


Taking to my local gun shop, and re-counting the story, they were the ones who commented that there was nothing left of the rifling. Telling them I had been told the gun was only ~1-year old and had only fired a few hundred rounds, they kindly checked the serial number with GMK. GMK confirmed it was sold to a dealer in North Cotswolds 9-years earlier. So, in that time, the rifle had undoubtedly had thousands and thousands and rounds through and whether you can see that could have any impact on the rifling or not, a simple barrel change and not only was the rifling then apparent, but the group size had gone down to just 3/4 inch. If it hadn't taken over 6-months to reach the conclusion, I would have had more than a few words to say to the unscrupulous dealer I purchased it from in South Wales.
bewsher, 17 HMR bullets are not copper gilded, they are true jacketed bullets, polymer tipped in the case of the 17grn V-max and JHP for the 20grainers.They might be remfire rounds but the the style of ignition is the only resembalnce to the usual lead bulleted 22lr. 10K+ of these is going to have some effect on the rifling especially when you say its micro-groove rifling which i must say i have never heard of before in a 17HMR barrelMy HMR was treated to the same cleaning regime as my bigger centrefire rifles, carbon first, copper residue second.Ian.
Did not misunderstand bewsher, your your description was wrong mate, yes jacketed bullets are made out of a copper alloy gilding metal, what they are not is copper gilded which means applying copper to another surface mechanically.I am aware of Marlins use of micro groove rifling but not aware of whether CZ, Sako, Ansuchtz or anyother maker of 17HMRs uses this process.Ian.You misunderstand the descriptionPretty much ALL jacketed bullets are housed in "Gilding metal" jackets (usually a harder than copper alloy)BULLET JACKETSAll Sierra Match jackets are made from special gilding metal copper alloy composed of 95% copper and 5% zinc. https://www.hornady.com/assets/files/catalog/Hornady-2013-Product-Catalog.pdfHard-hitting and deep-penetrating, the GMX® (Gilding Metal eXpanding) bullet combines monolithic construction with pioneeringballistic design to meet the need for a premium, non-traditional bullet. Fully California compatible and approved for use in otherareas requiring the use of non-traditional bullets, GMX® is ideal for any sized game, from antelope to moose.The mono-metal design of the GMX® bullet is crafted from gilding metal — the same material Hornady® uses for the jacket materialin our conventional bullets.as for micro groove style rifling, its been around since the 1950's, its a Marlin patented name but the idea is the same in pretty much all rimfire barrels, compared to most CF (and even some RF) rifling cut between .0785"-.177" wide and .002-004" deep they are much lighter and often bevelled rather than square cutMarlin Microgroove BarrelsIn 1953 Marlin applied for a patent on Microgroove rifling (US Patent #3,100,358 was granted on Aug. 13, 1953) In this patent, Microgroove rifling was described as having 5 grooves for every 1/10th of an inch bore diameter, and that the driving side of each land would be "tangentially disposed" (i.e. beveled, presumably to prevent the accumulation of fouling). Marlin introduced Microgroove rifling in their .22 rimfire barrels, with 16 grooves that were .014" wide, and nominally .001-0015" deepIn their 1954 catalog, they outlined numerous advantages that this new form of rifling had, including better accuracy, ease of cleaning, elimination of gas leakage, higher velocities and lower chamber pressures. They also mentioned "...a bore of greater than standard size..." in their discussion of how Microgroove rifling did not engrave (distort) a bullet jacket as deeply as conventional rifling.![]()
Did not misunderstand bewsher, your your description was wrong mate, yes jacketed bullets are made out of a copper alloy gilding metal, what they are not is copper gilded which means applying copper to another surface mechanically.
I am aware of Marlins use of micro groove rifling but not aware of whether CZ, Sako, Ansuchtz or anyother maker of 17HMRs uses this process.Ian.