problem with scope/gun/me? Need advice...

[noob_shooter]

Yes, I'm still a noob. Here is my problem. I trashed my original target so i drew one similiar to it. I own 2 Savage 93R17's. One BTVS and one in standard barrel. Both with accutrigger. Sighted both using hornady VMAX. Super accurate.

I figured shooting the CCI 20grain FMJ will just change the point of impact slightly lower since the buller is heavier. Instead it hit upper right. Shot it with both guns and about the same result. Loaded some VMAX and bullseye. BOTH sighted at 25yds. everytime. ***? I used Hornady's trajectory calculator and i expected to see around the same results, but i was surprised...I'm gonna try to sight @ 25yd using the FMJ and then load both guns with the VMAX rounds and see what happens..

Scopes: Bushnell trophy 3-9-40, Tasco 4-14-40 1.5" from center of scope to top of barrel.

 

[ugaarguy]

25 yards is a point blank zero for the lighter bullets. Think of the trajectory arc. Your muzzle sits below the zero plane. The rounds climb to the zero plane (point blank zero), keep climbing, reach maximum height of trajectory, and then descend back to the zero plane at whatever range you've zeroed the rifle.

The 20 grain rounds have a greater arc than the 17 grain rounds for the same zero distance (the lighter bullets shoot flatter). Because of this, the heavier bullets have a closer point blank zero than the lighter ones. At the PBZ of the 17 grain rounds, the 20 grain rounds have already crossed the zero plane, and are climbing toward max height of trajectory.

 

[Art Eatman]

It's common for a different bullet to have a POI a tad off to the side of another. Different vibration frequency of the barrel.

A heavier bullet will commonly impact a bit higher on the target than for a lighter bullet and a given zero. A smidgen more recoil, raising the muzzle a skosh. It's more noticeable with handguns.

 

[rangerruck]

both dudes above are totally right; not only the above stuff, but with the heavier bullet, you will also get a slightly larger harmonic whip, which will totally throw the bullet up a bit more. By the way, I say with a bit of aneqdotal evidence, that the 20 grain will make a smaller group in your rifle, being a savage. Have you shot both for multiple groups yet, to see which is smaller for you? If not and you plan on doing, please come back and give us your results. I think Savage, by will or not, makes a better rifle for the 20 grainers, than the 17's.

 

[trstafford]

Velocity

One other item which affects impact difference is velocity. Heavier bullets travel at a slower velocity which means it is in the barrel for a longer period of time, be it ever so small to us it only takes a minute amount of movement to make a change in impact and even a 22 has some upward recoil. This is usually more noticeable in a pistol.

 

[rcmodel]

slightly larger harmonic whip, which will totally throw the bullet up a bit more.

"Harmonic whip" could throw the bullet in any of 360 degrees.

A round barrel can "whip" in any direction it wants too.
Not just up.

Thats why changing bullets can move the group in any direction.

rc

 

[gbran]

For me, sighting in a 25 yds, just assures me I'm gonna be managable at 100yds. I fine tune my zero at 100 yds or whatever distance I want a true zero.

Think of zeroing as a 2 step process where 25yds is step one and 100yds is step two.

 

[MrCleanOK]

Noob Shooter,

As everybody else has said, what you're experiencing is completely normal. That's why most folks will pick a load that groups well in a particular rifle for a particular purpose, zero the optics for that load, and stick with that combination only.

 

[noob_shooter]

thanks a lot guys.. for a moment, i thought my rifles crapped out on me...

again, thanks

 

[Sunray]

As with any rimfire, you have to try a box of as many brands as you can to find the ammo your rifle shoots best. The price of said ammo means nothing either. And you'll have to do it for both rifles. Rimfires are just like that.
Trajectory calculator's don't tell you what ammo your rifle(s) will shoot best.
That being said, it's not unusual for different brands and bullet weights to give you a different POI. Changing ammo or bullet weight, with any factory ammo, including factory centrefire, means you have to sight in again.

 

[CZ223]

I am not trying to be critical but,

if you are getting 4 inch plus groups at 100 yards, something is very wrong. Maybe I have misread your target but either of those rifles are capable of right around 1MOA or better with several brands of ammo. My BTVS will put 5 shots in one inch at 100 and I have seen several that will do groups half that size. I would check your scope mounts first and look at the scope itself after that.

 

[rangerruck]

Well... like he says, he is a shooting newb. Practice your breathing techniques, body position, shoulder holding, and trigger pull, before deciding the weapon is crap. With the 17, if you do the above stuff pretty good, you should get your groups at 100 yds, down below 2 inches. Considering all else on the rifle is okay. Once there, then you need to do stuff like, sand out the bbl channel, to make sure it has no sticking points, do a trigger job; you can do one on the accutrigger, just go over to rimfirecentral.com, and check the savage threads.
check and tighten all screws on the scopemounts/rings, maybe use a little loctite. Maybe bed the action; first, with just aluminum tape, a few layers of tape, in the sides, and bottom of the stock, where the receiver fits in, just to make it extra snug. stuff like that. But he is right, this should shoot 1 inch or smaller groups at 100, while you wear a blindfold.