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Thread: RFI: Pre-Fit Barrels

  1. #11
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    The barrel nut system works, but takes too long and you have to recheck headspace each time. With actions such as Bighorns TL3 and Origin, Defiance Ruckus, Impact 737, and a couple others- you can buy shouldered prefits. These actions have no “minimum/maximum” slop like a factory action. They are built to an exact specification. The barrel makers (like Proof Research) have the exact action dimensions provided by the action mfg. They then make barrels to that exact spec. This system is perfect. For example: both my hunting buddy and I both have Origin short actions. I had a 6.5 PRC Proof CF barrel that would shoot 0.3 MOA groups. I took the barrel off my action, torqued to spec on my friend’s action. Results: same 0.3 MOA groups with the same ammo. No need to check headspace. You can if it makes you feel better. I did myself with the first couple Proof barrels. I would not, and can not recommend a factory action or rifle anymore.

  2. #12
    I have two Savage rifles, a 243 and a 7mmRM. I have nice Stockade stocks for them.

    The 7mm has a skinny barrel I should have never bought.

    I was planning to shoot up all of the 243 components and then switch it to 6.5CM. But I think I will probably just get a barrel and it can live for now on the long action. A friend recently built a short action cartridge on a long action he had and said it has been helpful with some longer bullets. The Savage is easy to swap the bolt face also.

    Sent from my SM-G892A using Tapatalk

  3. #13
    Site Supporter OlongJohnson's Avatar
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    Quote Originally Posted by msstate56 View Post
    These actions have no “minimum/maximum” slop like a factory action. They are built to an exact specification. The barrel makers (like Proof Research) have the exact action dimensions provided by the action mfg. They then make barrels to that exact spec. This system is perfect.
    Pardon me while I pull on my pedantic douchebag hat. Precision in manufacturing and in language matters quite a bit to me.

    The actions you discuss do have “minimum/maximum” slop, it's just a much tighter range than typical and apparently even better factory actions. But there is a tolerance, however small. There is no such thing as exact or perfect, there's only the inability to measure more precisely.

    My interpretation of the story you told is that they hold sufficiently tight tolerances that you can assemble any set of parts within that ecosystem and the result will be close enough to the same that the performance will be the same. That's tight, but it's not zero, because there's no such thing as zero in the real world.
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  4. #14
    Does anybody know how mass produced stuff gets headspaced? I gotta think, but do not know, that chambers a cut to a tollerance and just checked when the action gets screwed on?

    Seems like shouldered barrel swapping should have always been possible.

    Sent from my SM-G892A using Tapatalk

  5. #15
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    Do the “prefit” ready actions have a allowable tolerance? Sure they do, but it’s small enough that it doesn’t matter. Why harp on a measurement that’s inconsequential? I told an anecdote for sure. But it’s not like it’s a one off event. You can take any Origin action that’s ever been sold and do the exact same thing. Manufacturing has gotten so much more precise. Some people are still under the old way of thinking when you had to have a gunsmith precision measure and fit parts to your specific action. That’s just no longer the case with the Origin, TL3, et. al. I have a standard and magnum bolt head for my Origin. The magnum bolt head was purchased separately from the action. I did not have to send in my action for Bighorn to fit a new bolt head. Bighorn makes everything to a standard, and their “off the shelf” parts are completely interchangeable. If you don’t trust or believe that it’s possible, that’s your opinion; however, the system has been proven for several years.

  6. #16
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    Quote Originally Posted by mmc45414 View Post
    Does anybody know how mass produced stuff gets headspaced? I gotta think, but do not know, that chambers a cut to a tollerance and just checked when the action gets screwed on?

    Seems like shouldered barrel swapping should have always been possible.

    Sent from my SM-G892A using Tapatalk
    It depends on the mfg. Some like Rem, Tikka, have the barrel torqued on then the chamber it cut to headspace. Savage uses a prechambered barrel and headspace is set by the barrel nut. Shouldered prechambered barrels are not possible with these factory actions because the tolerances are too variable. That’s why gunsmiths have made a living out of “blueprinting” or truing Remington 700 actions. Also most of the factory barrels are torqued on so tight that you have to grind a relief cut in front of the recoil lug just to get the barrel off, thus destroying the barrel. Otherwise you risk damage to the action by applying too much torque.

  7. #17
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    Quote Originally Posted by msstate56 View Post
    It depends on the mfg. Some like Rem, Tikka, have the barrel torqued on then the chamber it cut to headspace. Savage uses a prechambered barrel and headspace is set by the barrel nut. Shouldered prechambered barrels are not possible with these factory actions because the tolerances are too variable. That’s why gunsmiths have made a living out of “blueprinting” or truing Remington 700 actions. Also most of the factory barrels are torqued on so tight that you have to grind a relief cut in front of the recoil lug just to get the barrel off, thus destroying the barrel. Otherwise you risk damage to the action by applying too much torque.
    I haven't heard of any issues with the Tikka shouldered prefits from Proof. I was surprised when they came out, but Tikkas must be consistent enough to make shouldered prefits.

  8. #18
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    Quote Originally Posted by joshs View Post
    I haven't heard of any issues with the Tikka shouldered prefits from Proof. I was surprised when they came out, but Tikkas must be consistent enough to make shouldered prefits.
    Yes, to clarify- Proof offers prefits for Tikka, I'm sure they work or Proof wouldn't sell them.

  9. #19
    Quote Originally Posted by msstate56 View Post
    It depends on the mfg. Some like Rem, Tikka, have the barrel torqued on then the chamber it cut to headspace.
    That is what I would have expected. If typical headspace tolerance is ~.010 (is it?...) it shouldn't be too hard to manufacture a receiver that could be reliably re-barreled.
    One thing that occurs to me is that we gun enthusiasts might tend to think the typical manufacturing precision of a typical gun manufacturer might be more precise than it actually is.

  10. #20
    Site Supporter OlongJohnson's Avatar
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    0.010 is way big.

    SAAMI publishes their manuals with approved chamber dimensions for all the cartridges they register. You can download the PDFs and geek out as long as you want.

    https://saami.org/technical-informat...ami-standards/

    @msstate56 is making the point that some manufacturers are running tight enough tolerances that any combination of bolt/bolt head, receiver, and barrel will land in spec, perhaps even within a range narrower than what spec allows.

    Just as an example, the chamber headspace dimension for .308 is 1.630 min, 1.640 max. So the key dimensions on three parts have to all be held tight enough that any samples will all screw together and end up with a combined variation of 0.001 or less.

    Not shabby. Not cheap to accomplish. Unlikely to be done on rifles that sell for $400 retail.
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