30-06 imp and twist rate and land grooves

[Kurt L]

Hi.
not sure if this is the right pace or if I should post on target shooting area but I will try this first.
I am thinking about getting a 30-06 Ackley imp barrel made up for a 700 action I have.
Have not picked a maker on the barrel yet but this will not be till spring or so.

I plan on a 26 to 28" heavy varmint style with around 900-950 muzzle dia.
and plan to shoot 125,and 150 grain bullets and maybe 110 and or 130 but nothing over 150.
this will be a toy for shooting deer size game and smaller.and playen at the range some.

Anyway the twist rate all changes from barrel site to bullet site. like Berger says a 150 vld to use 1/14
twist others are 1/12-1/14 etc. I plan to use 150 grain or less in this and will never need or use any bullet above 150 grain.
Should I go with a 1/14 twist or a 1/13 twist for this to shoot bullets of 125,130,150?

Also any help on the lands?
I read the 3 groove are great and clean faster and stay cleaner than say 6 or 8 land barrels,
then I have read the 5r 5c etc barrels are great and shoot with less pressure etc?
thanks for any helpfull info you can toss my way.

[iiranger]

Thoughts:
#1). Mr. Ackley did not recommend, generally, the .30/'06 improved. Too little gain. He did relent for use with heaviest bullets, 180 up. This is exactly contrary to what you propose.
#2). '06 was a military project. (Surprise.) It was orginally a 220 grain round nosed bullet with best powder technology at the time, thus the 1 in 10 twist. Cartridge called .30/'03. Powder improvement (borrowed from Germany???)  allowed a new, lighter, pointed bullet at much higher velocity. Revised the .30/'06. 1 in 10 was retained. I have always noted that the .308, aka 7.62x51mm NATO, was always twisted 1 in 12 from day one.
And its bullet weight limit was 200 grains per factory. But then they sell to a mass market.
#2). You mention the VLD concept bullets. It is all a "balancing act."  As you go lighter, you must also go "lighter." Making this lighter mass into a long ballistic shape... you lose more than you gain at some point. You speak of the lighter bullets ONLY. VLD advice might not be ideal for your use.
#3). Savage went 1 in 14 with the original .250 savage to get the 3000 feet per second in the name. .250/3000. 87 grain bullet too. Most took a 100 grain bullet for game. Round nosed. I suspect you could be happy with a 1 in 14 but this is a decision to consider carefully. Twist does use up some bullet energy. Mr. Ackley said 1/3. I questioned that and he most graciously said he would check and got back to me with the wisdom of some math whizzzz. Correct. 1/3. Obviously 1 in 14 uses less than 1 in 12, etc. luck

[Kurt L]

I am not looking for extra speed I just like the case shape and looks.
I also would most likely not do any shooting over 300 yds or so at game.
I am also thinking on the 25-06 and 243 imp.

Anyway I got the twist rated down but I would like some input on
the grooves and or lands.
Is 3 groove or 5r better one way or another or just a personal thing?

[Lone Star]

...Twist does use up some bullet energy. Mr. Ackley said 1/3. I questioned that and he most graciously said he would check and got back to me with the wisdom of some math whizzzz. Correct. 1/3...

A common misconception.   Bill Davis (a noted ballistician and the developer of the VLD bullet among others) did the math on a .30-06 for American Rifleman some years ago, and he found that going from zero twist to a ten-inch twist used up about 0.35% of the energy of the bullet.  With a 150-grain bullet that's a loss of about 5 fps at the muzzle. 

Lots of folks misread the 0.35% value and thought it meant 35%.     They were wrong.  I guess that P.O. was one of them....


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[Kurt L]

thanks also Lone Star