7mm mag… try to push heavies or not?

[NVhunter702]

Following this thread because I have the same question.

 

[Mag_7s]

Following this thread because I have the same question.

Just have to follow bullet manufacturers recommend twist rate and you'll be good to go! If the topic piques your interest check out Applied Ballistics Mondern Advancements in Long Range Shooting by Byran Litz

 

[Balderdash]

Just have to follow bullet manufacturers recommend twist rate and you'll be good to go! If the topic piques your interest check out Applied Ballistics Mondern Advancements in Long Range Shooting by Byran Litz

It's a good start, but I haven't found it to be definitive. Sometimes bullets that shouldn't work well, do. As they say, it's more of a guideline than a policy.

For one, speed helps stabilize; so you can sometimes get away with slightly less twist on magnums. One problem with the Tikka in 7mm RM is COAL. Running heavies at 3.34 in a stock Tikka necessarily cuts down on the velocity you'll ultimately get. In an OEM 700 it's easy to run 3.5+, which helps the cause. You can get 3.6 out of a Tikka with AICS mags and different bottom metal. Such as it is, I'd still load up a few 175's and try. I've had good luck with them in several 7mm's that weren't ideally twisted.

The ELD-X's seem to do ok with less than optimal twist. I run 200's in a 1:11 Tikka 300WM at sea level no trouble.

There's a couple of easy solutions: Run 162-168's. They are still solid in the BC area, they perform great, and you have to get out there quite a way before the 175's shows a significant gain. Just about anything you can do with a 7mm at just about any distance can be done with the various 160-170's.

Have a short mag derived 7mm made in a Tikka. Yields all the COAL for heavies you can handle.

Wait for an OEM 7PRC Tikka or have a barrel so chambered screwed on. They are optimized to run 175's at 3.34. Some will no doubt be along shortly to point out that you'll do better with more COAL on the 7PRC, and they are not wrong exactly, but it ignores the reality that you won't gain enough by doing so in that cartridge to effectuate any differences in the use/utility profile.

 

[Mag_7s]

It's a good start, but I haven't found it to be definitive. Sometimes bullets that shouldn't work well, do. As they say, it's more of a guideline than a policy.

For one, speed helps stabilize; so you can sometimes get away with slightly less twist on magnums. One problem with the Tikka in 7mm RM is COAL. Running heavies at 3.34 in a stock Tikka necessarily cuts down on the velocity you'll ultimately get. In an OEM 700 it's easy to run 3.5+, which helps the cause. You can get 3.6 out of a Tikka with AICS mags and different bottom metal. Such as it is, I'd still load up a few 175's and try. I've had good luck with them in several 7mm's that weren't ideally twisted.

The ELD-X's seem to do ok with less than optimal twist. I run 200's in a 1:11 Tikka 300WM at sea level no trouble.

There's a couple of easy solutions: Run 162-168's. They are still solid in the BC area, they perform great, and you have to get out there quite a way before the 175's shows a significant gain. Just about anything you can do with a 7mm at just about any distance can be done with the various 160-170's.

Have a short mag derived 7mm made in a Tikka. Yields all the COAL for heavies you can handle.

Wait for an OEM 7PRC Tikka or have a barrel so chambered screwed on. They are optimized to run 175's at 3.34. Some will no doubt be along shortly to point out that you'll do better with more COAL on the 7PRC, and they are not wrong exactly, but it ignores the reality that you won't gain enough by doing so in that cartridge to effectuate any differences in the use/utility profile.

I can't speak on this as I have no experience running bullets less than what the recommended twist suggests. Usually the opposite, I prefer to spin a little faster than suggested. Both my 7RMs are 1/9 and shooting 168 vlds (1/10 recommended twist). COAL isn't an issue with 700 LA footprints and pushing ~3k fps.
I would guess....but I could be wrong here, that at distance (post 500 yds) and as your bullet slows down the speed in which helped stabilize, is now prematurely destabilizing the bullet.

 

[Balderdash]

I can't speak on this as I have no experience running bullets less than what the recommended twist suggests. Usually the opposite, I prefer to spin a little faster than suggested. Both my 7RMs are 1/9 and shooting 168 vlds (1/10 recommended twist). COAL isn't an issue with 700 LA footprints and pushing ~3k fps.
I would guess....but I could be wrong here, that at distance (post 500 yds) and as your bullet slows down the speed in which helped stabilize, is now prematurely destabilizing the bullet.

I like the concept of starting a build or buying process with the bullet you'd like to send and letting the fuel tank, twist, throat, etc support it. Projectile is the most important part of of the assembly.

My comment about getting away with less than ideal twist was mostly centered on those who already have a platform they don't plan or care to change and are looking for a combination to get the most from it. Partial boxes of ammo and components are sold all the time, so not much to loose in giving something a try.

 

[Mag_7s]

I like the concept of starting a build or buying process with the bullet you'd like to send and letting the fuel tank, twist, throat, etc support it. Projectile is the most important part of of the assembly.

My comment about getting away with less than ideal twist was mostly centered on those who already have a platform they don't plan or care to change and are looking for a combination to get the most from it. Partial boxes of ammo and components are sold all the time, so not much to loose in giving something a try.

I agree 100 percent of building/buying a rifle with the intended projectile and its purpose in mind. I was just concerned that folks might think...hey my rifle shoots 175gn corelock just fine why not 175 eldx or the like? And not know why they are getting poor results.
If any disrespect was perceived, that was not my intention, as I really enjoyed our conversation and condone your points.
Nick

 

[Balderdash]

I agree 100 percent of building/buying a rifle with the intended projectile and its purpose in mind. I was just concerned that folks might think...hey my rifle shoots 175gn corelock just fine why not 175 eldx or the like? And not know why they are getting poor results.
If any disrespect was perceived, that was not my intention, as I really enjoyed our conversation and condone your points.
Nick

Absolutely none was taken at all on my part. But thank you for being so courteous and respectful. It's a rarity in any setting these days.

 

[Firestone]

I've had great luck with 180vlds and retumbo, three diffrent 7mags and they all shot lights out

 

[Mag_7s]

Absolutely none was taken at all on my part. But thank you for being so courteous and respectful. It's a rarity in any setting these days.

Good to know, text is often difficult to read tone. I've seen some real bait and bash on here, due to opinions. I like to discuss ideas and opinions, but you never really know how they are being perceived.

 

[Mag_7s]

I've had great luck with 180vlds and retumbo, three diffrent 7mags and they all shot lights out

I have 2 7RMs, one loves Retumbo, the other hates it. My problem child 7RM is kinda weird, it had a polygonal rifled barrel. Once I started loading H1000, it turned the corner and became a shooter.

 

[Wrench]

My 9twist 7mm pushes a 180 hornady at 2931 and I was able to make hits to 1640yds.....for reference. My headstamp has a bit more velocity potential, but not a lot.

 

[Lwarner03]

Just have to follow bullet manufacturers recommend twist rate and you'll be good to go! If the topic piques your interest check out Applied Ballistics Mondern Advancements in Long Range Shooting by Byran Litz

+1 for this, you can also call the Berger bullet guys, they’ve been incredibly responsive, knowledgeable and helpful over the phone. Wealth of knowledge there.
I’ve had the best luck in the 160 grain range fwiw.

 

[Balderdash]

Good to know, text is often difficult to read tone. I've seen some real bait and bash on here, due to opinions. I like to discuss ideas and opinions, but you never really know how they are being perceived.

+1. Difficult to establish context.

I don't even mind a spirited back and forth and a good bit of satire. But you are correct in that things can get carried away.

 

[Mag_7s]

My 9twist 7mm pushes a 180 hornady at 2931 and I was able to make hits to 1640yds.....for reference. My headstamp has a bit more velocity potential, but not a lot.

Wrench, what is the suggested twist rate for the 180 hornady?

 

[Wrench]

Hornady says 1:8....but my experience says that's pretty conservative.

 

[Mag_7s]

Hornady says 1:8....but my experience says that's pretty conservative.

I would agree, if that was a true stability number required i wouldn't think you would be able to hit targets out to 1640.