What's the largest POI change between loads you've seen?

[AzDak42]

Normally, when I'm working up loads, changing between bullets/powder combo at most moves me a few inches around the bull. This weekend, I went from factory Hornady Super Performance, sighted perfectly 1.5" high at 100 yards to my own custom loads and was blown away by the deviation. I must have been 10" right and 9" low compared to the factory loads. I've never seen that big of a shift. (The handload: 35 Whelen - Remington new case - Fed 210M - R15 @ 55-56.5g around ~2600)

Have you folks ever seen that big of a swing in POI?

 

[PJGunner]

I have but it was between two different bullet weights in a Ruger #1 7x57. When sighted in 3" high at 100 with 140 gr. Ballistic Tips it puts the 175 gr. Hornady round nose 8" low.
The only factory .35 Whelen I've shot is just the Remington 250 gr. loads. My pet load uses the 225 gr. barnes TSX over 60.4 gr. of RL15, Reminginton brass and the Winchester WLR primer. velocity is good at 2710 FPS and accuracy is great at .50 to .75" from the bench.
I wonder if the harmonics from the factory load are just radically different from your handload causing the disparity in point of impact?
Paul B.

 

[DrMike]

I have witnessed POI shifts of in excess of twelve inches. The more normal shift seldom exceeds an inch or two. Barrel harmonics is a fascinating study.

 

[FOTIS]

12 inches plus with 458 Lott.

300 vs 500 slugs.

 

[AzDak42]

Thanks gents.. Well.. lesson learned.

My local range has target frames that get their cardboard shot to pieces. I really need to remember to either buy some huge 1000 yard targets to cover the whole thing or start closer up. Was a complete PITA trying to figure out the POI on a bullet ridden bit of backing.

After grumbling about losing out on being able to accuracy test the ammo I was working on, I had to realize. It was still a gorgeous day in AZ. I still was shooting a fun rifle. And the worst case was that I had to reload another few dozen rounds and go back to the range for another morning of shooting. Not really so bad in the grand scheme of things!

 

[R Flowers]

No, I do not remember any POI changes that dramatic, but sometimes it is amazing.

A neighbor had a pre-64 Winchester Model 70 chambered in 270 Winchester that would place Remington 130 grain ammo a good 6 inches left of Winchester 130 grain ammunition.

And I owned a Ruger Number One chambered in 338 Win Mag that shot 200 grain Hornady bullets a good 6 inches higher than 250 grain Sierra's.

You just have to check. I am amazed at the people who just go to the store and buy whatever each year before hunting and never check to if anything has changed.

 

[Elkman]

I have an old 721 that will change POI at least 5 inches between loads. Makes load development easier, when they tell you what they don't like!

 

[Oldtrader3]

My Sako Model 85, .338 Federal will move at least 3-5 inches at 100 yards on a 20 to 25 grain bullet weight change, even of the same brand, but different type construction. The rifle is nominally accurate and will hold zero well with a particular load, even year to year. So, instead of selling it, I just settled on one load and one bullet for hunting, the 210 gr Partition.

Most of my rifles are set up this way and I do not change bullets much, just rifles.

 

[SJB358]

12 inches plus with 458 Lott.

300 vs 500 slugs.

The 45-70 is the best I've seen. Zeroed with 300's, it will shoot a ft low at 100 with 400's and even lower yet with 525's. All right above or below one another though.

The 264 throws PT's way high and right. Not sure why, they are really accurate as well, just throws em differently. Usually still on a good sized target though.

 

[Oldtrader3]

I think that the bigger bores, shooting heavier bullets have more of a tendency to do this. My .45-70 did kinda the same and Scotty's did. Funny because the .340 will shoot 200, 210, 225, and 250 into the same 100 yard group. Must be muzzle velocity related to some extent but barrel harmonics are definitely strangely at play as well.

 

[FOTIS]

The 45-70 450 marlin 460 wby and 458 Win mag will do roughly the same as my Lott. The lott was the most pronounced though!