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Thread: Cutting forward caming area

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    Gunco Rookie Brokengun's Avatar
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    Default Cutting forward caming area

    Cutting forward caming area

    Does anyone know how the manufacturers machine the forwardcaming area in a bolt rifle?

    I followed a link the other day to a web site that sellsblanks t o make a Remington 700.

    http://www.clockworkarms.com

    But to finish one so that its worth using you will need tomill the forward caming area but I have never seen anyone come up with a slickway of doing it.

    Any thoughts or ideas?

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    There a couple of good threads about that on the practicalmachinist forum in the gunsmithing section. Search for "closing cam" or just "cam."

    Here's one to start with: Receiver locking lugs-construction

    There's some really good stuff on that forum once you learn to ignore the losers who only log on to crap on everyone else's parade.

    Basically, it's a manually operated shaving tool using a helical cam groove; looks dirt simple to make.

    If you're building a target or benchrest rifle, you can shorten the closing cams considerably to regain lug area, stabilize the bolt a bit more, and get more lug area. If you're going to hunt with it you'll probably want to replicate the factory cams, which are there to close the bolt on off-size ammo or a dirty chamber.
    Perge, scelus, mihi diem perficias.

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    Thanks for the link.

    Do you happen to know the angle needed to cut a forward cam?

    I did notice the book link from JPFO but I couldn't make it work but I found that I had another link.
    I suggest everyone makes copies and share with friends while this type of info is still available.

    http://www.scribd.com/doc/3615602/BA

    Selfmade Mauser bolt action receiver

    Index of /guns/boltaction

    A Guide To The Drilling Reaming And Broaching A Bolt Action Pdf free ebook download

    A Guide to Drilling, Reaming, and Broaching a Bolt-Action Receiver at Home

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    I don't know what angle a Remington uses... but on the Springfield and P-17, it's the same as the angle on the bolt. If you already have the bolt you can measure that.

    There are some good action truing threads on benchrest.com, where guys have recut the locking and camming surfaces.Most of them are working on Remington or Savage actions. I don't have any links saved, but they should show up on a search there.


    You might want to snag a copy of "United States Rifles and Machine Guns" by Colvin and Viall. It's in the public domain now; there are at least two different PDFs of it out there, one scanned by Google, one scanned by a college, and maybe a third. The resolutions of the scans vary a bit. You can also find both original copies and reprints on half.com or amazon.com.

    Despite the name, the book is 97% about the production of the 1903 Springfield rifle... all of it, right down to fixtures, speeds and feeds, and complete blueprints and material specifications; it was written for government subcontractor shops. The drawings aren't great, but there are lots of them. You *need* that book; snag a PDF from archive.org or Google Books.

    The raceways of the 1903 were produced by "shaving"; basically a big rifling head, as opposed to broaching or EDM. The cam angles were also produced by "shaving", essentially, the same method used in by the PM forum guy, except with fancier equipment. It doesn't remove metal very fast, but you're only removing a small amount of metal.


    I don't think most of the guys building from blanks are worrying about the cam angle; they seem to be benchrest types, and since they can guarantee clean, in-spec ammo, the chamfer on the bolt is sufficient for their purposes.
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    Oh, and if your mad internal threading skillz are questionable, I don't see any reason why you couldn't bore the front of the receiver and press the barrel in with a crosspin. It works for 8x57 and 7.62x54R Kalashnikovs and the vaunted H&K G3 in .308. Some of the extreme benchrest guys claim the threaded joint between the barrel and receiver shifts and acts like a hinge under firing pressure, and they're going to absurd amounts of torque on the barrel to compensate. I don't know how much actual range proof exists of their theory, but a pressed and pinned assembly is near-as-dammit one piece.

    BTW, the H&K's barrel pin is *much* smaller in diameter than an AK pin... AKs run .001-.002" of interference fit, btw. I don't know about H&Ks, but I expect they would be similar.
    Perge, scelus, mihi diem perficias.

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