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Thread: bolt engagement

  1. #1
    Boolit Master
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    bolt engagement

    I am curious as to how much bolt engagement with the happy bolt locking lugs is needed. most of the lever guns actually have?

    And how much is actually needed?

    At least in theory

    Like the old question of "is it a genuine military spec 1911 if it doesn't have BOTH lugs fully engaging with the slide?"

  2. #2
    Boolit Master Hick's Avatar
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    My lever guns don't have bolt lugs-- they have a solid block that slides up behind the bolt after it closes-- a much different situation. Don't know about Marlin and Rossi, I only have Winchesters and a Henry.
    Hick: Iron sights!

  3. #3
    Boolit Master
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    the 1886 has two separate lugs.

    And I was wondering in general, because the locking lug is not the only thing that keeps the bolt locked shut in the original henry design, the toggle link assists and when the gun blows is supposedly going to lock the whole bolt shut.

  4. #4
    Boolit Master Hick's Avatar
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    You got me-- I don't know. Hopefully someone who does will chime in
    Hick: Iron sights!

  5. #5
    Boolit Master pietro's Avatar
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    (doh)
    Last edited by pietro; 09-19-2017 at 02:39 PM. Reason: pilot error
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  6. #6
    Boolit Master pietro's Avatar
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    Levergun locking bolt fitment is important for a few reasons - optimum accuracy, stress equalization, headspace control, and functionality/operating smoothness.

    The interface(s) between the locking bolt(s) and the receiver abutments should in a perfect world engage each other fully (100%) and evenly - which is usually achieved via careful (and expensive, labor-wise) hand fitting.

    As (either) a locking bolt or abutment face wears during use, the cartridge headspace distance (from the bolt face to either the cartridge rim recess or to the shoulder area of the chamber) will change, sometimes causing shooting issues usually needing correction (gunsmithing).

    Rough and/or uneven interfaces are one of the areas than can contribute to less than optimum smoothness when cycling the action.

    Most leverguns have relatively thin receiver sidewalls and unequal locking lug pressure can induce undue stress into them.


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    Last edited by pietro; 09-16-2017 at 06:11 PM.
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  7. #7
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    ..............One my 2 Rossi M92's the twin lugs reach up to just above the sides of the action top. There is a couple thousandths 'Play' if you pull the bolt back against the twin lugs. However I think in chambering a round the lugs are pushed back this amount anyway. Not having any issues with my 2 x M92's, M1886, or a couple 1893 Marlins as regards headspace.

    Not wanting to discount any real issue you might be seeing in your own rifle, but most 'Rear lockers' seem to have a bit of play built in. Your mileage may vary, you're smart to pay attention to it.

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  8. #8
    Quote Originally Posted by Minuteshaver View Post
    the 1886 has two separate lugs.

    And I was wondering in general, because the locking lug is not the only thing that keeps the bolt locked shut in the original henry design, the toggle link assists and when the gun blows is supposedly going to lock the whole bolt shut.
    at
    The Winchester 1892 also has those two lugs in the side of the bolt. It is the 1894 that went over to the single lug behind the bolt, pivoted in a hinged floorplate, in order to permit longer caveartridges in a small action, and gave up a little smoothness to do it. The 1873 had only the toggle-joint (a valuable patent inherited from the otherwise pretty useless Volcanic rifle) and no locking lugs at all. I am amazed that it lasted so long on the market when the 1892 was available.

    For me the 1886 and 1892 are the perfect Winchesters. The genius of John M. Browning was in realising "Who says we have to pivot the lever in the receiver?" The largely unlamented Marlin 1881 had been doing that, like the modern 39a .22 and its ancestor, my other 1892, the Marlin rimfire. But they were nowhere near as strong as the 1886, and the 1881 was a very large receiver.

    I'm not quite sure what was meant by the original query, but the engaging areas are largerspect than much higher-pressure bolt-action rifles, and it appears to be enough. My 1886 extrudes primers by all of its .005in. headspace - and with modern brass the .40-82 case holds the chamber so that it isn't pushed back to reseat or mushroom them, and doesn't stretch brass. It wouldn't be ideal headspace in a high pressure in a higher pressure cartridge, but I can see no harm done, and I suspect that it was made that way. My loads were moderate smokeless ones, but perfectly adequate for hunting.

    Similarly I can't see any way accuracy would, in that situation, be harmed by more contact on one lug than the other, or more at the top than the bottom. If pressure was high, I think stretching of that long case-hardened mild steel receiver would take place till contact was even, and then stop. If pressure wasn't that high, nobody would ever notice.

    Winchester produced high-velocity smokeless loads in the early 20th century, then discontinued them. Possibly they just wanted to sell more 1894s. One opportunity I think they missed would have been to introduce something like the .44 Magnum for the 1892. Maybe they were afraid people would modify .44 Special revolvers and blame the result on them.

  9. #9
    Boolit Master
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    I play with a mosin nagant rifle for fun, the three locking bolts are a good thing for crappy ammo made in Russia. the regular bolt head has two, and the big section of metal that is part of the bolt handle is the emergency lug, that has nearly 3 times the cross section of the regular bolt lugs.

    I was just wondering if there was a similar safety margin in the lever action, I know the toggle action has two "safety options", if the chamber pressure is to much it just jams the whole gun up, and if the chamber pressure is really to high, it just explodes.

  10. #10
    Quote Originally Posted by Minuteshaver View Post
    I play with a mosin nagant rifle for fun, the three locking bolts are a good thing for crappy ammo made in Russia. the regular bolt head has two, and the big section of metal that is part of the bolt handle is the emergency lug, that has nearly 3 times the cross section of the regular bolt lugs.

    I was just wondering if there was a similar safety margin in the lever action, I know the toggle action has two "safety options", if the chamber pressure is to much it just jams the whole gun up, and if the chamber pressure is really to high, it just explodes.
    There is a dangerously misleading safety option, and not a little misleading, but very. PO Ackley experimented with a Winchester 1894 chambered for one of his Improved cartridges, with the locking lug removed. Everything held together. He unscrewed the barrel by first one and two turns o f its thread. The case held, the primers were extruded as far as that permitted, and the case stayed the put, without moving back to reseat or mushroom them. Everything was held in place by the floorplate and lever, inertia, the sealtrength of the brass and the momentary adhesion of case to chamber.

    So why do we bother with locking systems, when they are such a nuisance? More traditional cases adhere less than the Improved breeds. Some brass is thinner, over-annealed or overused. Chambers can be oily or wet. Some loads give a longer duration of high pressure than others... There are probably other factors none of us have heard of. When someone claims to be getting away with something, he may be getting away with it for reasons we can't be sure of repeating.

  11. #11
    Boolit Master
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    well, what company came out with a semi auto 22 magnum handgun the other year that used the expansion of the case as part of the locking system of barrel/slide?

    the MAS has a single lug in the back, the lee navy did as well, vetterli I believe has a single lug as well. SO since those good rifles of the bolt action family do fine with a single locking lug in the same place that the average lever gun has a single sliding bar of steel... I got curious

  12. #12
    Boolit Master pietro's Avatar
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    Quote Originally Posted by Minuteshaver View Post
    well, what company came out with a semi auto 22 magnum handgun the other year that used the expansion of the case as part of the locking system of barrel/slide?

    the MAS has a single lug in the back, the lee navy did as well, vetterli I believe has a single lug as well. SO since those good rifles of the bolt action family do fine with a single locking lug in the same place that the average lever gun has a single sliding bar of steel... I got curious

    The .22 mag handgun you're asking about is most likely the Grendel P-30, but AMT used the same technology over 35 years ago in their Automag II.

    Sure, the single locking lug boltguns do fine - but ONLY with their original chambering's.

    They are not suitable for more modern & high-intensity cartridges.


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  13. #13
    Boolit Master
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    ive seen the French MAS cartridge considered a European .308 Winchester,,,

    How would those single bolt lug friends do with something in the 357 or 44 magnum world?

  14. #14
    Boolit Master
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    they'd be fine.
    the 357/44 mag pressures are in the 30-30 range.
    bolt thrust would be similar for the 44/30-30 too.
    it's all an educated guess,,,, till the trigger is pulled.

    this opinion brought to you by mister low-tech solution..

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BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
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