High I did a down range ballistics test on my rifle today and its sighted in 4.5 high at 100yards and it is 8.5 high at 250yards and 300-350 is also 7 high and so on down. the gun at 550yards is dead on. Just wondering how come the huge rise in trajectory,none of my other rifles is like this. The gun is a 30-378 shooting 165gr moly BTPS behind 120grs of 50 BMG the gun shoots 1 inch groups at 250 yards. I have not chroned this gun with this load,according to ballistics its unbeleiveably fast.any body have a good ballistics proram to run this through and any idea whats causeing the rise at 250 yards.
How high is your scope mounted?If it is a 50mm objective it is mounted higher than normal which exagerates this situation.Your extremely high point of impact at 100 yards also exagerates this situation.Actually all of my stw's and ultramags shoot higher at 200 yards than at 100 yards but not to that extent.I do however only sight them in 2-3/4" high at 100 yards and they are about 3-1/2" high at 200 yards.I also use 42mm objectives and medium rings.
Posts: 3104 | Location: alberta,canada | Registered: 28 January 2002
MY balistic program has been real accurate for all my guns. It shows to be dead on at 550 yds with a 168 grain A-max at 3500 fps. you would have to have the following:
7" high at 100 yds. 14" 250yds 14.6" 300 yds.
300 yds would be the midpoint and then the bullet would start coming down to it's final zero at 550 yds. Personally if you are only 7" high at 300-350 I find it very hard to believe the bullet will stay up all the way to a 550 yd zero. For what it's worth I also own a 30-378 with a scope calibrated for long range shooting by precision reticles and their calculations and calibrations match this ballistic program virtually to a "T".
Posts: 2002 | Location: central wi | Registered: 13 September 2002
It is deff. your scope mounts. A gun-shop owner friend of mine came to the range las week with a .240 weth. mag. and shot 1" high at 100. Took it out to 200 and it was 4.5" high and 9 oclock. Went back to 100 and shot over the target. Went to 25 yards and shot correct or near correct. I said he had the wrong mounts. He called Weth. and they confirmed it. The light weight custom did require a different mount. Just my opinion.
I'm not sure what to say about the reply's. the gun is a sako TRG and I use sako high mounts,cause I use a 50mm bausch & lomb scope. the gun shoots awesome just really high at 250 yards. the gun was bought for long range shooting. I don't hunt with a range finder and like having a gun that is point and shoot capable out to 500 yards,with out holding over the animal. I just dont like having to aim low at close range(250 yards).
quote:Originally posted by shaydorosh@sk.sympatico.c: I don't hunt with a range finder and like having a gun that is point and shoot capable out to 500 yards,with out holding over the animal.
You are not going to find any cartridge that is going to give you a 500 yard point-blank range while maintaining a 10" diameter kill zone.
Posts: 277 | Location: McLeese Lake, B. C. Canada | Registered: 06 June 2003
As to my reply about not having a range finder I find they are not practical in a hunting situation. Example shooter class buck 160+ B&C scoring comes out on a quick trot or flat out run,or small shooting lane where you having seconds to react,get cross hairs on and shoot. I have yet to have time to use a clumsy range finder to tell me that its between 350-500 yards. Thats where having a gun that shoots flat enough to put cross hairs high on the shoulder and still hit the deer. And yes I can determine a B&C class deer at a glance under most situations. I posted originally hoping to find an honest explanation to a honest question why does a gun rise ballistically 4- 5 inches in just 100-150 yards. and yes I've seen a gun with a 6 inch rise and drop out to 600 yards a .30 cody with a 30 inch barrel shooting 165 gr ballistic tips and 108 grs imr 4831 powder.
In short, without a bunch of rhetoric, the reason you're so high at 200 is because you're already too high at 100, and as the others noted, I'm sure it's exaggerated by the high of your scope mount, which you can't change.
Now, for the rhetoric. As the others have stated. Zeroing at 500 yards isn't going to put you dead on for everything in between. It's just too far out there. You'd be better off zeroing at 200 or 300 and then getting a scope with a ballistic reticle, i.e. one with hash marks or circles for different yardages, so that you don't need to guess at your holdover. Your trajectory is going to be super flat already, so it's not like you're going to have to hold over that much. Just a thought. Good luck!
Posts: 852 | Location: Austin | Registered: 24 October 2003
First off I am not trying to flame, I know what you meant, when you said that you won't find a gun with a 500 yard PBR with a ten inch target area. I hate to differ, but my .338 lapua with a 27 inch barrel, and a nightforce mounted 2.1 inches above bore, has a MPB range of 510 yards. OF course you would have to sight it in 6.25 inches high at 100. I find this to be a big pain in the ass. So I use a mildot scope and sight it in 4 inches high at a 100. Then use first mil above center from 50-200 yards, aim dead on from 300-425, 1st dot below crosshairs for 450-525, 2nd 550-625, 3rd 650-725, after that in theory 4th mil dead on at 800, top bottom post dead on at about 880, after that use come ups. I have not shot past 750, as I have not had range access to one that long, yet. But the above is true to 750 anyways as verified by Leica 1200.
