Horizontal GROUPING ??? not Stringing ?

[HARV6]

So I just got Ruger All-Weather Hawkeye in 25-06 and began trying different factory ammo. All shot on the same plane vertically, but this is how the groups went:
...................................Group............ Position
100gr Rem Core-Lokt....... 1.25"............. .5" Left of Center
120gr Win PXP.............. .85" .............. .5" Right of Center
115 Fed. Partition ......... .53" ............... 1" Right of Center
100 Barnes TTSX .......... .42" .............. 2.5" Right of Center

Groups were 4 shots and I left the rifle cool to ambient temp. between groups. I've read about rifles that will horizontally string out individual shots of a group. And I've personally seen how my other rifles will space good groups out vertically when bullet weights change or when powder weights change with the same bullet. But I've never seen or heard of good groups being spaced out horizontally like that. Is it common? What causes it?

 

[barnbwt]

I always thought trigger control issues push the groups left/right. I suppose if your barrel is contacting the stock on its side rather than toward the bottom, barrel heating or differing harmonics could cause groups to wander in that direction.

If you've accidentally discovered that secret to making bullets curve in flight, be sure to let us all know

TCB

 

[Halal Pork]

Can you have someone else fire your rifle? I'm curious if another shooter, going from one load to the next, would duplicate the shifts you're seeing. Off the top of my head, I think of inconsistent sight picture or inconsistent cheek weld. But I could be completely wrong; so I go back to my suggestion to see if another shooter duplicates your results shift-wise.

 

[Andrew Leigh]

So I just got Ruger All-Weather Hawkeye in 25-06 and began trying different factory ammo. All shot on the same plane vertically, but this is how the groups went:
...................................Group............ Position
100gr Rem Core-Lokt....... 1.25"............. .5" Left of Center
120gr Win PXP.............. .85" .............. .5" Right of Center
115 Fed. Partition ......... .53" ............... 1" Right of Center
100 Barnes TTSX .......... .42" .............. 2.5" Right of Center

Groups were 4 shots and I left the rifle cool to ambient temp. between groups. I've read about rifles that will horizontally string out individual shots of a group. And I've personally seen how my other rifles will space good groups out vertically when bullet weights change or when powder weights change with the same bullet. But I've never seen or heard of good groups being spaced out horizontally like that. Is it common? What causes it?

I am assuming 100yds as the range. Clearly from the group sizes you can shoot so we can eliminate technique for a start.

My 30-06 prints on the POA with 180gr. SGK but with the same load and Accubonds will print 3" right an 4" low. So I do have experience of bullets printing in different places.

I would offer the following as possible reasons;

- Your seating depths would have been different due to the ogive differing in profile. So the jump would have varied. You could try knocking the bullets out a little with a kinetic hammer and them seating them such that you end up with the identical jump.
- It is possible that you action screws are loose and that after every heating and cooling cycle (read after every group) the action may be moving.
- If that was the sequence of the groups then there is a shift from left to right. Was there any wind blowing on the day and picking up in intensity from left to right?
- You could be canting the rifle.

 

[helotaxi]

If I'm understanding correctly you're worried about POI shifting between groups using different bullets? It happens. It's perfectly normal. Don't worry about it.

 

[Tim the student]

Helotaxi nailed it, IMO.

 

[Roadkill]

If I'm understanding correctly you're worried about POI shifting between groups using different bullets? It happens. It's perfectly normal. Don't worry about it.

Absolutely correct. I was out last week with a Winchester Mod 70. At 100 yds a five round group was centered 1" high, same load with another bullet was 2" left low, another was 2" left high. Same powder load, same weight bullet. Two were boat tail, one was flat based and soft point. I'm hunting with the center high group.

 

[Caliper_Mi]

Were the groups shot in the order you listed them? Could be a problem with the sight or scope walking. (I'm assminig the wind wasn't blowing) If possible, try heading back to the range in similar weather and shoot groups with the ammo in the opposite order. See if groups continue to drift right indicating an equipment problem or if they keep the same POI as before indicating zero change with different ammo.

 

[travisd]

So? I don't see what the problem is. Those are great groups. Adjust your scope if you decide to shoot a different ammo. Different ammo isn't going to shoot to exactly the same place.

 

[BluegrassDan]

Different brands will have different POI. Only worry is if there is stringing with the same ammo shot to shot.

 

[sage5907]

If you change any ingredient in the cartridge components you shouldn't be surprised to get a different point of impact. Why would you expect the point of impact to remain the same? On the other hand, if each cartridge is identical in components and you are getting horizontal stringing I would say you're letting the rifle walk horizontally on the rest. Shooter

 

[Ky Larry]

Bullets of the same weight from different manufactuers are of different lengths, shapes, center of balance, and composition. They won't shoot to the same P.O.I.