243 Winchester Re-loading

[HartleyHunter]

Hello all

I have performed a reasonable amount of re-loading for my 223 and have just started loads for my new Sako 75 Varmint heavy barrel 243.I selected Sierra 85 grain Game King projectiles and made 7 different loads. I seated the projectile .4mm off the lands. I achieved what I felt was some good results on the targets. I then read some data that said bullets seated .1 into the lands. Does that meen .1 away from the lands or actually .1 inside the lands? I used Varget and H414 in my loads. It seemed the cooler loads 36.5 grains of Varget and 42 grains of H414 perfomed above all my other loads.

CCI Primers on all loads
Varget
35 Grains
36.5 Grains,Best Overall)
38 Grains

H414
42 Grains,Best)
43.5 Grains
44 Grains
44.5 Grains

Any tips or pointers would be appreciated, especially in regards to the projectile and the lands.

 

[2506]

That meant seated into the lands. It is called jam seating. You must be careful doing this for a couple of reasons. First you have to back off on your powder charge and work back up because with the bullet seating into the lands it will raise your pressure over bullets seated away from the lands. Second, with bullets seated into the lands if you do not shoot that round much of the time when you try to extract it the bullet will stick in the barrel and dump all the powder down in your action. I have found that most Sierra bullets like to jump, that means they like to be seated off the lands around ten thousands of an inch and some like more than that. If you want to tighten up your groups I would try different make bullets. 70 gr. Nosler ballistic tips have been very accurate for me. The Hornady V-max bullets are very accurate and then there are the Berger bullets. You did not say what you were going to use your 243 for. If it is varmint shooting those Sierra 80 gr GK's are not the bullet to use. They are made for light big game like small deer. If you want to use Sierra bullets for varmint shooting you need to use the Blitzking or Varminter bullets. If you are going to be shooting game like deer you need to step up to 95 or 100 gr bullets.
With the Rem 700 varmint 243 I use to use 46 grs IMR 4350 with the old 75 gr Nosler solid base and the 70 gr ballistic tip's that replaced them were supper accurate and would explode a ground hog. They would do 3400 fps from my rifle.

 

[BigJim]

Set you OAL to bullet manufacture specs, this will insure you are at the right pressure for the load, because of design differences Hornady, Berger, Remington, etc all have different OALs set for their bullets even though they are the same weight. General speaking most reloaders recommend 0.010 to 0.040 jump to lands. It will really depend on how your barrel was manufactured, you can find out by getting a case length gage and the dummy shell holder for each caliber and measure the exact max length for each bullet type you want to use. You may find out your chamber and throat is too long or too short to seat the bullet you want to use at the OAL you would like.

For 243 try 85 or 105 grain Hornady with H4895 powder works well for me in a Savage model 10. But each rifle is different and likes different ammo.

Jim

 

[HartleyHunter]

Thanks gents, I have been using factory ammo only in this rifle, Remington Accutip 75 Grainers until I started this project. Nearly all my shooting is Kangaroo culling but I am making these loads to see what I can get out of the rifle and I am heading out west in a few weeks to chase Goats, Pigs and Deer. On the Sierra website it states that the BC for the GameKing Projectile drops off the faster you push the bullet. How does that work

 

[Winchester69]

On the Sierra website it states that the BC for the GameKing Projectile drops off the faster you push the bullet. How does that work?

It's like magic, and no one really understands it.

My more realistic response:
If you can locate Lyman's 47th Reloading Handbook, on page 172 there is an article on the subject, Air Drag Effects and the Ballistic Coefficient. Essentially, the effect of the shock wave developed in supersonic flight varies with the velocity of the projectile.

The referenced article is authored by W. T. McDonald and T. C. Almgren. You may be able to find info with an internet search.
.