Gyro wrote:....if you release shots at a target with the rifle not on its NPOA ....
NPOA = natural point of aim?
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Gyro wrote:....if you release shots at a target with the rifle not on its NPOA ....
Gyro wrote:wsftr wrote:this is well worth a read. In particular the conclusion.
https://blog.ammolytics.com/2018-12-12/ ... ocity.html
I found it fascinating that he measured a forward motion before recoil that he attributed to the firing pin.
Conclusions
When shooting a precision rifle, preloading your bipod is an incredibly effective technique for managing recoil and getting your sights back on target to watch for impact or prepare for your next shot. However, if you expect it to have an effect on your muzzle velocity, you're going to be disappointed.
Here's what I learned and observed based on the experiment I described above:
I measured no change in muzzle velocity with either technique.
Due to huge differences in mass, the bullet has left the barrel before the rifle moves under recoil.
Chamber pressure readings verified that some of the rounds shot with a preloaded bipod were slower by coincidence, not correlated to or caused by recoil technique.
The median velocity is more robust than the mean (average) and is better suited for ballistic calculators.
My reloading practices need improvement, likely around bullet sorting.
The real problem for me here that's not mentioned in the conclusion is that as many of us know : if you release shots at a target with the rifle not on its NPOA then the bullets will go everywhere. This is a fundamental to accurate shooting and plays out in all kinds of ways across all shooting classes. For an F Class rifle, of either class, the guns relatively higher inertia value compared to say a carry-around sporting rifle may perhaps lessen this dynamic, but believe me if you handle an F Class gun incorrectly/inconsistently you will not shoot well. And I suggest if you are shooting a cartridge/bullet combo that generates a relatively higher "gun upset" during recoil then the problem just get worse.
Whether the velocity is affected or not I have no idea ( despite many saying it is ) but I would presume it would be, just from basic physics theory.
AlanF wrote:Gyro wrote:....if you release shots at a target with the rifle not on its NPOA ....
NPOA = natural point of aim?
bruce moulds wrote:gyro,
you need to start from a foundation, or all else is wasted.
as an aside, congrats on doing a successful lapping.
my experiences doing this with bullet moulds have not always been happy ones in terms of roundness.
bruce.
Handbrake wrote: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?
John T wrote:Hello Handbrake.
Did you earn that name at your golf club?
Can I suggest that at this early stage of your F Open career, you keep to the basics and take developments slowly. Neck turning is an acquired skill. There is much more to it than ripping a few thou off a case neck. Ruining 1 in 3, $2.50 cases is expensive education.
Only an experienced neck-turner could improve on cases which have only 0.0005 variation. So, forget about neck turning, for now.
Your loaded necks should measure 0.289 to 0.290.
Your chamber neck should be no more than 0.293.
I guess that you have a Full Length resizing die with the standard de-capping rod with an expander ball. That assembly is not likely to deliver necks which are in-line, a serious no-no.
Buy a bushing die, a 0.286 bush and an "expander" from Barry Davies that will give you your desired neck tension, say, 0.262/0.002.
Regards,
John T.
10.3.19
Handbrake wrote: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?
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