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Precision rimfire state of the Union for 2025, help get me up to speed please…
- Thread starter jbell
- Start date
This Varmint Al website says that tuners work by launching slower bullets with a higher launch angle than faster ones. The website includes a chart illustrating the trajectories of slower and faster rounds, showing the slower and faster rounds arriving at the same elevation at 50 yards. Varmint Al is describing positive compensation where tuner settings are established for fixed distances.
Readers may wonder if the same tuner setting is supposed work at a variety of distances, is the Varmint Al tuner explanation missing something.
I don’t really buy positive compensation. Especially not with a heavy profile barrel. There are some slo mo videos out there you can watch and you won’t see any vibrations in the barrel. I’ve seen ammo with a high(er) ES shoot better than ammo with a low ES at 50. Obviously the farther you shoot the more the ES would come into play. Also, if tuners work by positive compensation then you can only tune for 1 distance. In which case why would they be marketed towards the PRS crowd….. more money
Top to bottom, Anschutz AT-X, factory barrel .900"
RimX AT-X, Bartlien #14
My brothers Anschutz AT-X custom barrel, 25" 1.15 cylinder.
All three weigh 20 lbs
Rimfire NRL/PRS is relatively new so a lot of what has been tested has been for a fixed distance. We shoot 50 to 300 and ELR guys out there at 700 yards. You can find a tune that will work good at 50 and at distance. Lot testing is similar as you are finding a lot that works for that particular rifle, at the end of the day it is simply timing. Set up a Garmin and record free recoil vs putting your shoulder into it. You have changed timing.
Indeed. If a setting is good for any .22LR distance is puts into doubt the PC explanation for how a tuner does what it does, unless PC is valid only up to a certain distance and something else explains how tuners work beyond that.
The suggestion that a Garmin (or any chronograph) can record changed timing is curious and puzzling. Variations in rifle set up can influence what a tuner does, which is why it's so critical to set up at the bench the same way when using the same tuner setting. Change set up and the rifle may respond accordingly with different results on target.
Perhaps this may be a reason militating against the use of a tuner in a variety of changing shooting positions to achieve repeatable and consistent results.
I think he means exit timing. Because changing from free recoil to a good shouldered position could change the muzzle velocity. But I’ve only heard that about centerfire. I’d be interested to see if it made a difference with a heavy PRS rimfire rifle. I’m guessing it doesn’t but who knows.
Chronographs don't measure exit timing.
No one can know whether or how much changing from free recoil to shouldered changes the muzzle velocity. The MV of a round is not known before it's fired, no matter how the rifle is held or not held.
