At the range today an interesting thing occured. I shot several rounds loaded with a 350 grain hornady round nose over 51 grains of reloader 7. These printed within an inch and a half at 50 yards with iron sights from my Browning high wall. I then fired several rounds of of 300 grain Hornady hollow points over 50 grains of reloader 7. All of these rounds printed high and to the right. I can understand them being high or low depending on velocity compared to the 350 grain round with one grain less powder. However why would they all print to the right. I fired another group of the 350 grain load and they were all right in the bullseye area again. Any answers out there? The reason for the two different loads were to get the different bullets to print they same so I could use the hollow point for deer and the more solid round nose for pigs and possibly black bear.

That's just the way the world works. I've had two different bullets disperse their groups horizontally several inches, and even had changes in powder changes cause a horizontal movement of grouping. Typically, this represents a reaction to uneven bedding in the forearm area, but doesn't necessarily have anything to do with the gun's accuracy potential.

You've got two different weight bullets leaving the muzzle at different points in the barrel oscillation (vibration).

[ 09-17-2002, 08:08: Message edited by: AJ300MAG ]

Pig Man,
Off topic question, how did you come by your name.
I'd like to believe that you like to hunt hogs? Pete

I've done a little hog hunting in south GA. I recently moved back home to north GA. There are a lot of hogs on the river near my Dad's property but haven't had a chance to hunt them. My cousin has a friend who hunts them with dogs then sticks them with a big knife. That's a little to much excitement for me. I'd rather sit in a tree and bushwack them. A 350 grain hornady really puts the hurt on them.

I assume ajustments in more or less powder may bring the vibration to the same point as the 350 grain round. I had good prints with 45 grains of reloader 7 and the 300 grain bullet but they were low. I thinking of trying 47 and 48 grains to see if I can get good results. Three hundred grainers clock at 1870 with 45 grains of reloader 7. The 350 should be clocking between 2000 and 2100 fps with 51 grains from the 28 inch barrel. I do know they really wack your shoulder.

What I think you're dealing with is the recoil arc of the rifle. 50 yards is pretty close to see that much deviation from barrel harmonics alone, in my opinion. If you could do a slow motion, freeze frame analysis of the rifle's recoil arc, you'd probably see that instead of rising straight up, it is rising up and torquing to the side--not a surprising thing to see in a field weight rifle shooting bullets of that weight. The bullet strikes that are hitting to the side are leaving the barrel later in the recoil arc than the faster bullets are.

Now that sounds weird, doesn't it? The 350 grain load is almost certainly the slower of the two, so it's the one that is probably leaving the barrel at a later point in the recoil arc, right?

Right, but if you correct the sights to allow the 300 grain load to hit dead center, that's going to leave the 350 grain load hitting low and left. It will hit low because it is going slower, and left because the rifle has probably come off the bags with a recoil arc favoring that direction.

Dan Newberry
green 788

Having read all the post it seems that I need to slow the 300 grain round down enough to get bullet to exit at the same point in the recoil arc. That would suggest perhaps moving the sight back one click at 45 grains or if that is to much trying one more grain of powder at a time until the best results are obtained.This would be so much easier if I were using a scope.

The right hand twist of most barrels plays a part in this phenomenon as well....ol blue

As everyone else noted it has to do with the barrel movement as the shot goes off. In my Sonchem Ballistics manual they have a nice drawing describing it . Well to make a long story short , your barrel moves it what can almost be called an eight shape as the bullet travels trough the muzzle . I would say it is just a matter of finding that load that everything is in synchro , with the 300 gr & 350 gr load . Easier said than done is'nt it

Rudie

The laws of physics come into play in any and all firearms when fired. It is a one rare rifle indeed that will print all weight bullets it fires into the same group. Those rifles do exist but are so rare it is a waist of time and reloading supplies trying to make yours do that. Barrel harmonics determine POI on the target with a given bullet weight from any given rifle. Be logical in your thinking and understand that no two rifles in the same caliber made exactly the same by the same gunsmith will produce the same results with the same load. In most cases the heavier bullet will strike lower on the target than the lighter bullet. In some cases the lighter bullet will strike lower than heavier weight bullet and the beat goes on. You could spend the rest of your life trying to find the rifle that will shoot all weight bullets it fires into the same group and fail. The rifle that will fire all it's bullets into the same group will shows that rarity immediatly. It is not something you can make your rifle do by your reloading practices, the rifle will do it or it won't on it's own.
If you limit the distance of your shots to 150 yards or less you can use two different weight bullets that print within an inch or so of each other at 100 yards. It all depends on the size of the kill zone on the animals your hunting and how well you make your shot placements with those bullets.

I'd suggest loading the bullet you want to shoot with the load that is "best" for that bullet and simply re-zero. Of course shooting for experimentation sake is fun...