What's the maximum 7mm bullet weight for 1:9.5

[adrexco]

For the last couple years I've been hunting with a 7mm Rem Mag with a 1:9.5 twist. I've been handloading 160gr SPBT with good results. I'm looking to move to a heavier bullet, but am concerned about the slow twist rate. How can I determine what the maximum bullet weight that can be stabilized with a 1:9.5 twist rate?

Thanks for sharing your experiences!
Adrexco

 

[Gus McCrae]

Sorry for the crappy picture. I couldn't get the chart cropped. Should get you close.

 

[MudRunner2005]

168gr would be the max I would go with a 9.5" twist. You should have no problems with the Berger 168 VLD's. I'm shooting them in a 9.5" twist barrel with no problems.

 

[FEENIX]

For the last couple years I've been hunting with a 7mm Rem Mag with a 1:9.5 twist. I've been handloading 160gr SPBT with good results. I'm looking to move to a heavier bullet, but am concerned about the slow twist rate. How can I determine what the maximum bullet weight that can be stabilized with a 1:9.5 twist rate?

Thanks for sharing your experiences!
Adrexco

My friend used HSM 180gr Berger VLD in his 7MM Rem Mag (1:9.5"). According to Berger's twist rate calculator, he's SG is only marginal and recommends a 1:9" However, he harvested a bull elk in 2013 just shy of 400 yards.

 

[Dosh]

168gr would be the max I would go with a 9.5" twist. You should have no problems with the Berger 168 VLD's. I'm shooting them in a 9.5" twist barrel with no problems.

This is the same bullet I loaded for my in-law for his 7mm RM. This bullet in his rifle has killed out to 450 and is very accurate out to 800 which is the farthest he has shot it. You shouldn't have a problem, but anything heavier will perform marginally. You're only looking at 8 gr heavier and not knowing the distance you'd like to shoot, the Berger needs proper shot placement at close range.

 

[adrexco]

Thanks Guys.
I had a feeling that I wouldn't be able to move up to a 170 -180gr. Been shooting the 160gr out to 300yds with very good results. I've used up my supplies of Nosler 160gr Accubond and was considering using the 175gr Nosler AccuBond Long Range. What would you guys recommend for a long range bullet for a 1:9.5 twist?

Thanks

 

[FEENIX]

Thanks Guys.
I had a feeling that I wouldn't be able to move up to a 170 -180gr. Been shooting the 160gr out to 300yds with very good results. I've used up my supplies of Nosler 160gr Accubond and was considering using the 175gr Nosler AccuBond Long Range. What would you guys recommend for a long range bullet for a 1:9.5 twist?

Thanks

You'll need even faster twist for those LRABs!

http://www.longrangehunting.com/forums/f19/nosler-lr-accubonds-bc-testing-results-137554/

Depending on your altitude (i.e. 3300' and above), you might be able to stabilize the 180 Bergers.

 

[MudRunner2005]

Thanks Guys.
I had a feeling that I wouldn't be able to move up to a 170 -180gr. Been shooting the 160gr out to 300yds with very good results. I've used up my supplies of Nosler 160gr Accubond and was considering using the 175gr Nosler AccuBond Long Range. What would you guys recommend for a long range bullet for a 1:9.5 twist?

Thanks

Berger 168 VLD...

 

[James Bailey]

You'll need even faster twist for those LRABs!

http://www.longrangehunting.com/forums/f19/nosler-lr-accubonds-bc-testing-results-137554/

Depending on your altitude (i.e. 3300' and above), you might be able to stabilize the 180 Bergers.

Not so sure about that. My Montana Rife Company X3 shoots the factory 175 ABLRs under an inch all day. It`s a 9.5 twist. I was hoping to get it to shoot the 180 VLDs since I bought a box of em. Lol, I may have bought the wrong stuff!

 

[FEENIX]

Not so sure about that. My Montana Rife Company X3 shoots the factory 175 ABLRs under an inch all day. It`s a 9.5 twist. I was hoping to get it to shoot the 180 VLDs since I bought a box of em. Lol, I may have bought the wrong stuff!

"If" you think yours is stabilized enough for your intended purpose, that is all it matters. The link I provided was from ballistician Bryan Litz. The first paragraph below the chart states ...

"As you can see, the actual BC's can be quite close; within 1-8% of advertised if they're properly stabilized. If they're not properly stabilized (which you might not know according to groups), the BC can be 10-12% lower than advertised."

My friend shoots the HSM 180 Berger VLD in his 7MM Rem Mag with 1:9.5" and is happy with it.

Cheers!

 

[cjuve]

I use Berger's twist rate calculator to figure the best twist rates for bullets that I intend to use and try to plan accordingly. With that being said I have run bullets that according to the calculator are marginally stable. The only issue that I have noticed was that the BC seems to be affected, I use a magnetospeed to collect velocity data so my velocities were solid, zero was solid but drops were more than expected and less consistent in varying conditions. I also have another rifle in the same caliber with a faster twist rate, with nearly identical loads and the faster twist rate, drops were spot on. With consistency being the name of the game in long range you are best suited to use a bullet that is fully stable in all the conditions that you plan to shoot. A marginally stable bullet according to the calculator may be fine(no tumbling) if you limit your intended range but the further you push it out there the more likely you are to have problems. My advice would be to use the calculator and find the heaviest bullet that will remain stable in all conditions that you in to encounter.

 

[cape cove]

I know this is an old thread, but I would say it is more of a bullet length issue than a weight one. My 7mm Weatherby with the 1/10 twist will shoot real good with the 175 Hornady, but most certainly does not do good with the 168 LRX, or most other 168 gr or heaver long range bullets.

 

[cjuve]

Wow maybe nex time I will look at the date the topic was started not just "new posts"

 

[James Bailey]

Thanks

I know this is an old thread, but I would say it is more of a bullet length issue than a weight one. My 7mm Weatherby with the 1/10 twist will shoot real good with the 175 Hornady, but most certainly does not do good with the 168 LRX, or most other 168 gr or heaver long range bullets.

Thanks! That does make sense. ImI new at this so I really appreciate all the facts and advice!