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ChrisWay

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Dec 18, 2018
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Shooter Inputs and Outputs



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The general theme of this article series is the effects of equipment and shooter on long-range pursuits. Understanding the equipment baseline is vital because it provides a starting point on top of which we must stack the shooter-induced elements we will touch on now. The reason we didn’t jump straight into the shooter effects on the bullet’s endpoint is that the shooter input always stacks on top of the equipment element. 



The Physics of It



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This isn’t a physics course, so I will try to generalize as much as possible here. Yet, a lot of shooting is basic applied physics, so it doesn’t hurt to bring up Newton in the...

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Great series. Between these articles, the straight dope and the recent Miles to Matches podcast discussing implementable training principles and ideas, there is some really good info out there! Keep it coming 👍
 
Has anybody run the real numbers and results of time bullet travels through barrel vs movements input by shooter?

Id like to see a pressure curve for chamber of a 18" vs a 26" barrel. I get the exit velocity is less with less pipe regardless, but to understand whats really going on behind the scenes I think that'd tell a story (is the relationship between pressure and acceleration linear or exponential?) Will a 12" barrel have 3x less [total bullet time in the tube] vs a 36" barrel, all else the same? Or is there more to it (I know theres more to it overall but specifically time in tube vs barrel length - I am not convinced its a completely linear relationship.

The motive behind all my seemingly stupid surface level talk goes back to simple fact that my first gun (20" Tikka 6.5cm CTR)consistently produced better PRS results UNDER 700yd than my newer ATX 6.5CM 24". In addition i was absolutely new to positional shooting with my first gun (CTR) so the results completely dont make sense on the surface.... ATX shoots groups wayyyy better - but its the positional stuff, the 'me' that effects something which ends up reducing my hit %. Maybe I just have a lucky rabbits foot hidden somewhere in my Tikka idfk.

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You can also apply the same general idea to tripod shooting. Seems there is a lot of misinterpreting of results with center of gravity way in front of, directly over or behind the center post of tripod (note: Im only really talking about clipping into tripod not bag off tripod).

Initially you think yea put it so its perfectly balanced
Then you say damn I wish I could get even more stable and repeatedly get those hits. If I clip behind CoG (towards buttstock) then a human wobble error of X will produced amplified wobble at muzzle because of fulcrum-magic. But for the same X shooter wobble error (say heartbeat even) with a gun clipped closer to muzzle (so CoG in front of tripod post) you'll get less wobble at muzzle (vis fulcrum-magic) with same exact wobble input from shooter to buttstock.

But after running some trials of this I found for me at least that there is another aspect that comes into play - weight/force/potential energy of the rifle itself. Essentially my answer has become clip in wherever but make sure to minimize weight behind the tripod center (within reason cmon); dump the weight forward of tripod center. And my reasoning on why IMO is there will be shooter induced wobble unless you free recoil the thing. So a wobble force of same X is pushed into the rifle through the buttstock so the more weight there, with the same initial 'push,' will translate into more force/momentum creating a larger inherent wobble zone at muzzle - and that [weight] factor supersedes the [fulcrum-magic] factor relating to mining your overall positional shooting wobble zone off clipped tripod. (using RRS TFCT34 tripod attached via ARCA).

PS another trick I like is to kick one of the tripod legs out further so the tripods footprint is no longer proportional all around (equilateral). The nonuniform footprint (isosceles) reduces the flex inherent in the tripod legs and results in less lateral shaking.

Just some things I've been thinking on lately.

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Love the direction of this series - things get unintuitive the smaller you go (quantum physics) so I say leave no stone unturned, just cuz your local best shooter does it 'this way' and obviously he's had success lets not overlook the minutia anymore....because the industry has already done its part on all the big stuff and the gear these days is amazing - but what new shooter even considers the possibility that how you manage the recoil (and trigger press/NPA) could effect the bullet trajectory as much as Kraft has shown us. I didn't.
 
Has anybody run the real numbers and results of time bullet travels through barrel vs movements input by shooter?

Id like to see a pressure curve for chamber of a 18" vs a 26" barrel. I get the exit velocity is less with less pipe regardless, but to understand whats really going on behind the scenes I think that'd tell a story (is the relationship between pressure and acceleration linear or exponential?) Will a 12" barrel have 3x less [total bullet time in the tube] vs a 36" barrel, all else the same? Or is there more to it (I know theres more to it overall but specifically time in tube vs barrel length - I am not convinced its a completely linear relationship.

The motive behind all my seemingly stupid surface level talk goes back to simple fact that my first gun (20" Tikka 6.5cm CTR)consistently produced better PRS results UNDER 700yd than my newer ATX 6.5CM 24". In addition i was absolutely new to positional shooting with my first gun (CTR) so the results completely dont make sense on the surface.... ATX shoots groups wayyyy better - but its the positional stuff, the 'me' that effects something which ends up reducing my hit %. Maybe I just have a lucky rabbits foot hidden somewhere in my Tikka idfk.

---------------------
You can also apply the same general idea to tripod shooting. Seems there is a lot of misinterpreting of results with center of gravity way in front of, directly over or behind the center post of tripod (note: Im only really talking about clipping into tripod not bag off tripod).

Initially you think yea put it so its perfectly balanced
Then you say damn I wish I could get even more stable and repeatedly get those hits. If I clip behind CoG (towards buttstock) then a human wobble error of X will produced amplified wobble at muzzle because of fulcrum-magic. But for the same X shooter wobble error (say heartbeat even) with a gun clipped closer to muzzle (so CoG in front of tripod post) you'll get less wobble at muzzle (vis fulcrum-magic) with same exact wobble input from shooter to buttstock.

But after running some trials of this I found for me at least that there is another aspect that comes into play - weight/force/potential energy of the rifle itself. Essentially my answer has become clip in wherever but make sure to minimize weight behind the tripod center (within reason cmon); dump the weight forward of tripod center. And my reasoning on why IMO is there will be shooter induced wobble unless you free recoil the thing. So a wobble force of same X is pushed into the rifle through the buttstock so the more weight there, with the same initial 'push,' will translate into more force/momentum creating a larger inherent wobble zone at muzzle - and that [weight] factor supersedes the [fulcrum-magic] factor relating to mining your overall positional shooting wobble zone off clipped tripod. (using RRS TFCT34 tripod attached via ARCA).

PS another trick I like is to kick one of the tripod legs out further so the tripods footprint is no longer proportional all around (equilateral). The nonuniform footprint (isosceles) reduces the flex inherent in the tripod legs and results in less lateral shaking.

Just some things I've been thinking on lately.

---------
Love the direction of this series - things get unintuitive the smaller you go (quantum physics) so I say leave no stone unturned, just cuz your local best shooter does it 'this way' and obviously he's had success lets not overlook the minutia anymore....because the industry has already done its part on all the big stuff and the gear these days is amazing - but what new shooter even considers the possibility that how you manage the recoil (and trigger press/NPA) could effect the bullet trajectory as much as Kraft has shown us. I didn't.
Love this, also another balance item I learned from @Diver160651 is if you clip in and have one tripod leg forward and 2 to the rear squared up, shorten the front leg slightly pushing the weight forward and still able to compensate with the anvil. This with cog, and or kicking the leg out achieve similar effects.
 
PS another trick I like is to kick one of the tripod legs out further so the tripods footprint is no longer proportional all around (equilateral). The nonuniform footprint (isosceles) reduces the flex inherent in the tripod legs and results in less lateral shaking.

Ok, this seems as if you have put a ton of thought into this. I am not going to say I believe you are right or wrong, just wrapped very tightly around the axel on something that isn't the same for every individual.

In my experience, shooting from tripods, hunting with them long enough ago that people ridiculed me, and then on to field matches several years later, I would say that much of the techniques are 90% gear dependent, a bit shooter physiology and the balance terrain dependent. With the better gear today, most of the techniques we deployed where no longer needed; except NPA and a solid square foundation still really payoff. You'd sell yourself short if you go so far down a rabbit hole you developed a single narrative on what works best, for only one situation.

Sometimes shooting a tripod all the way forward like a bipod, is the best solution, sometimes at the balance point and often as rear support. If you really want to see what your issues are, shoot a lightweight magnum standing & kneeling off a tripod on flat ground and try to see your impacts <400 yards, on 6" to 8" target; repeat on uneven terrain. This drill will teach you the balance between a stable solid NPA and wobble. Remember "if" your solution is to make your tripod base very large, you loose much of the flexibility on angled terrain, in rocks and in vegetation, and a bunch of other scenarios like increasing tripod height if needed to shoot over an obstruction.

Whatever trick you're using, it should be fast and easy to use the same concepts across a verity of terrain and applications or you'll start creating off-sets (POI shifts). Just food for thought..
 
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Has anybody run the real numbers and results of time bullet travels through barrel vs movements input by shooter?

Interesting research. I did some research regarding bullet time in barrel from sear break to barrel exit pertaining to shooter follow-through. But nothing pertaining to tripod wobble or unstable shooting platform. FWIW, Attached is file.
 

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Love this, also another balance item I learned from @Diver160651 is if you clip in and have one tripod leg forward and 2 to the rear squared up, shorten the front leg slightly pushing the weight forward and still able to compensate with the anvil. This with cog, and or kicking the leg out achieve similar effects.
That's been a technique I use on my tripod all the time now - make the front leg about 2-3" shorter than the rear two legs. As @Diver160651 put it in his now near-legendary "Tips & Tricks" post, doing this shifts the center of gravity forward of the center of the tripod , so recoil doesn't transfer to the tripod the same way, and the tripod naturally wants to stay in it's resting position rather than the whole assembly wanting to rock backwards with recoil.
 
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My overall message was really simply to say [there is more fruit on the tree] lets get it - maybe the low hanging fruit is all gone by now (i.e. free float the barrel) but there are more areas (IMO) both large (always/rule of thumbs) and small scope (only if) insights that are worth looking into for grounding the strategy (makes sense/why it'd work) as well as learning/applying it and seeing results.

The tripod part was just an aside with small use case, but it portrays a larger issue in gun community (IMO) that Hectorrr won a lot, Hector employs his tactics like [this], so therefore the best way to accomplish xyz is to do what Hector says to do. Or perhaps how to get same results as Hector with cheaper/less gear. But Hector does have a lot of hardware.

Y'all are right though, (could be less of a [universal truth(s)] type search and more of a [personal preference/what works best for me] thing....."more than 1 way to skin a cat..."

etc etc etc so maybe Im just figuring out my version and typing on the Hide about it along the way lol?
 
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