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160gr Matrix

 
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  #85  
Old 04-24-2013, 01:34 PM
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Location: South of Canada and North of Wyoming
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Re: 160gr Matrix

Using 5000' elevation and 40* in Paradise Valley yesterday, the Berger twist/stability calculator shows the 160 Matrix SF was 1.45 @ 3100 fps and the 140 VLD (Match Target?) was 1.49 @ 3300 fps (guessing) out of your 9 twist 264 WM.

I would guess your 140's are on the edge of stability in the 9 twist.
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  #86  
Old 04-24-2013, 01:52 PM
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Re: 160gr Matrix

Quote:
Originally Posted by MontanaRifleman View Post
Using 5000' elevation and 40* in Paradise Valley yesterday, the Berger twist/stability calculator shows the 160 Matrix SF was 1.45 @ 3100 fps and the 140 VLD (Match Target?) was 1.49 @ 3300 fps (guessing) out of your 9 twist 264 WM.

I would guess your 140's are on the edge of stability in the 9 twist.
Yah, lol.. I used that same calculator while waiting for my 160's to come in the mail. My numbers are 1975 elevation, and actually shoot the 140 Hunting vld's. Using those numbers and a 9 twist (@ 3135/140vld) I was getting 1.3-ish stability. With the 140's. If I recall off the top of my head, about 1.16 or 1.2-ish for the 160's.. crossed my fingers hoping that's be close enuf, but no sir... I also plugged in a bunch of numbers out of some bench-rest articles using velocities, twists & bullets they were shooting thru 6.5x284's and noted that the 8.5 twists (and their load info) was giving stability numbers on that calculator also in the 1.3 range* ..would think those boys would have good reason using 8.5 and 1.3 stability numbers to shoot 1000y matches. Compares nicely to my 140 numbers thru my 1:9.. obviously tho, not so nicely with the 160's. And my targets prove the fact*

Interesting either way* Definitely need more than 1:9 in this case for the 160's.. that info should help "some guys" anyway!
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  #87  
Old 04-24-2013, 07:56 PM
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Re: 160gr Matrix

If you are ordering a barrel, I wouldn't order anything but a 1:8 for the 160's. Looks like a real thumper in the .264 mag though. That's where the big capacity case really gets a chance to stretch it's legs!........Rich
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  #88  
Old 04-25-2013, 07:45 AM
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Location: Meridian, Idaho
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Re: 160gr Matrix

Got mine now. Plan to measure the bearing surface, sort, lot, and prep for shooting. Hopefully they are uniform enough it does not matter and I can shoot them.

If timing works out I will shoot either Friday or over the weekend. Would like to shoot some wet newpaper for side by side comparisons. Bear hunt coming up so perhaps, like others, the bullets will get used on game.
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  #89  
Old 04-25-2013, 08:40 AM
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Re: 160gr Matrix

These bullets sound awesome! I've been waiting for someone to make something bigger than a 140gr. I'm planning on getting a real big .264, something along the lines of the Allen Mag or the new 6.5mm Prometheus I read about on here recently. I was wondering though, is there a reason the 160gr isn't a rebated boat-tail like the other Matrix bullets tend to be?
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  #90  
Old 04-25-2013, 02:45 PM
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Re: 160gr Matrix

Do you guys mind giving me some advice on where you think I should start powder level wise. Right now I am shooting 56.5 Retumbo behind a 140 pill. I can shoot 57.5 but 58 is getting a little hot.

This is in the 6.5-284.

I assume the extra weight of the 160 and possibly a longer bearing surface will bring the pressure up some. I have not shot anything but 140's in it so I am unsure of what to expect.
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  #91  
Old 04-25-2013, 03:26 PM
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Re: 160gr Matrix

Quote:
Originally Posted by BrentM View Post
Do you guys mind giving me some advice on where you think I should start powder level wise. Right now I am shooting 56.5 Retumbo behind a 140 pill. I can shoot 57.5 but 58 is getting a little hot.

This is in the 6.5-284.

I assume the extra weight of the 160 and possibly a longer bearing surface will bring the pressure up some. I have not shot anything but 140's in it so I am unsure of what to expect.
You will probably be close with 3 grains less than the 140's.......Rich
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