Author Topic: Lube groove versus no grove  (Read 220 times)

Offline J Mercurio

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Offline PappaWheelie

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Re: Lube groove versus no grove
« Reply #1 on: November 13, 2018, 05:43:11 PM »
Very interesting, J Mercurio: thanks!
The lube grooved bullets showed consistency/advantage in both accuracy and velocity. The velocity might be from improved "labyrinth groove" sealing,
https://encyclopedia2.thefreedictionary.com/labyrinth+seal
http://www.skf.com/group/products/bearings-units-housings/bearing-housings/split-plummer-block-housings-snl-30-31-32-series/sealing-solutions/index.html
http://obbco.com/labyrinth-seals.html

to better capture the firing pressure, while the accuracy might be related to a Sheffield Groove effect, for which amazingly enough I could find NO online information!
Showing my age(?), even I know about the Sheffield Groove typically (in wartime, perhaps?) employed as an assembly aid for "SFNS" (Slip Fit No Shake) diameters to leapfrog past the "self-locking angle" that causes such fug snits (especially absent EP lube*) to hang up before enough engagement length ensures true piloting. The Sheffield Groove is located just inboard of the beginning of the rod's OD (outside diameter), and effectively acts like a swivel joint (the first land being too short to lock up) that helps align the rod when the other side of the groove begins to engage, safely beyond the self-locking engagement distance subject to sticking. It's a bit of a stretch, but conceivably the lube groove's Sheffield Groove emulation might more readily stabilize the bullet in yaw mode as it begins it journey down the rifling, with result of slightly more consistent "piloting" out the exit end of the barrel.

Please, somebody, assure me that they too know of (or have heard of) Sheffield Groove "technology."

*http://www.czforum.com/forum/index.php?topic=5566.msg23292#msg23292
« Last Edit: November 13, 2018, 06:05:00 PM by PappaWheelie »
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