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Discussion Starter #1
I recently bought a Marlin 7mm mag, and I'm love to shoot it. So far I have shot cheaper remington, and currently shooting federal ammo out of it. I'm now intending on reloading using hornaday bullistic tip. My question is should I get hornaday brass or just use what I like? I would also like to hear others opinions of brass that they like.

John MI
 

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Brass has different case capacity so you should work up your loads from the low pressure that is recommended.

From the Hornady Handbook of Cartridge Reloading:

Case: Frontier-- It is my guess this is Hornady case but I don't know for sure.

Primer: Remington 9 1/2M

Bullet Dia: .284

Maximum C.O.L: 3.290

Max. Case Length: 2.500

Case Trim Length: 2.490

Dave



Best powder IMR 4831 for accuracy.
 

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I used to own a 7mmRM but grew tired of short case life. Belted cases headspace on the belt - in other words, when you close the bolt, the shell is held in place by the belt being pinched between the bolt face and the chamber mouth while non-belted rimless cases headspace on the shoulder. Belted cases permit more brass flow when fired, meaning the cases will stretch faster than ones that headspace on the shoulder. That requires more frequent trimming and will result in weakening of the cases just above the belt. A bright ring can appear on the cases after perhaps two or three firings, indicating that the case is about to separate. Setting up your sizing die to resize the case j-u-s-t enough will lengthen case life.

Make yourself a case-stretch inspection tool by straightening a large paper clip and cutting one end so it forms a hook. Extend that down into the cases and feel for a depression around the case 1/16" to 1/8" above the belt. A separated case can ruin a day at the range as they can be tough to remove from the chamber, not to mention the potential for gas leakage back through the action.

None of that makes the 7mmRM a bad cartridge - it is a great performer that can exhibit better accuracy than its short neck would suggest. Like a lot of belted cases, it just isn't very handloader-friendly.

Ed
 

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Trim the brass you have to the proper length, then weigh the brass to see how uniform it is. Make two lots, heavy and light, and reload them. HMB
 

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Lots of centerfire reloading experience told me to select a certain brass manufacturer, work up a load slowly and stick with it. Mixing brass and other components invite variability. I started with Federal then went to Winchester and founbd Winchester worked better for my configuration. from then on I loaded only Winchester. My primary focus was super accuracy - long distance varmit loads.

If I would chose a diferent course or components I would start at the beginning and work it up all over again.

Cheers, Dusty
 

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I load mostly Remington brass, but have also used Federal and Winchester. I DO NOT mix brass, when I am loading, I use only 1 type. I bought plenty of components just after the Big Eared, Muslim Loving Shit Head got elected. I load the Hornady SST in most calibers and it works great. I also use the Nosler Ballistic Tip and Accubond bullets. My all around powder is IMR 4350, I have gotten great loads all my rifles with that powder.

Oscar
 

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The best way to check case capacity is fill them with water and weigh the water and sort them that way. You can dry them with a little heat if you want to go to that much trouble.

Dave
 

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I'll second the IMR4831 in 7MM Mag,its a little slower than the 4350,and better alI around powder in a case that big.I've used 4350 in the 7,but it really shines in the 270,30/06 class cartridges.

D.P.Reynolds
 

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Since we have this thread going.............I've got about 5 pds of 7mm that I used to load for a Mauser if anyone is interested in buying it cheap. Jim
 

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Use the same name brand brass and I would also use a Extreme powder some thing like Varget or if you can find the loading data for IMR 8082 XBR powder for that 7mm I would try that.

8082 XBR powder is a one hole powder a lot of bench rest guys use it the Extreme powder works well in cold and also in hot weather. Like if your planning to go out west prairie dog hunting in the hot summer heat the extreme powder is the way to go...... your load will not change on you and you don't have to keep it cool.

Work up your loads slowly and just don't jump right in to a hot load if you do you maybe sorry that you did plus by working it up slowly you will find out what your rifle likes in ammo.

The bullistic tip work great but they will shoot a little high from what other bullet you have shot so you may have to a just your scope for them.

Good luck on your reloading.
 

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I use Remington brass for mine as it has the most room...I use Reloder 19 with light bullets and Reloder 22 for 160gr and heavier...I really like the 7mm's reach but dont care for the way it destroys meat when it strikes bone so I stay with heavy bullets most of the time
 

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You don't need to use Hornady brass to load Hornady bullets. If I am catching what you are saying, I would sort my brass by mfg., but I also would try to stick with one mfr. of brass. They all seem to have different internanal capacity. The 7 MM Remington Mag. is fairly easy to load with slow burning powders. Just start with loads reduced by about 10% and work your way up, watching for signs of pressures. You'll be fine.
 

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As was said the difference in capacity is minimal...I found a 2.1grain difference between the extremes in all the brass brands I checked...Remington held the most water by weight and Starline the least
 

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Discussion Starter #16
Thank you for all the replies so far. My intended use with this gun is bench rest long range target shooting, but also may take it to the field hunting. Sounds like my choice of brass is gonna be remington.

John MI
 

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What brand of 7 mm was that out of?

That's a pattern if I have ever seen one.

Nice shooting. I have a bunch of Norma for my 220 Swift. Not so for my old 7mm

Rick in MT
 

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As you want to use this gun for long range benchrest shooting then you ARE going to have to pay VERY strict attention to the details. Case capacity, super accurate powder drops, neck diameter and thickness which will dictate neck tension which will affect bullet release consistency. ALL of this and more will affect velocity from shot to shot. You are entering the "twilight zone". It can make you crazy and/or give you great satisfaction when you start figuring things out.

Pat
 

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My group was shot with a box stock factory Remington 700 Sendero 7 mag with a Mark 4 Leupold 4.5-14 LR/T mil-dot scope with their custom shop ballistic turret matched to the 180 Berger VLD at 2,817 fps.
 
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