Dramatic POI shift?

[AZ.noob]

In a 308 Winchester-chambered Savage, I shoot primarily 168s for practice at 200 yards. Once my skills are at a higher level, I intend on (eventually) shooting out to 1000 yards. So I've started playing around with 190 grain bullets a bit.

I expected a lower point of impact, but my groups were about two minutes low and right from my 168 grain zero. Is this common?

edit: 1:10 twist, right in the sweet spot for the heavier projectiles

 

[Tripwire]

School yourself on barrel harmonics, OCW, and what happens at the instant a bullet exits the bore.....therein is the answer you seek.

Expecting two completely different projectiles to even remotely perform the same is mostly an exercise in futility.

 

[Bear24]

could be, if it is consistent than there should be no problem. I don't have any ex going from 168's to 190's but my POI change from 178's to 155's is about 2MOA.

 

[melloyello]

Different bullet weight, powder charge, cases, primers it all can change POI. Different recipes will have a different outcome.
A 168 amax hits exactly 1" high compared to my 175smk zero at 100yds. Both are within 50fps or each other. However one load uses Varget and LC brass and the other uses RL-17 and Remington brass. Different powder, different cases, different weight bullet can change pressure and the timing of the bullet exiting the barrel. When it exits the barrel and the position of the barrel is what changes the POI.

 

[Unknown]

Even loads where EVERYTHING is the same, even velocity, can show change in POI when using two different powders, or using two different brands of the same bullet type and weight (for example 168 BTHP). all it takes is one component changing.

I have a couple of loads with 168 BTHP that share same POI, even though I used different bullets, brass, and primers. But I sure wouldn't count on it without testing it first.

 

[AZ.noob]

Thanks guys for the input, as always. Much appreciated

I didn't intend on sounding like a complete noob (maybe I picked the wrong handle...)
I expected a lower point of impact, as I said in original post. I wasn't expecting, nor am I working towards, two different loads producing identical points of impact.

What surprised me was the 2moa shift in windage with the heavier projectiles. Some may have noted that I italicized and right in the original post.

For what it's worth, I have in fact been studying barrel harmonics/internal ballistics and Optimal Charge Weights. However, if I had all the answers I wouldn't be asking a question, now would I?

The attraction to the Hide is the vast depth of knowledge, and the relatively high bar. That's why I'm here. To those who give of themselves by sharing their knowledge and experience, thank you.

 

[shooter98]

AZ, I experienced the exact same thing when I went from 147gr to 180gr ballistic tips. Here's my thread http://www.snipershide.com/shooting/snipers-hide-reloading/187746-2000-mr-180-ssts.html