poi change with different ammo?

[car15bill]

I have been reloading rounds for my 225 winchester recently, and had a chance to zero a new scope and try out my reloads for it.

i am putting a 55grn sp on top of 34 grains of h380 powder with cci primers. The bullets are seated to give maximum case length, which is 2.50.

I zeroed the scope with my reloads, shooting my best group yet, just over 3/4 of an inch. then i ran out of my reloaded rounds, and shot up a partial box of factory winchester ammo. i took 3 shots and could not even tell where they hit. i looked and they were printing about 5 inches left and 2 inches low.

I came home and measured some factory rounds from winchester and they all measure out at about 2.49, instead of the 2.50 that i was loading them to.

will OAL and the difference in powder(I dont know what Winchester uses for powder, or how much) cause a consisten point of impact change?

I am taking a guess and figuring on just shooting my handloads from now on?

 

[sprocket3]

I think real small changes can move POI. I changed my reloads from 55 Grain Nosler Ballistic tip to 55 Grain Sierra Blitzkings. EVERYTHING else was the same. Same amount of powder, same OAL, same cases. It moved up and the left close to 1.5 inches at 100 yards. I thought that I would be able to go back and forth without changing zero. Wrong.

 

[guntech59]

IMO, speed and bullet weight have the biggest impact on POI. Think barrel harmonics.

 

[nipprdog]

and shot up a partial box of factory winchester ammo.

Same grain?????????

For the most part, when you zero a scope on a rifle, you are commited, to that particular round.

 

[The_Hammer_Man]

+1 to what nipprdog said.

If it's a scope rifle that's zeroed for one load.. your POI WILL change if you change anything. As was previously stated by others,in this and other threads, if you change bullet type/weight things change.

What I've noticed is:

Zeroed my YHM Spectre (16" 1in7 barrel) with 75 gr Hornady TAP. My YHM has a Millet DMS 1-4x on it. Didn't want to shoot up my "good" ammo plinking/target shooting so I loaded up some mags with 62 gr. The lighter round shot flatter/lower than the heavy round.

Why'd it happen... balistics. The math is ponderous but doable. Look it up

 

[wishin]

Same grain?????????

For the most part, when you zero a scope on a rifle, you are commited, to that particular round.

Agree. Whenever I buy a new rifle I try different ammo brands and bullet weights until I get the best groups from the bench. Then I stick to that particular round within reason. Since you reload, find the sweet cartridge combination for that rifle.

 

[Al Thompson]

Even if your lot number changes on the bullets or loaded ammo, POI/POA can shift. I've seen a few rifles that were fairly immune, but many more that something as small as switching primer brands could change POI/POA.

 

[car15bill]

yep, all the same bullet weights, im sure the powder and charge was different, but, i never would hvae thought that the point of impact would go horizontally, but vertically!

oh well, guess im stuck handloading with the original load i used then, which is fine with me! not going to whine about a sporter weight barrel with a cheap bushnell banner shooting under moa!