I'm sighting in a new Browning X-bolt chambered for 300 WM. Shooting 180 grain SPBT bullet at 3050 fps. I'm shooting 3 in a row (maybe a minute between shots) at 100 yds. My first shot tends to be almost an inch higher than the 2nd and 3rd hits which are less than 1/2" apart. I let the barrel cool and the next 3 shots were a repeat of the first 3. Have others found this typical to shoot a whole inch higher one the first shot at 100 yds?
- Thread starter bluetickjr
- Start date
It's not uncommon for the first shot on a cold barrel to be way off. What's uncommon is for that to happen again in the same session after letting the barrel cool down a bit. "Cold" means cold, as in unfired in the last hour or so. Waiting 5-10 minutes for a barrel to cool down between strings of fire should not, in my experience, result in another way off cold-bore shot.
Try different ammo and verify that the results are similar. Also shoot 5rd groups and see where shots 4 and 5 land.
I once had a Savage .308 that had a cold bore 1st shot that was 1 MOA different from warm barrel shots. I eventually ended up wearing the factory barrel throat out and screwed in a new Shilen match barrel. With the Shilen barrel, cold bore shots were dead on with warm barrel shots.
Since this positive experience of mine with a quality aftermarket barrel, I'm suspecting that the double stress relieving in aftermarket barrels might have something to do with helping or eliminating this phenomenon. Pulling a rifling button through a bore when making a barrel induces stresses which may alter a bullet's direction depending on different temperatures of the metal. The second stress relieving on aftermarket barrels is done after the rifling process.
Since this positive experience of mine with a quality aftermarket barrel, I'm suspecting that the double stress relieving in aftermarket barrels might have something to do with helping or eliminating this phenomenon. Pulling a rifling button through a bore when making a barrel induces stresses which may alter a bullet's direction depending on different temperatures of the metal. The second stress relieving on aftermarket barrels is done after the rifling process.
