Best caibre for long range f class?

caramel said:
But what kind of groups in average good shooter get in F-class... JP.
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caramel said:
Nope i do no competion whatsoever, i shoot by myself on our private range from 300 to 800 metres, when they are talking shooting MOA let say at 600 metres, that mean shooting in 6.6 inchs to keep MOA or shoot in one inch @ 600 metres... JP.:confused:
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1MOA @ 600yds = 6.283"

What you are missing is competition and the wind. F class is not about how small your groups are, it is about putting all your shots into the bull. Your rifle shoots very small groups (in calm conditions), but are they centered in the bull? What about on a windy day, with a gusting cross wind?

Looking at wind drift, let's look at a 6.5mm bullet, a 7mm bullet and a .308 bullet.

Using CanuckWR's numbers from above, we will take a 140gr Berger VLD @ 2940fps for the 6.5mm example. For 7mm, let's use a Berger 180gr VLD @ 2900fps and a Berger 185gr VLD @ 2700fps for the .308 option. If my velocity numbers are off, someone please correct me.

In a 10mph cross wind the drift at 600yds will be:

6.5mm = 20.1"
7mm = 18.8"
.308 = 26.1"

Your .308 has 30% more wind drift than the 6.5mm and 39% more than the 7mm. That means that your wind calls and corrections have to be damn near perfect in order to compete with the guys shooting the other calibres. Note that this is only a 10mph cross wind, that is a light breeze in reality. On a windy day the extra drift of the .308 is enough to put you completely off the target with a bad wind call.

These numbers are why nobody shoots .308 in F Open.


Mark
 
Thank you for explaining, now i really need to order from Wanstall that 260 barrel for my takedown... JP.
 
Strictly looking at what wins and sets records at different ranges (windage in MOA for 10 MPH at 600, 800 and 1000 yards):
  • 600 yards: 6mm 105gr VLD 3000+ fps 0.530 G1 BC (3.8, 5.4, 7.3 MOA)
  • 800 yards: 6.5mm 140gr VLD 3000+ fps 0.610 G1 BC (3.2, 4.5, 6.0 MOA)
  • 1000 yards: 7mm 180gr VLD 3000+ fps 0.680 G1 BC (2.8, 3.9, 5.2 MOA)

The trend is very clear: higher BC bullets win at longer range as wind drift error because the issue.
Note that the optimal cartridge wind drift error is around 0.5 MOA for a 1 MPH side wind estimation error. (3.8 MOA / 10, 4.5 MOA / 10, 5.2 MOA / 10).

Interestingly wind drift at 1000 yards is less of an issue with a 7mm 180gr VLD than with a 7mm 105gr VLD at 800 yards! (5.2 MOA vs 5.4 MOA of wind drift).

Alex
 
But the velocity is important to i guess a 208 Amax with a BC of .648 would drifted more because the max i can launch it is 2615 fps, but what about the same 208 Amax launch at 3000 fps from a 300 WM... JP.
 
caramel said:
But the velocity is important to i guess a 208 Amax with a BC of .648 would drifted more because the max i can launch it is 2615 fps, but what about the same 208 Amax launch at 3000 fps from a 300 WM... JP.
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I tried them at 3000 and 3100fps, the 208 Amax bullets left lots of copper in my bbl, another shooter on here had the same issues, I do not think these were designed to be pushed that hard.

FYI I have fired 400+ Matrix 210gn VLD's and have never had even a wiff of copper in the bbl.
 
caramel said:
But the velocity is important to i guess a 208 Amax with a BC of .648 would drifted more because the max i can launch it is 2615 fps, but what about the same 208 Amax launch at 3000 fps from a 300 WM... JP.
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Wind drift is solely determined by BC and velocity. You need to start using G7 referenced BC's, the G1 numbers are not that great if you want accurate comparisons. Buy Bryan Litz's book "Applied Ballistics for Long Range Shooting", it has tons of great info and accurate, tested BC data for a large number of bullets. It is worth the price for the BC test data alone. Mystic Precision used to sell the book, see if he still has any.

Now for your 208gr Amax:

@ 2615fps, 600yd wind drift = 23.1"

You are running a higher muzzle energy than I used with the 185gr @ 2700fps, your load is equivalent to the 185gr @ 2770fps. That equates to 25.1" of drift, so your 208gr is a still a better choice. More recoil, though.

If you can get that 208gr Amax to 3000fps (which is a stout 300 Win Mag load), it will have 18.7" of drift at 600yds and a lot of recoil. But it would be competitive with the 7mm's in terms of ballistic performance.


Mark
 
I've shot the barrel out of my 6.5x284 nearly. I'm planning a 7mm of some kind. 7 WSM or 7 RSAUM probably. The 6.5's are great but one cannot argue with the ballistics of the 7mm. But it still amazes me what a 6mm Dasher will do in the right hands! Awesome little cartridge.
 
Wich of a 243, 6.5 Creedmoor or a 260 would be the best barrel to order to really be competitive, the 3 are available... JP.
 
There is no replacement for displacment. Plain and simple.

The further you go, the more "true" this becomes. Can a consistent combo with lesser qualities work? absolutely BUT there is much greater demands on the shooter.

How good a driver are you?

competitive F class is all about shooting the most forgiving combo in the WINDS. That's it , that is all that needs to be understood.

It is rarely calm and that rarely sticks around for long. F class is an endurance match usually shot over 2 or more days and the weather almost always changes. The shooter that makes the fewest number of mistakes wins....

From there, the shooter compromises based on their budget, and shooting abilities.

So how much are you willing to give up?

Jerry
 
Mystic Precision said:
There is no replacement for displacment. Plain and simple.

The further you go, the more "true" this becomes. Can a consistent combo with lesser qualities work? absolutely BUT there is much greater demands on the shooter.

How good a driver are you?

competitive F class is all about shooting the most forgiving combo in the WINDS. That's it , that is all that needs to be understood.

It is rarely calm and that rarely sticks around for long. F class is an endurance match usually shot over 2 or more days and the weather almost always changes. The shooter that makes the fewest number of mistakes wins....

From there, the shooter compromises based on their budget, and shooting abilities.

So how much are you willing to give up?

Jerry
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My guess is proof of Jerry's comment would the fact that snipers kill bad guys at 2000 meters with 50 cals and not 338s....would that be a fair comparison???
 
Eager to learn new disciplines, all those event look so interresting, shooting never been a problem at my own pace, the pressure of those event must pump your adrenaline like crazy, will speak with Gary from Wantstall and will take arrangements to get a 260 barrel for the Nemesis, David Yves CEO of the Nemesis Arms Cie just talked to me, i will have to send my Nemesis back to California so they can headspace the new 260 barrel...JP.
 
dawgmaster said:
My guess is proof of Jerry's comment would the fact that snipers kill bad guys at 2000 meters with 50 cals and not 338s....would that be a fair comparison???
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The only reason they use such big boomers is because at 2km, bigger IS better.:rockOn:

I have yet to see a service BMG that will outshoot a bolt 338LM. The Barrett semi is rated as a 2 to 3 MOA rifle under ideal conditions. Not sure if the bolt BMG's are in wide enough useage to be considered standard service fare????

There is a difference between precision and anti-Material weapon.

However, all this will change very very soon as guided munitions get into service.

Then the 338 and pretty much everything else for LR "precision work" will cease to exist.

And it will be a 50cal world once again.

For F class, it is all about ballistics out to 1200yds with the vast majority 1000yds and in. Pick your poison and have at it.

There will always be compromises.....

Jerry
 
Mystic Precision said:
Doesn't the barrel install like a Savage? Get your paperwork in order BEFORE sending anything south of the line.

Jerry
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Gary will take the arrangements, it is easyer for dealer with the custom thing and all the tralala, i could loose it for a month or two, bof il take out the TRG or the Icon in the mean time.... JP.:p
 
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