175gr TSX keyholing

bcsteve

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I was at the range this morning developing some loads for a friend who wanted 175gr TSX for his 7mm Rem Mag. When he gave me the box there was a sticker on it recommending a 1:9 twist. Remingtons have 1:9.5 twist. I figured it should be close enough. Wrong! The bullets are keyholing at 100yds, not totaly sideway but definetely yawing. I'll have to convince him that he'll have to go down to the 160gr if he wants to shoot TSX in his rifle. Anybody else had that experience with the 175gr TSX?
 
never have tried them myself in anything, but they sure are long. He will be better off with a 160 or even a 150 TSX in his 7mm
 
Yeah, I know. I'll have to convince HIM thought. Suprisingly enough though, they still grouped in about 1.5".
 
The 160 TSXs are averaging around 1/2" in my STW. Try them or boost the velocity. If you're sure they're not point on speed em up if possible.
 
The 160 TSXs are averaging around 1/2" in my STW. Try them or boost the velocity. If you're sure they're not point on speed em up if possible.

Mine too, and at crazy speeds. I can't imagine anything that would live through a direct hit from a 160 grain TSX at Rem Mag (or worse: STW) velocities :eek:
 
7mm Shooting Times Westerner. Made by Layne Simpson, writer for Shooting Times by necking down an 8mm Rem.Mag. Nosler 5th says 72gr of IMR4350 pushes a 120 Ballistic Tip 3353fps. (books most accurate load for the 120)
 
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some data suggests 3400 fps with a 140

79-80 grains RL 25 (Alliant max) gets a 160 going 3300, so yeah-3400 should be easy with the 140. Not that I've ever done it :dancingbanana:

Re: the 175, one thing I've always wondered: are long-for-weight bullets like the TSX harder to stabilize than bullets of standard (i.e. lead core) density? Or is it purely a question of mass, and length has nothing to do with it?
 
length is the problem, not the mass

a 150 grain triple shock is probably almost as long as a 175 grain Nosler Partition. It will also most likely out penetrate a 175 partition
 
I checked an online rate of twist chart and the 7mm rem mag in a rem 700 is listed as 1:9.25. I have a rem 7400 in .280 rem which has the same rate of twist. My rifle will stabilize 175 grain Hornady Interlock SP's very nicely at moderate velocity, with very nice accuracy. However I have not tried the TSX's in that grain weight. They are a really long bullet. I would think that the 160 grain TSX could do anything the 175 can, given the type of game that a 7mm rem mag is appropriate for. The high weight retension of the 160 grain TSX should make it out-penetrate a conventional jacketed 175 grain bullet.
 
You might want to try running that load through the Greenhill formula. It is available online. It will provide a mathematical estimate of the limits of bullet weight a given barrel in a prescribed rate of twist will stabilize.
 
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