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Optimum 7mm-08 twist rate

Everyone is different in what they want from a cartridge. For me, a 9.25-10 twist is perfect for my 7-08. I shoot 139-150s thru it. If I want heavier like the 160-168s, I shoot my short action 284. For the 175-180s I use my long action 284. I don't shoot much heavier than the 180s because if I need that weight bullet, I'd prefer the 30 caliber in 208-230s. This is just me. Everyone has different needs. The 7-08 is fabulous for shooting heavier bullets even up to and beyond 168s but I have that area covered personally so I prefer mine for lighter bullets.
 
VLD Pilot said:
Everyone is different in what they want from a cartridge. For me, a 9.25-10 twist is perfect for my 7-08. I shoot 139-150s thru it. If I want heavier like the 160-168s, I shoot my short action 284. For the 175-180s I use my long action 284. I don't shoot much heavier than the 180s because if I need that weight bullet, I'd prefer the 30 caliber in 208-230s. This is just me. Everyone has different needs. The 7-08 is fabulous for shooting heavier bullets even up to and beyond 168s but I have that area covered personally so I prefer mine for lighter bullets.
Click to expand...

My exact sentiments except I have more limited set of calibers, I presently shoot 140-150 in 7mm08 and maybe up to 162 in new build. Then I jump to 300wm 215 eldx. Thanks for the input.
 
How much difference is the AI 08 than a regular as for velocity? I get 2685 out of a 168 standard 7-08. Not pushing it at max but it fits mag length and it's a 22 inch barrel i think. I've been thinking about going to a 150 for better speed but I need to run some numbers and see if it will be any advantage.
 
BD1965 said:
My exact sentiments except I have more limited set of calibers, I presently shoot 140-150 in 7mm08 and maybe up to 162 in new build. Then I jump to 300wm 215 eldx. Thanks for the input.
Click to expand...
Give the Swift Scirocco 150 a try in your 7-08. They are excellent in mine.
 
Wachsmann said:
How much difference is the AI 08 than a regular as for velocity? I get 2685 out of a 168 standard 7-08. Not pushing it at max but it fits mag length and it's a 22 inch barrel i think. I've been thinking about going to a 150 for better speed but I need to run some numbers and see if it will be any advantage.
Click to expand...
No experience but from what I've read 100-150 ft./s.
 
I found that the proper twist rate for the bullets you want to shoot provides a larger tune window on powder charges. Also for game, over twisting the RPM's can cause more rapid bullet expansion, a good or bad thing? Additional RPM's do cause cup and core bullets to shed their jackets faster, this Is well known. As barrels get well worn with alligator hide throats, fire cracked badly, bullet jackets are stressed. Stressed bullet jackets MAY perform differently in expansion and accuracy, especially if the bullet is jumping to the lands.

There is another consideration, and that is what is acceptable accuracy for you. While one guy is happy with one-inch groups at 100, the next guy wants 1/4 MOA for longer-range shooting.

Spending some time on a ballistics calculator can teach you a lot about the twist rate you need for your hunting/shooting conditions.

Pressure can drop as you DECREASE your twist rate to the max limit vs a very fast twist. For example, I built a custom 7 STW, 27", Pac Nor super match, zero freebore reamer, for shooting the 140g Nosler Accubonds. 3650 fps was the accuracy node where the barrel shot in the 2's, opening up a single bullet hole using Win brass, fed 215's, and IMR 7828 with an 11 Twist, three groove barrel. 120g Barnes TTSX was doing 3900 fps, opening up a bullet hole with its groups.

In a custom 7 Mag, the only time I run into trouble with Berger 180g vld-h is in extremely cold weather with a 9T.

I have also ran the 180g Hornady ELD-M in the 9T, again with warm weather.

Again, I would urge all to invest some time on a twist rate calculator, twist for your circumstances, ONLY! Don't go 8 Twist just because it sounds cool.

For all 162-168g bullets, a 9Twist is more than adequate....run the numbers.
 
A 25", #4 contour, 7/08 AI, 9 Twist, throated for 162-168 would be awesome, have a wyatt's mag box installed on a Rem 700 to give you extra COAL.

A pard is shooting the 180g ELDM in his 7/08 AI, throated properly, with amazing accuracy with a 26" #5 contour, X caliber barrel, Gentry muzzle break, R#17, on a 8.5T Brux, smidge of powder, close to 2700 fps, Lapua brass of course.
 
Last edited:
Wachsmann said:
How much difference is the AI 08 than a regular as for velocity? I get 2685 out of a 168 standard 7-08. Not pushing it at max but it fits mag length and it's a 22 inch barrel i think. I've been thinking about going to a 150 for better speed but I need to run some numbers and see if it will be any advantage.
Click to expand...
I can push up to about 2790 with 168s out of mine. I built mine around the 140gr absolute hammer though which I run at 3003fps MV.
 
VinceMule said:
I found that the proper twist rate for the bullets you want to shoot provides a larger tune window on powder charges. Also for game, over twisting the RPM's can cause more rapid bullet expansion, a good or bad thing? Additional RPM's do cause cup and core bullets to shed their jackets faster, this Is well known. As barrels get well worn with alligator hide throats, fire cracked badly, bullet jackets are stressed. Stressed bullet jackets MAY perform differently in expansion and accuracy, especially if the bullet is jumping to the lands.

There is another consideration, and that is what is acceptable accuracy for you. While one guy is happy with one-inch groups at 100, the next guy wants 1/4 MOA for longer-range shooting.

Spending some time on a ballistics calculator can teach you a lot about the twist rate you need for your hunting/shooting conditions.

Pressure can drop as you DECREASE your twist rate to the max limit vs a very fast twist. For example, I built a custom 7 STW, 27", Pac Nor super match, zero freebore reamer, for shooting the 140g Nosler Accubonds. 3650 fps was the accuracy node where the barrel shot in the 2's, opening up a single bullet hole using Win brass, fed 215's, and IMR 7828 with an 11 Twist, three groove barrel. 120g Barnes TTSX was doing 3900 fps, opening up a bullet hole with its groups.

In a custom 7 Mag, the only time I run into trouble with Berger 180g vld-h is in extremely cold weather with a 9T.

I have also ran the 180g Hornady ELD-M in the 9T, again with warm weather.

Again, I would urge all to invest some time on a twist rate calculator, twist for your circumstances, ONLY! Don't go 8 Twist just because it sounds cool.

For all 162-168g bullets, a 9Twist is more than adequate....run the numbers.
Click to expand...
Great practical info that is not often considered including myself, definitely leaning 1:9 now! much appreciated sir
 
Have had 3 different 7/08's. Two with 1/9 and one with a 1/8.5. I feel my 1/9's are all I really need and if you are looking for a real good inexpensive bullet for deer sized game the 145 Speer SBT works great. Several powders will push it close 3000 ft/sec with great accuracy. Works for me.
 
Cape, a known deer slayer load here in SC for the 7/08's is:

130g Speer btsp or hot core if you want more penetration
42g of IMR 4895
Rem brass
Rem 9 1/2 primer
Seat the bullet no more than .005 off the lands
Tiny groups abound at 3000 fps...deer slayer load.

I just bought 5 boxes of the 145g Hot Cores, thanks for the tip
 

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