doing so you accept full responsibility for any adverse affects, damages, injuries and/or death that may occur as a result.


    Comments 1 Comment
    1. Ring's Avatar
      Ring -
      good stuff, but would be better with pics :)