04-30-2021, 08:12 PM
I have several CZ 527's (none in 6.5 Grendel). All of the rifles benefit from having the action bedded. As far as the magazines you can tweak them a bit, and it doesn't hurt to run a file and dowel wrapped in sandpaper along bottom edge of feed lips to break the sharp edges. Since there seems to be a shortage of additional Grendel magazines available for purchase, I'd wait until you have a spare or two before making any major modifications to the mag.
CZ's varmint barrel (heavy factory barrel) is comparable to a heavy sporter barrel, which is considerably lighter than a Rem Varmint/Sendero profile. It isn't made to handle long, fast shot strings that cause the barrel to heats up. Without knowing more, this may be the cause of your increase in group size after 20 rounds. The last CZ527 that I sold was a beautiful Royal (223), which had a sporter barrel. After 3-4 shots the barrel became hot enough that the group would start opening up. This was the case of a misalignment of my desired use and the rifle that I selected. This is seldom an issue with their rimfire rifles, which don't consume enough powder for the barrel to heat up.
CZ's varmint barrel (heavy factory barrel) is comparable to a heavy sporter barrel, which is considerably lighter than a Rem Varmint/Sendero profile. It isn't made to handle long, fast shot strings that cause the barrel to heats up. Without knowing more, this may be the cause of your increase in group size after 20 rounds. The last CZ527 that I sold was a beautiful Royal (223), which had a sporter barrel. After 3-4 shots the barrel became hot enough that the group would start opening up. This was the case of a misalignment of my desired use and the rifle that I selected. This is seldom an issue with their rimfire rifles, which don't consume enough powder for the barrel to heat up.