Sighting in my 243 with various ammos-

[Proud Dad]

I have a 1 1/2 year old NEF 243 standard barrel on the SB2 Frame that has about 200 rounds thru it. I followed break in directions but have not done anything to it besides cleaning. I shot two deer this fall using Rem 105 gr. extended range ammo. I want to take my son coyote hunting now so I picked up some Federal V-Shok 70 gr. Nosler Ballistic Tips and some Federal Power-Shok 100 gr. soft points for deer hunting later. I started with the 100's and made a nice group but 5 inches high. After correcting and getting a nice group I tried the 70's. They were also 5 inches high so I made further corrections. Happy with that group I cleaned the gun and fired 3 fouling rounds using the old 105's to get rid of them. The first one may have been a flyer or just too low, but the second and third were one inch apart but 8 inches low! (I guess that is consistent). I know different ammo behaves differently and lighter bullets fly faster and fall less but 8 inches seems like a lot!  What do you guys think?

[cpj]

Proud Dad,
welome to GBO!
 You would think that a heavy bullet would shoot low because of the weight of the bullet (and it would, more than likely) but different bullet weights also cause the barrel to vibrate different, hence a different point of impact. Some one alot smarter than me should be along soon to explain my therory better or to discredit all together.

[Proud Dad]

I forgot to mention, all targets were at 100 yards and I am trying to end up with the group 1.5 inches high.

[stimpylu32]

Proud dad

Not sure if i understand the problem . The rifle was sighted in with the 105s right.

Then you went to the 100s that were 5 in. high , then the 70s that were another 5 in. high for a total of 10 in. high total . If i am correct so far .

I take it that you ajusted the scope up 5 in. then another 5 in. right ?

Then you went back to the 105s and they were shooting 8 in. low after cleaning .

That means that the rifle is shooting the 105s about 2 in, high over all after cleaning which is not uncommon for my handi 's , go back to the 70s and see where they shoot .

[Proud Dad]

Stimplu32,
Thanks for the reply. Actually it was 9.5 inches lower if you count the 1.5 inches above center for 100 yards. But I can see how the cleaning can affect the line. Anyway the main question remains is it normal for the Federal 100's to shoot 5 inches higher than the Rem 105's( which seemed close to the Rem cor-lokts I had also). And then is it normal for the Federal 70 gr. noslers to shoot 5 inches higher than the fed 100's and 10 higher than the Rem 105's at 100 yards.

[bladerunner]

different manufacturers load with different charges,so,yes,it's pretty common to get a different point of impact with different brands.....in my rifle,federal fusion 95 grains actually shoot about 8 inches LOWER than winchester 100 grains do........someone said that the hotter loads can actually hit LOWER due to the fact that they are out of the barrel faster and recoil doesn't affect them as much......you're better off finding the load that groups the best out of YOUR handi and sticking with it

hope all that helped ya  

[McLernon]

I think one of the most important variables when you change ammo is the effect that recoil has on POI. Heavier bullets at the same velocity recoil more tending to move the POI up assuming the same ballistic coefficient. But most heavier bullets out of the same gun have a lower muzzle velocity to control presure to acceptable levels. This tends to move POI down. So the net result could theoretically be up or down; it's not a simple matter at all. If I change ammo lot or change bullet or powder charge it means a trip to the range to sight in that particular combination.

Makes for allot of fun!

Regards

McLernon

[poncaguy]

I found with my 460 S&W Encore pistol, the 460 would shoot 8 to 10" lower at 50 yards (200 grain Corbon's) than my Corbon 454 Casull and 45 Colt +P (300 grain) would. (they grouped together)