Author Topic: Does Barnes TSX ammo really give rainbow trajectory?  (Read 874 times)

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Offline kernman

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Does Barnes TSX ammo really give rainbow trajectory?
« on: December 16, 2008, 02:56:52 AM »
You have heard of "rainbow trajectory?"
I had heard this about Barnes TSX factory ammo, and I'm beginning to believe it.
I'm new to shooting with scopes, so I'm no expert. Can any body here can shed some light?
I recently range tested some Corbon, 150-grain, TSX copper in my 30 30 Marlin 336 W.
I got 1 inch groups at 25 yards, about 2 inches high. At 50 yards, it climbed to 3 inches high.
At 75 yard the shots started stringing vertically, up, up and away, until they were hitting above the paper.
Has anyone experinced this? Is it shooter error, or is it extreme rainbow trajectory?

Offline GatCat

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Re: Does Barnes TSX ammo really give rainbow trajectory?
« Reply #1 on: December 16, 2008, 03:51:53 AM »
I don't have a ballistics chart in front of me, but, if you were right on at 25 yards ( scope or irons ), the bullet will continue to rise a bit, probably reaching a high of maybe 3" somewhere around 150 yards or so, then it will start dropping down toward point of aim. Re-reading your post,you were about 2" high at 25 yards, that is TOO HIGH. Bring it down to "right on" at 25 yards. Something is wrong if your shots started stringing "up, up and away". Perhaps the barrel started overheating, throwing the shots. Perhaps you either held or supported the forearm differently??
Give your Marlin a checkout, making sure screws are tight, scope base and rings are tight, etc. Shoot slowly from the bench. Get a Zero at 25 yards, let the barrel cool, and try again at 100 yards.
Mark

Offline mannyrock

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Re: Does Barnes TSX ammo really give rainbow trajectory?
« Reply #2 on: December 16, 2008, 11:56:49 AM »

  I totally agree with the prior post.  If the shots are flying up up and away, it is definitely not the ammunition.

  I had a similar experience with my brother. He bought a brand new Handi-Rifle in .30-06.  He never kills game past 100 yards, so to sight in, he always starts at 50 yards.  He complained to me that shooting from the bench, his rifle would put two rounds very close to each other at 50 yards (often touching), but that after that, the shots starting going up up and away with every subsequent shot, until they were hitting as high as 6 inches high at 50 yards.

   I went down to his farm, and watched him shoot, and the rifle performed exactly as he said.  I then took the rifle from him.  Waited 15 minutes, and started over. 

    I fired the first shot, and waited 3 minutes.  He said, "What in the world are you doing?"  I said, "I'm letting the barrel cool. Ever heard of it?"

    After 3 minutes, I fired the second shot.  It touched the first shot. 

    I waited another 3 minutes, and fired a third shot.  It was within 1/8th of an inch of the second shot.  I waited another 3 minutes and fired, waited another three minutes and fired, waiting another 3 minutes and fired. 

   In the end, I had six holes, 5 of which were touching each other.

   I then told him, "The 30-06 is a high pressure, high power cartridge, that generates alot of heat.  You can't shoot it as if you were cycling .38 special loads thru a .357 lever action carbine, or it will never group.  This is generally true of all modern big game rounds, and most of the ultra fast varmint rounds."

   Hope this helps.

Mannyrock

Offline kernman

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Re: Does Barnes TSX ammo really give rainbow trajectory?
« Reply #3 on: December 21, 2008, 04:16:32 AM »
Thank you both for your thoughtful replies.

Mannyrock,

Next time I will zero it at 25 yards as you suggest. Then it should stay in the black, at 100 yards. If not I can investigate shooter error.

I heard that if you are on the bullseye at 25 yds, you can stop there. You don't need to waste any more ammo! That's because, with decent ammo, if you are on bullseye at 25 yds, you shouldn't be more than 3 inches high at 100. If you are higher, blame shooter error.

I will review my bench technique. (Now that I think of it, I may have changed the scope setting from 3 x, for the 25-yd. shots, to 6 x , for the 75-yd. shots. (Nikon Prostaff, 3x9) But i didn't take notes on this, so I can't remember for sure).

I am learning that when testing ammo, you need to be precise, and take notes of any and all changes you make, no matter how insignificant they might seem at the time.

Mannyrock,

I hear you about letting the barrel cool. Generally I do this; I work very slowly when I am bench shooting. I will make sure to wait at least 3 minutes between shots.

Again thanks for the replies, and please add anything else you can think of!


Kernman