Help from reloading expert required.

[robbobsam]

Hiya Guys,

Been playing with a new load today and I just cannot fathom what is going on.

Rifle is a factory Tikka T3 Super Varmint in .243 with a 1 in 10, 20" long barrel.

87 grain VMax with 44 grains of H414
At 100yds I am getting a touching group.
At 200yds I am getting no verticle spread what so ever but 1.5 inches of horizontal spread.
I am also getting and ES and SD of 50 and 26 respectively.
Velocity is between 3075 and 3125.

87 grain VMax with 43.5 grains of H414
The group is roughly the same at 100 and 200 (.75") and the ES and SD is still about 50 and 25 respectively.
Velocity is between 3040 and 3090.
No worrying verticle spread at 100 or 200, nice groups (.75").


With the 44grain load I have had some really good shots at some extended ranges but at 200yds today when looked at closely I was getting really strange horizontal spread.

The wind all day has been less than 3mph and constant.

Is it normal for a 100yds load to be pants at 200yds then great at 700yds ??? or was the 700yd hare just a fluke ??? The evidence is that the 43.5 grains is a more consistent load and is looking better for my long range work.

Is my reasoning here correct or have I missed something ???

I expected a slightly faster velocity for a good .243 load but could the 20" barrel being having a detrimental effect on the velocity.

Your thoughts on the way forward would be appreciated.

 

[Mikecr]

Why do you provide a bunch of 100/200yd data, then ask questions about 700yds??

 

[robbobsam]

Why do you provide a bunch of 100/200yd data, then ask questions about 700yds??

I am trying to work out the best load to use. I shot a varmint at 700yds a week ago and cannot explain the horizontal spread I am now getting with the same load (44grains of H414).

I do not get the horizontal spread at when I go .5grains lower at 43.5grains @ 100 or 200 yds, what is confusing me is how do I hit a target accurately at 700yds with 44grains when the horizontal spread is so large at 200.

I am starting to think my 700yd shot was a fluke.

 

[Loner]

Your bullets are not stabilized , you are canting your rifle, your scope is canted, your scope has no
parallax adjustment. There are a lot of factors, it's not always the guns fault.

 

[robbobsam]

Your bullets are not stabilized , you are canting your rifle, your scope is canted, your scope has no
parallax adjustment. There are a lot of factors, it's not always the guns fault.

I dont think the bullets are not stabilized.

The rifle may be canted ???

The scope is mounted on the rifle, so if the rifle is canted the scope may be canted ???

The scope does have parallax.

Other than these issues is there anything else I should be looking at.

What is causing the large ES and SD ???

I use Lapua brass that is new and unfired, I use comp redding dies, I length size and chamfer to ensure eniformity, I use federal 210m's.

Any more suggestions ???

 

[BIG MO]

With an 87 grain .243 load, I would test the loads at 400-500yds and judge performance. I would say your horizontal spreads are not abnormal when you factor in small imperfections in trigger release, the rest, parallax, barrel heat, and every other element involved in breaking that perfect shot. These imperfections become more apparent at range and in most cases I would not attribute a little horizontal spread to the load.

We shot multiple rifles and loads at 1000yds this morning with great wind conditions. The vertical spread on most groups were very good. It was the horizontal spread that predominately opened the groups up.

 

[Loner]

I dont think the bullets are not stabilized.

The rifle may be canted ???

The scope is mounted on the rifle, so if the rifle is canted the scope may be canted ???

The scope does have parallax.

Other than these issues is there anything else I should be looking at.

What is causing the large ES and SD ???

I use Lapua brass that is new and unfired, I use comp redding dies, I length size and chamfer to ensure eniformity, I use federal 210m's.

Any more suggestions ???

Your scope may be mounted a little canted, or you may be canting the rifle a little while
shooting, If you have parallax it will also cause you to be off. ( I think you mean you
have a parallax adjustment though ) That small of a velocity change won't affect the
bullet drop much at those ranges but if the load is right on the edge of changing the
barrel harmonics it could cause the spread. I have a 1/2 moa load for my 243 that is
very picky about the powder charge with 4064. I have to weigh every charge as exact
as my scale will hold. .2 Grains will open the group to over an inch either way. Not
a great load by most standards.

 

[Trickymissfit]

Your scope may be mounted a little canted, or you may be canting the rifle a little while
shooting, If you have parallax it will also cause you to be off. ( I think you mean you
have a parallax adjustment though ) That small of a velocity change won't affect the
bullet drop much at those ranges but if the load is right on the edge of changing the
barrel harmonics it could cause the spread. I have a 1/2 moa load for my 243 that is
very picky about the powder charge with 4064. I have to weigh every charge as exact
as my scale will hold. .2 Grains will open the group to over an inch either way. Not
a great load by most standards.

I think I'd back the load off about .5 of a grain and see if that makes much difference, and then also seat the bullet about .003" off the lands. If things get even slightly better I'd back it off another .5 grain and seat the bullets within .0015" of the lands. Also change the primer to a Federal mag primer to help ignition while it's down one full grain of powder. I shot similar loads in a 6mm Remington, and the best it'd group was about .31" using the BTHP (I was using a 24" barrel with a 1:9.5 twist). The 20" barrel will want a little faster powder burn, so you might want to jump up one notch on the burn scale. Maybe H380
gary