If ballistics is a science ....

Get or give advice on equipment, reloading and other technical issues.

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Handbrake
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If ballistics is a science ....

#1 Postby Handbrake » Wed Mar 06, 2019 8:01 pm

If ballistics is a science why is it so difficult to get consensus on issues relating to reloading?
I am a relative newbie to F Open using 6.5x47 Lapua and having bought another box of new cases checked the neck thickness which ranged from .0125 to .013. I have tried to get clear advice on whether neck turning is necessary prior to first loading, after first loading, when the differences gets to a certain percentage, not to bother as there will be minimal benefit, etc., etc.,
From what I have been able to understand so far in broad terms consistent tension and thus release is a critical component to good loads. Any thoughts?

macguru
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Re: If ballistics is a science ....

#2 Postby macguru » Wed Mar 06, 2019 9:12 pm

Only simple scenarios can be explained 'precisely' by mathematical models. I say precisely in quotes because you are assuming the formula is right but all formulas are models. In physics a system of 2 bodies orbiting each other can be predicted pathwise but if you look at the solar system there are too many variables to give "exact" solutions although we do pretty well anyways. In the real world everything impinges on everything all the way to infinity...
With reloading, there are lots of variables interacting with complicated harmonics and the best we can do is vary one thing at a time and see what happens.
Variables: calibre,powder,powdercharge,primer,bulletweight,bulletshape,riflingpattern,twistrate,barrellength,barreltaper,barrelweight,casecapacity,temperature,airdensity,range etc etc
I am sure thats only about half of them :) Its a wonder we can hit the x ring at all !

wsftr
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Re: If ballistics is a science ....

#3 Postby wsftr » Thu Mar 07, 2019 4:09 am

Define necessary. I've got plenty of 1k targets that show .5moa or less without neck turning. I don't however hold any 1k BR records.
Yes consistent neck tension plays a part - the question for turned vs unturned brass - when will it start to show a difference. IME using Lapua brass its somewhere below .4 -.5moa at 1k.

bruce moulds
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Re: If ballistics is a science ....

#4 Postby bruce moulds » Thu Mar 07, 2019 6:18 am

the main science is how to establish what really works.
this as opposed to setting a criteria of what "should" work and working towards that.
since the advent of 6br website we have seen much more of the latter, particularly chasing specific velocities in the hope of accuracy.
and basing conclusions on one barrel only.
some now also do not include the amount of air and light between the muzzle and a long range target making specific results hard to repeat.
this is a game of statistics, and as such is not definitive.
bruce.
"SUCH IS LIFE" Edward Kelly 11 nov 1880
http://youtu.be/YRaRCCZjdTM

superx10
Posts: 56
Joined: Wed Aug 19, 2015 9:32 am

Re: If ballistics is a science ....

#5 Postby superx10 » Thu Mar 07, 2019 9:26 am

I have found the 6.5*47 to be an incredibly easy cartridge to shoot accurately or to make it shoot small groups it is then up to the fclass shooter to steer it to the center of the target, I would also only neck turn if the reamer used was a tight neck otherwise aim for a small amount of neck tension on the bullet say .020 about two thou, one of the biggest advantages of coating bullets ie HBN is the release of the bullet I also do this.

If your measuring and not using high-quality Japanese made instruments like Mitutoyo and do not know how to get repeatable performance then who really knows what the true measurement is.

A physicist with an honors degree is no more likely to win a big fclass event than a tradie so don't get caught up in "the paralist of the anylist " with the 6.5*47 just load and shoot, don't try and push this little cutie to hard its not made for it, huge accuracy window from 1900 to about.22750.....fps with 140gr 2208 or 2209.

The biggest investment you can make to improve your performance is in motel rooms and petrol.
SM

superx10
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Re: If ballistics is a science ....

#6 Postby superx10 » Thu Mar 07, 2019 9:28 am

22750 FPS may be out of reach, but 2750 should be.

williada
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Re: If ballistics is a science ....

#7 Postby williada » Thu Mar 07, 2019 1:16 pm

Anneal cases, volume sort, expand neck, skim turn, full length resize and watch for carbon pattern on the neck to determine desirable neck clearance for acceptable gas seal on firing. All IMO of course. Good sense is like good science, we all learn from our mistakes. Big difference between good sense and common sense.

macguru
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Joined: Wed Aug 05, 2009 9:49 am

Re: If ballistics is a science ....

#8 Postby macguru » Thu Mar 07, 2019 7:17 pm

I think that once you get an F class rifle that can shoot an x ring sized group (or better, 1/2 x ring sized) then the biggest gains come from wind reading and thats more an art than a science. There are plenty of f class shooters that can get 60.5 - 60.10 in a dead calm because the gear we have is so good now....

The word 'science' is often misused by non-scientists .... All models are approximations and at one end there is pure science (theoretical physics) and at the other end is technology ( engineering design, metallurgy, and yes reloading) The technologies involve trial and error and COMPLEX systems so there is no simple 'formula' for success. A scientist could probably not improve on a samurai sword although they can 'explain' why they are so good... Its just as well that so many different combinations of calibre and components can get that sub x ring group....

bruce moulds
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Re: If ballistics is a science ....

#9 Postby bruce moulds » Thu Mar 07, 2019 7:43 pm

macguru,
it is good to see that 1/2 xring vert is achievable on call when you get ammo and rifle right.
such inspiration is what keeps me trying.
bruce.
"SUCH IS LIFE" Edward Kelly 11 nov 1880

http://youtu.be/YRaRCCZjdTM

Tim L
Posts: 418
Joined: Mon May 19, 2014 7:11 pm
Location: Townsville

Re: If ballistics is a science ....

#10 Postby Tim L » Thu Mar 07, 2019 8:09 pm

The example you use is a great example of why there is little concensus. You talk of neck "tension" but we measure it in length. We aren't measuring tension are we? We are assuming the tension achieved by measuring the increase in diameter of the brass, not even the circumference but the diameter, so we are down to 1/3rd resolution already. We "assume" the elasticity of the brass, we "assume" it is consistant if the neck wall is consistant.
Science? No. Its not even half good engineering.

macguru
Posts: 1314
Joined: Wed Aug 05, 2009 9:49 am

Re: If ballistics is a science ....

#11 Postby macguru » Thu Mar 07, 2019 8:24 pm

Bruce, in North Sydney, and at F class comps in NSW I see 1/2 x ring groups quite a bit. Maybe not all 10 shots, but most of them. I can think of lots of shooters who can do this, especially on the first shoot of the day, shooting a rifle chambered by one of our top gunsmiths.

RJNEILSEN
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Location: Brisbane
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Re: If ballistics is a science ....

#12 Postby RJNEILSEN » Thu Mar 07, 2019 9:05 pm

I expect if you could clone your rounds a couple of hundred times and have them shot in cloned barrels by cloned shooters, then the science would be more obvious. Unfortunately none of us have the time to list the hundreds of variables in a single post that affect what happens to projectile flight from trigger squeeze to impact. I am far from an expert however I do appreciate the variables and now attempt to focus on what is important in order of - magnitude of affect (time permitting).

Ryan.

bruce moulds
Posts: 2530
Joined: Sun Jun 19, 2005 4:07 pm

Re: If ballistics is a science ....

#13 Postby bruce moulds » Fri Mar 08, 2019 7:03 am

macguru,
your first statement is what we aspire to.
your second is more a definition of reality.
bruce.
"SUCH IS LIFE" Edward Kelly 11 nov 1880

http://youtu.be/YRaRCCZjdTM

Barry Davies
Posts: 1228
Joined: Tue Aug 24, 2010 12:11 pm

Re: If ballistics is a science ....

#14 Postby Barry Davies » Fri Mar 08, 2019 7:17 am

And therein lies the difference between what we do and what others do. We are worlds apart --to each his/her own.

Gyro
Posts: 413
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Location: New Zealand

Re: If ballistics is a science ....

#15 Postby Gyro » Fri Mar 08, 2019 1:05 pm

Realise too the Top shooters have been around long enough to have a pretty good handle on what matters and what doesnt. Obviously they are the ones who are best to take advice off !!!

Im not sure how much experience the questioner has .... but even if somebody wrote down all the answers and gave them to you, then the shooter would still need to do a LOT of hard yards to become a top shooter.

Theres a hell of a lot of technical stuff to understand in the F Class discipline.

I reckon lots of F shooters have rifles capable of very accurate shooting. BUT lots of 'problems' prevent that happening on a consistent basis.


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