6mm Ackley Improved question

[wildcat]

Hey everyone, I am getting ready to build a 6mm Remington Ackley Improved. I will be shooting 75grn V-MAX bullets, and I was woundering what twist you guys would recommend. I am currently thinking about a Kreiger 28" 1-14 twist 6 grove. I think this is the right choice, let me know what you guys think.

Wildcat

 

[hvyw8t]

I would go with a 1 in 12 or even a 1 in 10 for 75s. Gives you the option to shoot heavier bullets if you want or need to. I have a 6mm-284 with a 1 in 13 and anything heavier than 80 grains doesnt shoot all that well.

 

[Desert Fox]

I have an Argentine Mauser with 28" Shilen no.7 contour 10 twist chambered for 6MM Remington and this thing love the 87 grain V-Max stoked with 43 grains of IMR 4350 at around 3300 fps. I lost count of how many ground squirrels and crows bit the dust by this rifle and round combination.

 

[Buffalobob]

With a 1-10 twist but different cartridge, I was doing better than 0.5 MOA at 500yds with the 75 SMK. 75 gr bullets have a low BC and you need calm days to get very far out with them, unless of course you just enjoy the shooting which can be a lot of fun when the winds are tricky. Currently being rebarreled to a 1-8 twist for 105-107 gr bullets.

 

[Varmint Hunter]

Helpful info on the 6mmAI can be found here.
6mmAI Page

 

[bailey1474]

[ QUOTE ]
With a 1-10 twist but different cartridge, I was doing better than 0.5 MOA at 500yds with the 75 SMK. 75 gr bullets have a low BC and you need calm days to get very far out with them, unless of course you just enjoy the shooting which can be a lot of fun when the winds are tricky. Currently being rebarreled to a 1-8 twist for 105-107 gr bullets.

[/ QUOTE ]

Might want to view this as a lesson and not repeat other's mistakes.

With a cartridge like the 6mm AI, why would you want to limit yourself to light bullets???

My .243 Savage had 9.25" twist and it shot the 55 gr BT into one ragged hole @ 100 yds. On the flip side, it also shot the 105 Amax very well!!!

Go with an 8" or 9" twist so you can shoot both.

 

[LWolken]

Go with a 1-9" twist. Why would you want to limit yourself to the 75 grain bullets? I just cannot convince myself to load anything other than the vld's or the really light 55-60 gr bullets. The 55's will do well out to 400yds but then you really need the VLD's to fight the wind. What am I missing here with the middle weight bullets? I have a 1-9 243AI and by the way the Lapua brass is the best no neck turn brass for any 6mm out there. So unless you already have dies for the 6mm then you should really consider the 243 AI especially if its a short action. I'd think the 55 ers at 4000+ out of a fast twist barrel would make a bigger splat than anything the mid weights have to offer.

Lance

 

[Ballistic64]

I guess it depends on what your planning with the gun.With the twist your choosing and 75 gr bullets, 3700-3800+ velocities are very possible.Here are two very good write ups on the very subject:
http://www.6mmbr.com/gunweek021.html
http://www.6mmbr.com/gunweek042.html

I'm also in the planning stages of a 6mm AI build.Opting for a 27" 1-12 3 groove.Its also my intention to shoot 75-87 gr bullets primarily,but I'm building it strictly as my prarie dog gun.500+ yards isnt really my intended shooting distance for the gun.But with 75 gr bullets with a 1-14 twist even the author of the above article admits you really need to load to max capacities to get the 75's to stabilize.To me, in a short to mid range varmint gun, 75 gr bullets at 3700-3800 should be hang time heaven.

 

[Northman]

Rather build a 6x55 using Lapua 6.5x55 brass.. The lapua brass is very good, AND plentifull.

Its maybe 1-2 grains difference between the 6mm Rem and 6x55.

 

[Coyoter]

I guess I'll toss in my .02...
I shoot .243AI with a 1 in 14 twist, but I got that twist to shoot 55gr BTs at high velocities. Every gun but one with a twist of 1 in 10 or faster that we've tried the 75gr VMax bullets in has really liked them, so I wouldn't get a "special" twist just to accomodate them... Those VMaxs' don't seem to be overly picky.
I'll add that I've had great results from BR-2 primers and varget powder in my AI, so you may want to look into loads along that line.
Coyoter

 

[wildcat]

Well, the 6mm Ackley project has been started. I ordered my barrel and stock today. I ended up getting the Krieger Barrel with a 1-12 twist, 28" and 1.00 at the muzzle. The guys at Krieger informed me that the 1-12 would be my best bet for shooting bullets between 70 to 90 grn's. I also ordered my stock, it will be a McMillan A-5. The rifle will be used for long range squirrel killen out to 800 to 1000 yards. I will be using the 75grn V-MAX because we do not contend with too much wind out here in California, so I think it will be an excellent choice for my attended purpose with maximum Mist Effect even at long ranges. The rifle will consist of the following;
1. Remington 700 Action trued in a Speedy Gonzalez Sleeve
2. Action blue printed to a Krieger 28", 1-12 twist, 1.250 at the breech and tappered to 1.00 at the Muzzel.
3. Holland Muzzle Brake
4. McMillan A-5
5. Jewell Trigger
6. Kelby rings
7. Nightforce 12x42x56mm NXS,
I keep hearing how good this caliber is for varmint hunting at long ranges. I mean a 75grn V-MAX traveling at 3850 fps is going to be a straight shooting SOB. I will not receive my parts for about 12 weeks, and my Gun Smith said it will take him about 4 weeks to complete everything. It should be completed by July. I will let you all know how it shoots during fire forming. Thanks for the info. Wildcat.

 

[wildcat]

I forgot to ask what kind of brass should I use. I ve noticed that Lupa and Norma do not make 6mm Remington Brass, or due they. What other brass can I use. If Norma and Lupa don't make the brass I need, I will probably use Winchester. Any additional info would be great! Thanks, Wildcat.

 

[Ballistic64]

Norma 7X57 can be reworked.I bought 1000 pcs of Win. from Powder Valley and found it to be pretty uniform.

 

[uncleB]

wildcat,
I have a 6mmAI with a hart 1-12" tube, I would never do it again with anything but a 1-8" so I could shoot hi B.C. bullets. you say that you will be using it out to 1000yds on squirrels a 1-8" is better any day of the week than a 1-12". if you want come borrow mine so you dont waste your own money.
UB
P.S. if you really want to shoot medium weight bullets you are better off with a case of less capacity.