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Old December 26, 2013, 05:25 PM   #1
std7mag
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7mm Rem Mag AI???

Would anybody know if there was ever a 7mm Rem Magnum in the Ackley Improved configuration???

If so, any load data???

Just a thought...


Thanks!!!
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Old December 26, 2013, 06:45 PM   #2
Brian Pfleuger
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I have seen references to a 7mm AI Magnum. I assumed it was based on the 7mm Rem Mag but I don't know. As with most AIs, you're usually on your own for data unless it's a popular version. Conventional wisdom is to start at the parent cartridge max and work up, usually 3-5%.
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Old December 26, 2013, 06:49 PM   #3
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A 7mm Rem Mag AI, or you could just go with the 7mmSTW. Probably almost identical performance wise.
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Old December 26, 2013, 08:54 PM   #4
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The standard 7mm Rem Mag is so good that handloading can really make it sing.

Hodgdon has load data for a 180 gr projectile over 2900 fps. That will reach out and smack something. The BC and sectional density of those long skinny bullets really shine over the 30 caliber offerings.

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Old December 26, 2013, 09:30 PM   #5
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Very little difference between the 7MM/STW and the Weatherby 7MM Mag, if I had to choose I would go with the Weatherby because I think ammunition availablity would be more plentiful for the Weatherby.. William
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Old December 26, 2013, 09:52 PM   #6
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You can AI the 7mag case and work up using 7mag data to start with. I hate to compare but you have a case that's pretty close to the 7RemAI in the 7Wby Mag case.

I've always build the AI's on standard case not that I haven't wanted to build on a belted case just trying to find the right one.
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Old December 26, 2013, 10:12 PM   #7
reynolds357
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I retired my two STW's when the RUM came out. The STW has the WBY and the Rem handily whipped. The Rum has the STW handily whipped.
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Old December 27, 2013, 10:15 AM   #8
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Jimro, what 28 caliber bullet has a BC higher than Sierra's 30 caliber 240-gr. HPMK's .711 G1 value as tested by velocity and time of flight, not shape calculations?

Std7mag, while the AI'd version of the 7mm Rem Mag will shoot a given bullet out faster, note it'll also have a shorter barrel life. When the 7 Rem Mag was popular in long range matches, those getting best scores with it rebarreled at around 800 rounds.
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Old December 27, 2013, 02:32 PM   #9
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This is Berger new 7mm bullet should be out this coming springs for all the 7mm fans.

Berger 7mm 195 gr EOL Hybrid Hunting bullet.

It has an estimated averaged G1 BC of .794 and a G7 BC of .406. For those who understand such things this bullet has a G7 form factor of .850. For those who don't know what that means it means that this bullet is the slickest (in terms of velocity retention) on the planet.
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Old December 27, 2013, 03:53 PM   #10
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Bart B.,

Ok, unless this source is lying then the 176 Cauterucio VLD has a higher BC from actual data than the 30 cal 240 SMK. http://forum.snipershide.com/snipers...sm-7-08-a.html
Quote:
176 Cauterucio 66.5 MagPro 2900 23.5 MOA to 1,000 yds.

176 Cauterucio 61.1 RL22 2815 25.50 MOA to 1,000 yds.

All loads were worked up at 1,000 ASL during the summer with temps up to 100F in Texas.
By doing the backwards ballistics calculations, that is a BC over 0.850 G1.

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Old December 28, 2013, 11:15 AM   #11
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Quote:
176 Cauterucio 66.5 MagPro 2900 23.5 MOA to 1,000 yds.
So it shoots greater than 235 inch groups at 1000 yards? And someone is proud of that?
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Old December 28, 2013, 02:43 PM   #12
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Mike38,

Normally folks list how much drop a given load has from a 100 yard zero for a long range load. So saying 23.5 MOA at 1k means 23.5 minutes of "up" adjustment on the scope.

Make more sense now?

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Old December 28, 2013, 07:14 PM   #13
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So Berger's new 28 caliber 195 may be king of the BC mountain. So be it. It may need a 1:7 or 1:8 twist to shoot it accurate.

But I really don't think a 28 caliber 176 grain pill has a G1 BC more than .711. But stranger things have come true.
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Old December 28, 2013, 08:48 PM   #14
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Bart B.,

The 240 SMK could have a higher BC if Sierra would change ogive profiles. Good bullets, but even the 300 Win Mag won't push them fast enough to keep up with the 250gr Lockbase bullets the 338 Lapua is tossing. Hence the reason NSWC Crane spec'd the 220 SMK for the new Mk248 Mod 0 300 win mag sniper ammo.

Bryan Litz wrote "What's wrong with 30 caliber?" and I think it is as good an explanation as any http://www.appliedballisticsllc.com/....pdf?q=bullets

Litz may have not faired too well at the F-Class nationals in Florida this year, but I trust his data.

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Old December 28, 2013, 08:57 PM   #15
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Jimro, folks have been politely getting on Sierra case regarding ogive profile updating for years. Too bad they only improved the 30 caliber Palma bullet and their 210 HPMK, I think. All the other 30's as well as 28's and many others would benefit.
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Old December 28, 2013, 11:47 PM   #16
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Bart B.,

You said it.

That 210 SMK has a higher BC than the 220 SMK. Just doesn't handle the transonic range as well. I think that might the reason that Sierra is keeping the old ogive and base geometry for the 220 and 240 SMKs.

Of course, once the "new" 210 came out, people started griping hard about seating depth because the "new" 210 wasn't as jump tolerant...

Everything is a tradeoff.

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Old December 29, 2013, 10:56 AM   #17
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Yikes, talk about thread jacked!!!



I wasn't looking to compare the 7mm Rem Mag to any other cartridge. Was just interested if anyone has heard of doing the Ackley Improved route to it.
Might be nice to get a little extra fps. and being able to use factory cartridges has it's appeal to me.
For me the cost of the Weatherby round isn't worth it.

That and I like to be a little different...

Last edited by std7mag; December 29, 2013 at 11:02 AM.
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Old December 29, 2013, 03:30 PM   #18
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Eh, just old guys chasing rabbit holes.

In terms of the AI process, you won't get much from the 7mm Rem Mag. Just like the 6.5x55 Swede, it already has a pretty decent shoulder angle and is considered "overbore."

If you did it, it wouldn't match the 7mm STW which is the 8mm Rem Mag blown out and necked down to 7mm. The STW needs an action that can handle the fulle 375 H&H cartridge length though.

In my opinion, the juice ain't worth the squeeze. I don't even see 7mm Rem Mag Improved as a special order die for reloading by RCBS. If the cost of a 7mm Weatherby is prohibitive, the cost of truly custom dies should be a red flag for you too.

If you want to hunt, the 7mm Rem Mag is more than enough for North America. If you want to shoot long range, the 7mm Rem Mag can keep up with the 300 and 338 Magnums out past 1400 meters (and further, but I don't know too many folks who have access to ranges that long).

Let us know how your project turns out. My pet load for 7mm Rem Mag is a max charge of IMR7828 under a 175gr Sierra Game King, Federal Brass and a CCI magnum rifle primer. Easy on the shoulder, groups around 3/4 of an inch from my buddie's Mauser (with a McGowen 26" barrel).

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Old December 29, 2013, 03:58 PM   #19
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7mmRM is such a good cartridge, the state should have 4 deer seasons:

1) Archery
2) muzzle loader
3) modern rifle
4) 7mmRemMag



October 2013: at 477 yards he flipped over with all 4 hooves going straight up in the air.
A guy in the truck with the windows rolled up could hear the bullet hit the buck and it sounded like a prairie dog exploding.
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Old December 29, 2013, 05:20 PM   #20
Bart B.
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Any cartridge shooting that bullet the same way into that deer would have identical results. It was the bullet that up ended that animal, not the cartridge; in my opinion.
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Old December 29, 2013, 06:37 PM   #21
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That was a 140 gr Nosler ballistic tip with 11 gr more charge than Hodgdon says.

It as only 3.5 moa off what I called 200 yard zero.

I can't seem to hit anything with more than 8moa off 200 yard zero.

Unlike really good shooters.
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Old December 29, 2013, 07:43 PM   #22
Jimro
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Clark,

Did you mean that the 477 yard shot on that deer only had 3.5 moa drop from your 200 yard zero?

If so that would be a muzzle velocity around 3,850 fps.

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Old December 29, 2013, 08:03 PM   #23
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So they would have you believe.

The trick is to be a little high at 200 yards, and then shoot targets at 475 yards and mark that range on the glow tape on the turret.

I learned my lesson from that, ballistic tables are just to get me on the paper.
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