I have a Sig970SHR in .270win and a Cooper in .270win. They both will give me groups like this. As the barrel heats up it gets more pronounced. Its a hunting rifle and it is what I expect. If I let it cool between shots, bolt open, 10 minutes they all touch. I did it once with a 10 shot group, it wasted a lot of time nearly 2 hours but proved a point. When allowed to cool the rifles both printed nearly the same hole over and over again. When I see weird stuff going on I will usually start by single feeding each round rather then shoot from the magazine. I've found certain lots of brass exhibit decreasing neck tension after the 3rd or 4th reloading allowing the bullets to jump forward during recoil. This changes internal case volume, which effects velocity and changes bullet jump distance to the lands, all of which will change POI.
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Quick question, root cause of 2 + 1 groups?
- Thread starter Darryle
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Weatherby Fan
Well-Known Member
That's dam good grouping with factory ammo, if it groups like that consistently it's the heating up of the barrel, one solution is pull the stock and see if there are any witness marks and remove any spots that are touching no matter how small.
In a hunting rifle nothing a 5 or 10 shot group will tell you a 3 shot group won't, shoot your 3 shot group at 300 and 500 yards and see what the rifle/barrel says as it heats up.
In a hunting rifle nothing a 5 or 10 shot group will tell you a 3 shot group won't, shoot your 3 shot group at 300 and 500 yards and see what the rifle/barrel says as it heats up.
Rflshootr
Well-Known Member
It's the ammo.....which is doing pretty good for factory ammo. If all the groups are like that, I wouldn't expect any better.
All it takes is for a crimp or a bullet seated slightly different, or a powder charge to be a little off. It doesn't take much. Factory ammo is made on production machinery. They have tolerances like everything else. They aren't all 100% perfect.
All it takes is for a crimp or a bullet seated slightly different, or a powder charge to be a little off. It doesn't take much. Factory ammo is made on production machinery. They have tolerances like everything else. They aren't all 100% perfect.
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25WSM
Well-Known Member
#5. It's always the third round. Its not the ammo.
Shep
Shep
Rflshootr
Well-Known Member
Then shoot the 4th and 5th shot to see what happens.
lyle2231
Well-Known Member
Weigh the loaded rounds and cull the light/heavy from the flock. Use those for warm up then the one in the "bracket" for the group firing. HTH
Stiletto150
Active Member
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I have an idea. Buy an infrared thermometer for $25 on Amazon or somewhere. I found tons of uses for cooking with it. Measure the same spot at the tenon of the barrel and the tip of the barrel. Before you shoot and then after your shot. That's if your barrel has metal on both sides to take a measure since it's carbon wrapped.
#1 Shot- Then let it cool. (Whatever time you like~5-10min.) Take #2. Repeat the temperature procedure. Take #3 and repeat the procedure. This should prove any barrel heat-up issue. My initial hypothesis is this: if you take 5min between shots 1 and 2. I bet the 3rd shot can't be taken until 7-15 min to cool back to the optimum first and second temperature. You also may want to check that the barrel is still free-floated at shots #3 #4 #5.
I don't think it's an ammo issue since it's repeatable with factory ammo and the odds of the 3rd cartridge always being off would be statistically improbable.
#1 Shot- Then let it cool. (Whatever time you like~5-10min.) Take #2. Repeat the temperature procedure. Take #3 and repeat the procedure. This should prove any barrel heat-up issue. My initial hypothesis is this: if you take 5min between shots 1 and 2. I bet the 3rd shot can't be taken until 7-15 min to cool back to the optimum first and second temperature. You also may want to check that the barrel is still free-floated at shots #3 #4 #5.
I don't think it's an ammo issue since it's repeatable with factory ammo and the odds of the 3rd cartridge always being off would be statistically improbable.
Spot on.
NMMerriam7401
Member
Barrel heat would be my guess!
Buckys
Well-Known Member
Darryle, I wonder what the 5 shot group looks like, too.
Without touching the rifling, might be interesting to touch either end of the barrel with a meat thermal probe prior to each shot and see if there is any correlation to the "flier".
Shooting over a labradar would also help you understand if the variability in ammo is correlated.
But given that it is always the third shot, I'd guess thermal.
Without touching the rifling, might be interesting to touch either end of the barrel with a meat thermal probe prior to each shot and see if there is any correlation to the "flier".
Shooting over a labradar would also help you understand if the variability in ammo is correlated.
But given that it is always the third shot, I'd guess thermal.
try a group at 400 yds and could be you need to try changing seating depth by a few thousands
Back in the day when I was young, 40 to 50 years ago, a rifle didn't have to group less than 1/2 inch to kill a deer; a 1 1/2" group was really good and acceptable. Now folks seem to believe that their rifle should group under a 1/2 inch or it's not worthy
It's always better when a rifle shoots small groups, but head shots at any range are always suspect, though I am sure many will disagree with that. Anyway, your rifle shoots dang well. I would enjoy it and not be concerned.
It's always better when a rifle shoots small groups, but head shots at any range are always suspect, though I am sure many will disagree with that. Anyway, your rifle shoots dang well. I would enjoy it and not be concerned.
Almost all three shot groups have 2 in and 1 out. Even if all three shots overlap, if you look closely there will be 2 in and 1 out. It's just odds. A perfect equilateral triangle in a shot group is rare. If you go to 2 shot groups the issue will dissapear.
In my experience, flyers are caused by 3 things typically. Seating depth not quite right, barrel contact, or stress in the action/bedding.
