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Which 6mm (or 6.5mm)? - How to choose.

pat fulghum

( ͡° ͜ʖ ͡°)
When looking to build a new project. I, like many people, are torn on what caliber to choose.
I like to shoot F-Open and shoot steel (prone) in the forest. I really like the 600-1000 yard range.

I wanted to share some data I gathered by plugging ballistics calculations into a simple table. I did the comparison using Berger Hybrid bullets using typical velocities.

Yes you can load hotter or milder, but I wanted to show what average Joe loads for a typical cartridge for that size/velocity. I assume that Joe can read the wind +- 3mph, so I am reporting the drift as 3MPH to show the relative drift (or error) based on size/velocity.

Some cartridges are a bit more accurate than others, but at longer range doping the wind is much more important.

Barrel life needs to be taken into account.... but smaller bullets laser beam fast through a small hole will eat barrels faster than big bullets going through big holes. A 6.5x284 and .243 might have half the life of something a little milder.


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For midrange, there isn't a big difference between the typical cartridges and the highly accurate 6br/6Dasher typically win on calm days.

So for windy days, the 284 has an edge, and that is why it rules at 1000 yard F-Class, BUT the 6.5CM and 6CM are not that much different for wind.

For elevation the 6CM/6XC/6SLR is the clear winner, especially at shorter range, because of raw speed.

Recoil is a consideration for me and I don't know if I would enjoy a 284 (or bigger) for 70 rounds a day.

So you need to figure out what kind of shooting you want to do, the recoil you want to absorb, barrel life, cost of loads, etc... So many variables to optimize.

Granted F Class is highly competitive and you want every edge you can get, but you need to have fun shooting too.

Just sharing my own data, you need to look at the different variable and optimize them for the way you want to shoot. I'm thinking a 6CM or 6-6.5x47 is right for me to be competitive at mid-range and I will go shoot 1000 yard for fun.

-- pat (aka average joe)
 
I'm in the same boat. I have discovered that my beloved .257 AI suffers greatly from fickle winds once it's stretched to 600. The difference between its most recent wind performances at 500 yd and 600 yds was very significant, while those performances of my shooting partners (using .260 Remingtons) were both substantially less affected by wind (now is the appropriate time for the collective "duh!" from the peanut gallery).
I'm leaning more toward the 6.5 x 55 (or possibly the AI version or maybe a 6.5 x 57 based on the 6 mm Remington case). I may even do a Grendel in a bolt gun if I get paranoid about barrel life.
The Dasher numbers sure look good for a 6mm option.
 
It's a pickle. I started with a 6.5x47 and really like it. Now that i have added a 6br, i'm in search of a definitive reason to shoot the 47. If terminal performance is removed from the equation, it's tough. An ultra accurate, mild recoiling 105 at 2,850 is so hard to beat at moderate ranges. Therefore, i've switched to 140's in the 47 and am searching for more speed with a different powder. Think i've found the speed, accuracy is TBD.

I do think the 6.5x47/ 6.5CM 130 load should be moved down to 2,900 on your spreadsheet. I have a much easier time getting 2,900 out of a 130 in 6.5x 47 than i do getting 2,900 from a 6br with 105s. Thanks for posting.
 
If you're not running a gas gun, I personally see no point in running a 130 in a 6.5 Creed or 47L. The 140 is the only bullet to run. I love them in my Creed. I've been to 1570 yards on an 18" plate with it so far.
 
i have found the Dasher to shoot inside the 6.5 x 47 for wind but now you can get the 115DTAC and run them at 2900 + they may be even better. jim
 
Velocity will also be where it's accurate (not potential for capacity). Not so easy to put on a table..
This is why the 6.2x284 offers nothing over a smaller 260AI.
When both are well tuned, they'll shoot about the same MV(same node), only one is using way less(and faster) powder. While a 6.5x47L capacity cannot even reach this node with the same bullet.

Pick a bullet BC, and pick a capacity and barrel length to it's advantage -but based on accuracy.
 
If you like to wildcat try the 6.5 SLR. I have done some work with one and was pleasantly surprised at the accuracy I got rather easily. Without using premium bullets also. Now most of my work was at 500/600 but I wouldn't be surprised it would work well at 1000 also.
 
6.5 SAUM..?..Pretty sure you can run a mild ( for the round ) load of a single base powder ( H-1000 ) pushing 140's at 3050ish. And if you want i believe you can crank it up ( with shortening barrel life ) to over 3200 if you choose.....Interesting option..;)
 
6.5 SAUM..?..Pretty sure you can run a mild ( for the round ) load of a single base powder ( H-1000 ) pushing 140's at 3050ish. And if you want i believe you can crank it up ( with shortening barrel life ) to over 3200 if you choose.....Interesting option..;)


Just picked an action for one......:rolleyes:

The 6.5 SAUM is definitely a hammer....
 

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