OzFclass

Barry Davies wrote:Alan,
Maybe, theoretically, but the question was with respect to " handling " not rifle weight.
Barry

The weight vs the 'handling' are one in the same thing. The common denominator for me is the systems "inertia value" and leaning into a rifle raises its inertia value

Plumbs I will get back to you. Thanks for your input.

With regards to recoil if the mass at the fulcrum point differs then the barrel lift differs. This can explain why zeros are different for people using the same gear. I suggest an experiment would be to put the butt of the rifle against a tree or fence post, fire and measure the velocity. Next suspend the rifle on lines so there is a greater degree of freedom, fire and measure the velocity. Is there a speed difference?

We are getting off topic , but plenty of my own testing during Development squad seemed to susggest keeping the same position especially with the shooters elbow . Even with a mag speed I’ve seen some differences . I’ve heard of larger massed shooters getting another 20 fps out of the same rifles with a different shooter .

The above is the main reason I changed from the Marine’s type position ie straight in line with the stock ,to more of an angled to the left position. Some how it settled down recoil and had very consistent velocities.
All I can say is test it your self and see if u get the same result ?
Not much worth on a 6 br but a 7 saum or 308 , something that does recoil.

By my rough calculations, the effect on muzzle velocity of rifle weight and of shouldering vs free recoil, is much less than some are saying. This stems from the fact that a typical F-Class rifle is about 800 to 1000 times the mass of a typical projectile. The conservation of momentum principle dictates that if a projectile of 10 grams (155gn)has a muzzle velocity of 3000 ft/sec, then a completely unimpeded rifle of 7Kg will incur a rearward velocity of about 4 ft/sec. I believe that is the maximum increase in muzzle velocity that would be achievable by increasing that rifle's weight or by putting the butt against a fixed object. In practice it would be less.

Much less Alan as even with shouldering there is backward movement -- a shoulder is not a fixed object ( like a tree ) but even then it's only a relative increase, not an actual increase, certainly nothing a chronograph not attached to the rifle would register.
Barry

Alan,

I was going to post almost exactly what you said on change in MV due to rifle weight.
I also think that the free recoil distance of only a few mm for a heavy rifle is such that the rifle is initially recoiling against air or loose clothing or a spongy recoil pad and the bullet has left the barrel long before any serious forces impede the rearward motion of the stock.

I doubt that most Chronies have the resolution to accurately resolve variation in V. Also the natural spread of V from loading would mask it.

Even a LabRadar may have trouble.

If someone wants to test this properly they would need to fire about 20 shots alternating between free recoil and butt against a solid object.
This would help to isolate effects like barrel temperature.

Even then, recoil in the real world against a less than rigid object would reduce the effect in practice.

It is often far harder to 'prove' a theory 'Scientifically' than one thinks. The results need to be repeatable every time it is tried or it 'aint science'.

Peter Smith.

'Tis what it is lads !! Hence I suggest we be using the chrony.

Now I see mention of this chrony vs that chronys accuracy. So which chrony are we going to use and perhaps we need to be using the right chrony at ALL times ?

Plumbs says we be getting off topic. I think not.

Just had this image of guys looking for stumps. What is important here is the fulcrum point to keep on topic and the impact on barrel lift in relation to the bore line which effects the fundamental vibration. Position and movement out of position is very important here. Even moving your feet and legs. Torque can upset bag handling but not so much the actual shot velocity. But hopefully I demonstrated before its the speed of the vibrations that is more important than bullet speed for group size and that is connected to the fundamental vibration of lift.

williada wrote:
So if we think about it, the speed of the bullet less important than the speed of the vibrations. Point two of a grain of powder extra, won't change bullet speed much, but it has a big impact on vibration speed as do small tuner movements.

The above quote is exact reasoning why i dont take any notice to muzzle velocity..

Williada,

When I looked at your diagrams of groups above, I was very surprised what effect the tuner had made to those groups, more so now knowing how small the adjustments were...
There is no way at 140y with a naked barrel I would get "coning" characteristics like that... If i was to do .2 increments over 6 loads/tests working up to my accuracy load not one of those groups would measure over .250"...(3 shots) Regardless of barrel profile...


My thoughts were when I seen them....WOW and ive now got to ask...
Was the load used in those diagrams the most accurate tested load before tuner adjustments?
Are those "coning" characteristics normal when using a tuner?
Was those "coning" characteristics apparent before tuner was adjusted when working up a load?
This is only an assumption from diagrams but is it possible there is a fitting error or is it possible tuner has a balance issue? (heavier one side)..

Just my thoughts

Cheers
Alan

Yes, Alan the load was the most accurate load tested before the tuner was used. The gear was smithed correctly. I think Matt P fitted the barrel.

n.b. Not any old tuner can produce those characteristics. In fact the wrong tuner match can destruct vibrations we need because each barrel has its own personality. Tuners are ideally constructed to match barrel personality, then the patterns can be enhanced and are repeatable. Then people have to be trained to recognise patterns and make the appropriate tuner adjustment forward or back in differing amounts of adjustment depending conditions and distance.

That load was to demonstrate appropriate tunes with stable velocity to demonstrate what tune does to group shape. It is ideal for the beginner to use to set and forget like a barrel without a tuner.

To the trained eye those characteristics were apparent during a special load development process at the 140 yard distance when the projectile is least affected by coning which has been used by a few Queens winners which I have done private analysis for to find the best tune position without a tuner.

So if it is not broke, don’t fix it if you do not know what you are doing. Unfortunately that takes time and ammo to learn. There are lots of patterns in group dispersion to get your head around for analysis where learning only comes with experience like any trade if you do not get a mentor to show you where to look. Unfortunately, the competitive nature of the sport means thinking becomes tribal. I would like to see the most skilled marksman win who can judge wind and light and not pretend to be the best marksman because technology has assisted them.

No, the tuner does not have a fitting error. These results are common for those in the know. In the case of a TR Australian Team member a few years back who asked for help when his issued barrel would not perform. The week before he left the country, I showed him how to use a fitted tuner in person over different ranges. He won the Nth American Long Range Championship then went on to win the NZ Queens in TR. The right tuner gives killer accuracy. David.

David,

Thanks for the information above much appreciated. My thought process has now changed in regards to your diagrams, knowing a few more details.
I would be assuming the rifle was sitting in a V Block?
Your tribal comment is too true .

Cheers

Alan

I’m sorry for leading everyone astray with hard shouldering or free recoil, Alan’s Math says it plain and clear . But my experiences at times says otherwise .
Oh my gosh ! This sport is off the chart as far as for thinking stuff over !!
All of the newbies I think are about to jump off the end of their lounges in shear dismay lol!

I think there will always be experience versus science . There are a lot of top shots in the sport that have the nack of super tuning a rifle and I’ve seen one do it with a few shots jumping the rounds 140 thou , and doing that on the firing line with a hand bullet seater ! ( MF )
But Ask these people “ how do u do it “ , I’m not sure if they can explain!!

I’ve myself have done a poor attempt in experience language, but I’ll keep trying . Williadia I think is our Bryan Litz and some of the success we have enjoyed has come a little bit from his teaching! Well for me anyways

Thanks David for another couple of very interesting posts, just love reading them and getting my head around them. Thank you for sharing just a little of what you know.

Cheers
Danny

David, if you still have my email address ,please contact me.

Cheers
Danny Sandford

GSells wrote:I’m sorry for leading everyone astray with hard shouldering or free recoil, Alan’s Math says it plain and clear . But my experiences at times says otherwise .
Oh my gosh ! This sport is off the chart as far as for thinking stuff over !!
All of the newbies I think are about to jump off the end of their lounges in shear dismay lol!

I think there will always be experience versus science . There are a lot of top shots in the sport that have the nack of super tuning a rifle and I’ve seen one do it with a few shots jumping the rounds 140 thou , and doing that on the firing line with a hand bullet seater ! ( MF )
But Ask these people “ how do u do it “ , I’m not sure if they can explain!!

I’ve myself have done a poor attempt in experience language, but I’ll keep trying . Williadia I think is our Bryan Litz and some of the success we have enjoyed has come a little bit from his teaching! Well for me anyways

U have not lead any thinking person astray Graham with your own experience about MV's !!

Bryan Litz is SORELY needed here because he's a clever bastard ( pardon my language Bryan ) who understands the rules of the game very well. It has been said he has 'interests' though. That is just nonsense ! Science used properly has NOTHING to do with interests.

Bryan Litz could PEER REVIEW the theory/s being put forward here. I used those two words earlier in this thread and got a most curious version of what it means : "circular reasoning" is I believe what that version is known as.

Science helps us to understand many things better. To just say something is 'proven' is a completely different story !