What bullet weight for 7 rem mag?

[oldgrowth]

Hi everybody, I am getting a new rifle chambered in 7 remington mag to use for a long range hunting rifle. It also will be used for target shooting out to 1000 yards. I plan on using berger bullets because they have worked so well in my 30-06.If you had to choose one bullet, what weight would it be? I am thinking about going with the 180 grain to help buck the wind. I know i will loose a little velocity but i am hoping the b.c will make up for that when it gets out there at distance. What do you guys think?

 

[Justin Crossley]

What length will the barrel be?

 

[16Bore]

I believe Hornady is going to start making the 162 Amax again.

 

[oldgrowth]

I believe it is a 24". The rifle is a Tikka light weight. I know it is not ideal for long range but i wanted a lighter more weather resistant rifle than my 06. I do want to see just how far i can get it to shoot.

 

[Travis Bertrand]

Do you know the twist of the barrel?

 

[Sam Millard]

Twist rate should be 9.5. The Berger 180s shoot very well and are deadly on critters, but you may not be able to push them fast enough out of a 24" barrel to realize the BC advantage over the 168s. The 168 VLDs will have no problem shooting to 1k and beyond.

As mentioned, Hornady appears to be resuming production of the 162 AMAX. I have shot that bullet out to 1300 yards with great accuracy and killed with it from 125 yards to 700+ at 7WSM velocity (2950).

 

[Broz]

Probably the 168 will be best for the 24" tube. But I am like you and would have to try the 180 to see. The 24" should only run 40 to 50 fps under 26's. Its all about range and BC as far as drift is concerned. But the 180 will speak louder when it gets there at any distance considered long range.

Jeff

 

[oldgrowth]

Thanks for the responses guys. This makes me wonder, what velocity i should expect to see from each weight. I am purely guessing, but i am thinking in the neighborhood of 2900 for the 168's and 2700 for the 180's? I have yet to pick up a berger reloading manual.

 

[oldgrowth]

It looks like i would have to push the 180 grain bullet to 2850 fps to beat out the 168, assuming the 168 is moving at 2900 fps. I don't have any experience with the 7mm so i am just making up #'s for velocity. But it looks like the 168's will be better suited for my purposes if i can't get the 180's moving at 2850fps.

 

[Sam Millard]

You should get ~3000 with H1000/168s, even from a 24" tube.

 

[16Bore]

Check Hodgdon and Noslers site for data.

 

[bigfish b.c]

i get 3250 out of my 7mmstw with 168 & did not see a big enough diff in the 180gr vld to shoot them + i did notice a fair bit more kick to the 180gr though think i was getting about 3050fps out of the 180s,both great bullets though.

 

[Broz]

12 gr of bullet weight will slow the 180, but not that much. The BC will pay off at some point in wind and not all that far out if both are loaded to equal pressure. The energy and SD gains will show up much sooner.

Jeff

 

[oldgrowth]

Okay, i was playing with #'s using JBM's calculator and it seems like the 180 grain is the way to go as long as the velocity difference is not more than 150 fps between the 168 and 180. It looks like the heavier bullet will drop more, but bucks the wind better and arrives with more energy. Jeff, do you think i should be able to keep the muzzle velocity high enough to realize the advantage? Please bear with me. Thanks

 

[Broz]

Jeff, do you think i should be able to keep the muzzle velocity high enough to realize the advantage? Please bear with me. Thanks

It all depends on how far you want to shoot. There will be a point where the 180 will become the faster of the two because a Higher BC bullet retains its velocity longer and also slows at a lesser rate. If you are dialing for elevation I would always go with the bullet with less wind drift and more energy for the longest pokes. They will be the easiest to place on your point of aim and do the most damage. That is as long as the rifle shoots them as well.

Jeff

 

[Broz]

Something from Bryan Lintz on the subject.

"It's not a realistic comparison because you're talking about different chamber pressures. For example, it takes more pressure to get the 168 to 2940 fps than it does to get the 180 to 2800. Given equal chamber pressure (as the 180 at 2800), the 168 only achieves 2898 fps and the 180 is superior in terms of wind deflection.

Now if you jack the 168 up to 2940 fps to match the 180, the chamber pressure is equal to the 180 at 2840 fps, and the 180 is ahead again.

Nailing down the expected muzzle velocity of different weight bullets is an important part of any 'fair' ballistic analysis. It's hard to do because the chamber pressure assumption isn't always hard-and-fast. Sometimes the load isn't accurate at a certain chamber pressure and you're forced above or below the 'theoretical' velocity.

I hope this clarifies more than it confuses

-Bryan"

As you can see in Bryan's quote, with equal chamber pressure the 168 and the 180 are only about 100 fps apart.

Jeff

 

[Sam Millard]

The chamber pressure theory is sound, but in my experience, it's difficult to drive those 180s fast "relative" to the speed of the 168s, without running into pressure issues with the 180s.

In the end, for 1k shooting, I would pick whichever bullet shoots the best in your rifle (and you can find to buy ). With the 168 @ 3000 fps and the 180 @ 2900 fps, the 168 requires .75 MOA less elevation correction and .5 MOA more windage correction...all other things being equal...in theory. I would concentrate more on wind reading and holding .5 MOA @ 1000 yards than minute ballistic advantages of similar bullets. JMO!

Shoot more, stress less...

 

[oldgrowth]

It all depends on how far you want to shoot.

As far as i can! For target shooting i will try as far as my ability and the gun will take me. In a hunting senerio the range will be substantialy shorter ranges. I have an AR chambered in 6.5 grendel that i shoot out to 700 yds with. I am hoping to get to 1000 or beyond with this gun. I will be dialing for elevation and windage. Thats what i have been doing with the grendel and it has worked well so far.

Shoot more, stress less...

I like this philosiphy.

Seeing that the velocity is so close, it looks like i will have to pick up both bullets and do some testing to see which one the gun shoots better. Both bullets look like they perform great, so i am sure i will be happy shooting either one. Thanks guys. I really appreciate the responses. Now i have to decide on what scope i can afford to put on it. I am leaning strongly towards a vortex PST. My grendel is wearing a nightforce, but my wife isn't gonna like it too much if i try that again.

 

[Broz]

Sounds like you have a good plan. Shoot both and let the rifle decide. And again we are only talking 12 gr difference. I trust Sam's numbers so for 1/2 or 3/4 moa at 1000, neither would not be the deal breaker.

Sam did you happen to compare the energy at 1K ?

In the last couple years we have taken some elk with a 7 Rem and 168's as well as 180's. A couple bulls took a couple of the 168's but placement was not perfect either. The shooter wanted more umph so we switched it 180's. Only one bull with it so far and it tipped over with one well placed 180. But again this is not a good test when one bullet may have been placed better than the other. The shooter is convinced the 180 kills better. So, who am I to derail confidence. I have to agree with the practice thing. It will pay off way better than 12 gr of lead or 1/2 moa less drift at 1000. Especially when the heat is on and its time to make that one shot.

Jeff

 

[Sam Millard]

Velocity/Energy @ 1k is 1642/1005 for the 168 @ 3000fps and 1665/1107 for the 180 @ 2900fps.

Neither gives me a warm fuzzy on a hairy target @ 1k. I would prefer running that 180 on a platform that spits it out at 3000fps or more for "hunting" that far. I don't think it matters for target shooting, though. Either would work fine.

Of course, the 215/.30 or the 300/.338 is definitely the way to go when reaching out on critters over 1k