6.5 PRC Ballistics - drops don’t match ballistics chart

[Capt RB]

One other thing to check is your parallax. Did you adjust for each distance? This can have an effect on impact from minor to profound

 

[Canadian Bushman]

Shoot all groups from the same position, on the same day, at the same target, with the same data, and the same lot of shells.

You are trying to measure one variable as closely as possibly. Dont throw any more into the mix.

 

[Holycity73]

Real quick...
POI can shift due to anything from ammo and brass to temperature and support system. Testing should always be done in a controlled environment using the same shooting position, support system and if possible, atmosphere(Indoor for example).
trusting load data from a manufacture is a nice place to start. The real data comes from load development to the specific rifle only. Load data must be proven true. The ONLY way to do so is through shooting at known distance.
Everyone wants to pretend that their numbers are set in stone once a rifle is dialed. This is far from true.
You POI is subject to the world around it once it leaves the barrel.
Using a tripod for testing shows poor fundamentals in regard to a baseline, that's all. Adding more variables for failure proves that. Bench or prone with good support fore and aft for load data are best.
Now as for real world applications once development has concluded, I encourage everyone to shoot as many positions with as many support systems as possible. It makes you a better shooter AND prepares you for the INEVITABLE POI SHIFT.
I would never attest to a shooters fundamentals, or lack there of, without spending range time together. what I can easily attest to is the frustration of the forums telling you what you're doing wrong and even more rarely, right.

Go shoot your rifle as much as possible. Get a good shooting partner. Go out and kill stuff.

ps, I run a 6.5PRC with stellar results. Did no one ask how many rounds the op has through his barrel? Mine sped up significantly around 90 rounds... and the POI shifted

 

[Holycity73]

.

 

[X47guy]

Stop typing this in this forum. You are flat WRONG. POI will shift depending on a number of things outside of your personal form or fundamentals PERIOD.

If you have a solid zero from a bench and then drop prone, your POI should not change.

I guess guys like Jake Vibbert, Dave Preston, Matt Brosseau, and several other shooters check zero before every single stage and position.

 

[FURMAN]

If you have a solid zero from a bench and then drop prone, your POI should not change.

I guess guys like Jake Vibbert, Dave Preston, Matt Brosseau, and several other shooters check zero before every single stage and position.

I would say 50% of the time you zero a rifle on the bench it needs re zeroed from prone. It is even more important with heavy recoiling rifles. We are not taking about 15 lb dashers here. Give up you are wrong. Let us just pretend you were correct I would not be able to take my rifle out every single time after I have zeroed with my rear rest and bipod and drill the center of my targets if my form sucked.

Also are those guys shooting .25moa groups? No they are hitting steal plates. You are clueless if you don't believe their rifles would have different group POI from those odd positions. Believe what you want your ideas are incorrect and will NOT help the OP solve his problem.


Every single person I personally know who can repeatedly hit the center of a target long range form field positions with a typical long range hunting cartridge in a long range hunting rifle zeros from prone with the equipment they will be using. Once again if their poor form was the issue they would not be hitting targets. Many topics on this forum are debatably and varying opinions are good but this one is just a fact. Different shooting position=different poi. We zero for the shooting position we plan to use most.

 

[Canadian Bushman]

If you have a solid zero from a bench and then drop prone, your POI should not change.

I guess guys like Jake Vibbert, Dave Preston, Matt Brosseau, and several other shooters check zero before every single stage and position.

Why do you suppose prs shooters have been using smaller calibers/bullets each year?

 

[Killertraylor]

A lot of advice here, some good, some awful. My only input would be to switch optics. Some Leupold VX-6's have had issues holding zero and tracking correctly at distance. If you have a Kahles, March, Nightforce or Swarovski, plop it on there and run your test again. Good luck on your hunt!

 

[X47guy]

Why do you suppose prs shooters have been using smaller calibers/bullets each year?

so why can Jim See, Kevin Shepherd, Buck Holly continue to do it? We shoot smaller cartridges for the recoil management and spotting. It's a lot easier to manage recoil on a 6 BR than it is a 6.5x47L. Weight will hide fundamentals also. The bottom line is our POI doesn't change when we change position. If our POI changes, it is something we missed whether be on the reloading bench, environmental or fundamentals.

 

[FURMAN]

so why can Jim See, Kevin Shepherd, Buck Holly continue to do it? We shoot smaller cartridges for the recoil management and spotting. It's a lot easier to manage recoil on a 6 BR than it is a 6.5x47L. Weight will hide fundamentals also. The bottom line is our POI doesn't change when we change position. If our POI changes, it is something we missed whether be on the reloading bench, environmental or fundamentals.

You are GODS amongst mere mortals. For the rest of us we will have to check our zeros from prone if we developed our loads on a bench.

 

[FURMAN]

I am sure Aaron does not know how to shoot...

 

[Canadian Bushman]

I apologize to the OP for de-railing his thread.

I will finish this discussion in a PM.

 

[WiscGunner]

so why can Jim See, Kevin Shepherd, Buck Holly continue to do it? We shoot smaller cartridges for the recoil management and spotting. It's a lot easier to manage recoil on a 6 BR than it is a 6.5x47L. Weight will hide fundamentals also. The bottom line is our POI doesn't change when we change position. If our POI changes, it is something we missed whether be on the reloading bench, environmental or fundamentals.

zero changes as well as velocity changes from different positions. Cheek position, eye box and length of pull change in different positions. These are "facts" because of the thousands of variables at play. The POA of the rifle does mot change but reverb from a bench if different than reverb from a bipod in sand which is different than a bipod on concrete which if different.... The recoil impulse (thus velocity) is different standing vs sitting, vs prone vs shooting with your back in a tree. There simply are too many points where the physics involved change for anyone to say a rifle zero'd is a rifle zero'd. Our goal as a shooter is to compensate for these changes and shoot differently from each position so that each position behaves the same. To think otherwise is foolish ignorance. This is why shooters in PRS are moving to light recoiling rifles, heavier systems and poorer fundamentals...simply reduces the variable to free recoil the rifle. Hiding the physics involved with bigger targets or lighter recoil doesn't change the fact that they are there. This is easily tested and most people do to some extent so that we can adjust for the results.

now if you are free recoiling off a bench with slick bags and free recoiling in pro e off the same bags then the position of the rifle hasn't changed, the relationship of the shooter hasn't changed, and the relationship to the support surface hasn't changed so the POI won't change. This however is not practical in a stretch of the term.

Perhaps you could try not to be so argumentative and try to answer the OP's question with helpful science and not just some vague buzzword like "fundamentals" as if saying the word implies you have mastered all its vast encompassing knowledge.

There has been great suggesting addressing the dozens of holes in the OP question due to lack of information. Sadly, we all need more details from the shooter to provide relevant information to help. As it stands we are all just guessing at the infinite possibilities without more detail.

 

[Ingwe]

If you think about all the variables involved, sometimes it's a wonder that we hit our animal...even though our POI changes with different shooting positions, thankfully it's obviously not enough to matter THAT MUCH and that's what we need to keep in mind, have fun, and not obsess so much.

I obsessed for a long time about this but I finally figured out what my biggest shooting flaw is....changing cheek pressure. I will shoot 2 or 3 clover leafs then but the next one 1/2" low and to the right (I'm lefty)
If I shoot enough at one target, oftentimes I can see 2 different groups.

try to figure out what's going on and go from there