Odd Groups

[Alaska2006]

Question for the expert shooters/reloaders

Im dealing with a 300 WM that after some pains is shooting like a house a fire. Consistent groups under 0.390 at 100 yrds.
Here's what I have: running H1000 in both loads, using Fed large mag 215 primers in both loads, Norma brass both loads, (same lot powder & primers)
My Berger 215 Hybrid are running MV of 3,028 on average ( that is > 40 shots across the lab radar) dead on POI at 100 yrds
My Berger 230 OTM are running 2,827 on average (> 25 shots across the lab radar)

Both group amazingly.... except the 230s point of impact is .750 high and .500 left from the POI with the 215 Bergers.

Why do the 230's impact higher with lower MV at 100 yrds and why 1/2" left? I have shot series of 215s then 230s then back to 215s and back to 230s. confirming the grouping remains good and POI is changing between the two loads. same environmental conditions.
Today:
55 degrees, 24.77 Baro pressure, 5,147' elevation. same odd change in POI between the two loads.

 

[gohring3006]

It's not uncommon for different bullets to impact in different locations. As far has being high, it could be just a matter of the 215 having a flatter trajectory..

Or it could be where your barrel wants to put them... It's all subjective..

 

[Alaska2006]

Guess I won't be feeding the beast both without re-zeroing. I've not ran into this before. i have seen POI change vertical due to bullet weight.

 

[WildRose]

Any change in powder, charge, or bullet weight changes the harmonics of the barrel and that's most likely your issue. This is more common than uncommon.

 

[MagnumManiac]

Question for the expert shooters/reloaders

Im dealing with a 300 WM that after some pains is shooting like a house a fire. Consistent groups under 0.390 at 100 yrds.
Here's what I have: running H1000 in both loads, using Fed large mag 215 primers in both loads, Norma brass both loads, (same lot powder & primers)
My Berger 215 Hybrid are running MV of 3,028 on average ( that is > 40 shots across the lab radar) dead on POI at 100 yrds
My Berger 230 OTM are running 2,827 on average (> 25 shots across the lab radar)

Both group amazingly.... except the 230s point of impact is .750 high and .500 left from the POI with the 215 Bergers.

Why do the 230's impact higher with lower MV at 100 yrds and why 1/2" left? I have shot series of 215s then 230s then back to 215s and back to 230s. confirming the grouping remains good and POI is changing between the two loads. same environmental conditions.
Today:
55 degrees, 24.77 Baro pressure, 5,147' elevation. same odd change in POI between the two loads.

No 2 loads will exit the muzzle at the same time in the barrel whip, this is the reason for different POI hits.
Just a fact of life with most rifles.
Although, the 375 cal appears to print different bullet weights very close together, as do other big bores at slower velocities.

Cheers.
lightbulb

 

[catamountsierra]

I had a NEF Handi-rifle in .243 that shot 70gr NBTs about 7 inches higher at 100 yards than it did the 100gr Partitions. Groups were always cloverleafs at that range, but POI varied greatly with different bullet weights. I ended up trading that rifle to my mom for a good set of binoculars and she shot her first deer with it last season using the load with the Partitions.

 

[Alaska2006]

Thanks for the feedback folks. I've just not had the issue with a heavier bullet landing higher and left before.
I switch up loads in my 7STW and .280s often for coyote, deer and elk ranging from 140 gr to 168 gr and while POI does changes its always been vertical and lower with the heavier bullets.

re-zero it is when I plan to run the 230s

Thanks again