Trajectory for 6BR Varmint Rifle?

[Headshot220]

I'm very new to the 6BR world. I'm having my first one built now for varmint hunting, coyotes mostly. I'm use to shooting a custom .220 swift or .17 Rem both have trajectory's like a laser. My question is how does the 6BR stack up? The rifle I'm having built has a 1-14 twist Barrel and I plan on shooting 75 grain V-max, I've heard a lot of good things about that round. What kind of trajectory can I expect from 0 to 600 yards with this round?

Thanks a lot!!!
John

 

[Shelley]

John

Although I've never tried 75 grain bullets in a 6mm 14" twist, Shilen's web site says that a 14 twist is good up to 70 grains and a 13 twist is good up to 75 grains. I'd darn sure try a 75 grain in the 14 twist though because I love to experiment. Surely someone will jump in here that has tried that combination. I've probably got twenty 14 twist 6mm barrels for my bench guns but I tend to shoot 66gr flat base bullets in those guns.

But then, with a 14 twist you can get some of the best bullets in the world in the 68 to 70 grain range.Virtually any of the benchrest bullet makers can supply you with extremely accurate bullets in that range. Good bullets do make a big difference in accuracy. There are a few BR bulletmakers who make boat tail bullets if you feel a need for a boat tail.

I think if it were me, and if it isn't too late, I'd order the barrel in a 13 twist. That would be great for both 66gr or 75gr.

So far as your trajectory question... I haven't a clue. In my game, short range benchrest, trajectory is a non issue, sorry to be useless on that.

Shelley

 

[SnakeEye]

Most likely the 75 will shoot well in the 14 tw. If I was you I would go for a 12 tw that will allow you to shoot 55 gr. - 90 gr. bullets. For shooting varmints out to 600 yds the 75 - 87 gr VMax's are very hard to beat.
SnakeEye
Varmints For Fun

 

[expiper]

http://www.eskimo.com/~jbm/ballistics/traj/traj.html
Here is a link to a ballistic calculator that is pretty good..just plug in the numbers and that Swift wont be the only lazer you ever shoot...Roger

 

[Headshot220]

I heard a lot about how the 1-12 or 1-13 would be a better twist for that 75 grain bullet, but my smith says he has a 75 grain load that will "git'er done" in that 1-14 barrel. and what a great sight for trajectory charts roger.

Thanks for all the help!
John

 

[Forum Boss]

There is a Ballistics page right here at 6mmBR.com:

http://www.6mmbr.com/ballistics.html

You'll find a link to the online JBM program, and you can also download the PointBlank software, and the Pejsa program, which works as an Excel spreadsheet.

PointBlank, though FREE, is a very full-featured program and a good predictor of bullet trajectory. The Pejsa program, we've found, is even better when you are using high BC VLD bullets.

Download either, plug in your bullet weight, BC and velocity and the programs will chart trajectory. You can find bullet BCs in our Bullet Comparator page: http://www.6mmbr.com/bullets.html

You'll find BOTH these pages one click away on the left tool bar!!

 

[Stysh]

Headshot

As you are going to be using your 6BR for hunting, you will likely be using hunting bullets, rather than benchrest/target bullets? If you intend to use any of the plastic tipped type of bullets,i.e. Nosler Ballistic Tips, Hornady VMaxes, Sierra BlitzKings) keep in mind that due to their longer length compared to "regular" design bullets of the same weight, these bullets require more rotation,more twist &/or velocity) to stabilize properly. As the 6BR is not really a maximum velocity cartridge, you may not be able to make up for insufficient twist with very high velocity. I would strongly recommend that you decide which bullet,s) you will probably use, and then call the Tech guys at the bulletmaker and discuss the required twist for your application.

CraigK

 

[alintx]

Most of mine are 13.5 tw, and shoot 68s and 70s extremely well. Have one with a 7tw Krieger that shoots 80blitz and 85 hpbt really well, but will blow up a75 sierra occasionally. Think my favorite for way out there is the blitz. Super accurate, and still gets pieces up in the air. A ten twist might be a good compromise for all weights tho

 

[ChrisNZ]

Not often you see a 19 yr old thread revived. My advice is always err to a faster twist, gives you far more options. The concept that fast twists can't shoot lighter bullets is plain wrong.

 

[snert]

The title didnt grab me, it was the names of guys I never saw before that pulled me in...

 

[Webster]

I'm very new to the 6BR world. I'm having my first one built now for varmint hunting, coyotes mostly. I'm use to shooting a custom .220 swift or .17 Rem both have trajectory's like a laser. My question is how does the 6BR stack up? The rifle I'm having built has a 1-14 twist Barrel and I plan on shooting 75 grain V-max, I've heard a lot of good things about that round. What kind of trajectory can I expect from 0 to 600 yards with this round?

Thanks a lot!!!
John

My 14 TW 6BR doesn't shoot 75 gr bullets in small groups. 55 to 68 gr are the best. I think it was a 70 gr Sierra that shot decent but not great. Serious BR shooters shoot 68 gr. 13.5 or 14 twist. The 60 gr Sierra Varminter is an extremly accurate bullet. If you want want to shoot 70 to 90 gr you need a faster twist. I think it's the Sierra or Berger manual that gives some recommended twist for various bullets. One of the manuals recommends something like a 12 twist for 68 gr. Doesn't make sense no competitive shooter shoots anything other than 13.5 or 14?

 

[ChrisNZ]

If does if the bullets mentioned in the manuals are boat tails. The twist rate is largely determined by the -length- of the bullet, not the weight