Thread: Variables affecting precision

How I'd rate accuracy factors for hunting/long range shooting:

1) The Shooter.
2) The Rifle.
3) The Projectile (and if the rifle likes it).
4) The Powder (and how the projectile likes it).
5) The Charge Weight (accuracy starts falling off with velocity as you approach or exceed book max).
6) The Seating Depth (I just load to SAAMI specs and feel playing with depth is largely a waste and increases malfunction risks).
7) Esoteric stuff that can't be measured and I don't mess with it.

I have tried a lot of reloading methods, but now I basically do the Hornady protocol which I view as:

1) Get a good chronograph (Garmin Xero)
2) Pick a bullet and powder.
3) Start at low charge weight and go up a grain to 1/2 grain at a time towards book max to get my target velocity. Don't mess with tiny charge weight changes.
4) Try not to exceed book max as the added velocity often causes worse accuracy.
5) Shoot a 10 round group with target velocity load you want and see how it goes.
6) If the group is bad in first 5 shots, stop and change powder and/or projectile. Don't waste time messing with anything else. Bad groups never get better.
7) If the group is good, shoot it a bit more to get accurate dispersion/velocity numbers/zero.
8) Shoot at range to verify.

Doing the above I can have a load working or rejected quickly.

I have wasted a lot of time doing OCW, etc. and the above gets me the better results in a fraction of the time.

My notes on the Hornady method from their podcasts described above.

Choose your bullet.

Choose your powder.

Load in 1 gr increments initially. The higher you go, the more dispersion you get as velocity goes up.

Shoot for the velocity you want, but max velocity is less accurate the higher you go and more barrel
wear. Faster is not always best.

You’re going to need at least 20 rounds to know if a load is really worth keeping. ES and SD numbers
are not very useful until at least this sample size.

A five round group can’t tell you if a load is good (not enough data). However, a five round group can
tell you if the load is going to be bad.

Example: A 3MOA five round group is not going to improve. If you see this kind of group,
change bullet and/or powder for that barrel and try again. Don’t waste time messing with it.

If you don’t shoot large enough sample size, you may think you are improving your load making
changes but are just measuring the noise. Until you’ve shot at least 10 rounds you don’t know with 20
being better.

If a load is not shooting well, time to change your bullet or powder. Don't waste time messing with
seating depth, etc. Just do big changes and try again.

The more you know, The less you know!
True story

Sent from my SM-A556E using Tapatalk

Id love to understand the mechanics around why some powder and bullet combos shoot better than others. What is it actually doing that makes the bullet go skewif vs that other very similar powder that punches bugholes

Originally Posted by Nick-D

Id love to understand the mechanics around why some powder and bullet combos shoot better than others. What is it actually doing that makes the bullet go skewif vs that other very similar powder that punches bugholes

Greater or lesser variation in magnitude and direction of induced angular rate and cross velocity with variation in pressure-time function


sorry that's gibberish but there it is.


Also poor burnout (incomplete powder burn) causing blast-base interactions with unburnt powder particles.

Check out Jeff Seiwert's book "ammunition demystified" or read this - although it's pretty dense.


https://storage.googleapis.com/wzuku...nse%20Maps.pdf

Originally Posted by 19Badger

There are never any zero wind conditions, just those you can see and those you can't see.
In competition when the flags aren't moving I have seen people shoot BIG groups and think their gun/scope or something is broken, of course when the flags start moving and they shoot several good groups it shows they couldn't see what was making their bullets move all over the place.

If you aren't using some form of wind indicator when shooting all you are doing is guessing and being oblivious to something that affects the bullet, remember wind can blow bullets into a group as well as out.

The groups I was referring to were shot using a factory Sako in 223Rem, I have seen this rifle perform in competition more than once and the results were pretty similar both times.
I wouldn't have a clue how many different loads he tried before ending up with the final load but that load performs very well in that rifle, and he used the standard Benchrest tuning method of seating depth and powder charge to end up where he did.
I cannot take photos of those groups because the person that shot them has them, not me.

With a Benchrest rifle you can see the difference in seating depth and powder charge, and it is definitely more noticeable and repeatable than with the factory rifles I own and even more noticeable and repeatable at 200.
There are some who have joined the Benchrest group and bought Benchrest rifles because their custom rifles weren't as consistent as they thought they should be, I need to ask them if they find the Benchrest rifle is more consistent.

I can only comment about the rifles I shoot and what I have found.

gimp, perhaps you need to sit behind a Benchrest rifle and try it, experiencing the actual results will tell you more than listening to someone else, my offer is still open.

It seems like we more or less agree on the point that's relevant to this thread & load development discussions on the forum more generally - that whatever the effect size of tuning with charge weight and seating depth in a benchrest rifle (and I am yet to be convinced of that with evidence rather than hearsay but it's not the hill to die on here), it is not easily detectable in a hunting rifle, particularly a factory rifle - and people probably shouldn't worry about it very much


The reason BR keeps coming up of course is that people look at BR shooters "tuning" and assume that because those people do it, it must be necessary for good precision in a hunting rifle. My evidence so far just shows me that any effect that exists more or less cannot be resolved in the practical constraints of hunting weight shoulder fired rifles in the real world - even extremely high quality rifles with extremely high precision

Originally Posted by 19Badger

While the reloading equipment can matter the consistency of the process, to me, is the biggest contributor to accuracy.
A straight press and dies that create straight ammunition is the foundation, if your equipment makes "bent" ammunition consistent process won't fix it.

I have made competitive ammunition with mass produced sizing dies, Redding f/l bushing die and a Wilson seating die.
Most of the "Custom" reloading equipment is nice to have but it doesn't make any better ammo than a good press and good mass produced f/l die and straight line seater.
The best thing about a lot of the Custom reloading equipment is its smaller, lighter and easier to travel with.
There are many people who still throw powder charges and win, but it is the consistency of their powder measure and the way they use it that allows this to happen.
I am talking about 100, 200 & 300 Benchrest, which is where I have the experience and knowledge, mid range BR and Long range is different.

I, and all the Benchrest competitors I know, use the powder charge and seating depth to tune their load to the rifle/barrel, not everyone seems to know how to do that or what to look for.
Read the following books, Book of rifle accuracy - Tony Boyer, Extreme Rifle Accuracy - Mike Ratigan, Ultimate in Rifle Accuracy - Glenn Newick, The Accurate Rifle - Warren Page, Reloading Guide - Precision Shooting, Precision Reloading & Shooting handbook - Sinclair International, the first two are the most recent publications but they all have relevant information about accurate rifles and reloading.

I do not expect the same results and consistency with a factory rifle as I get with my Benchrest rifle and even custom rifles aren't as consistent as my Benchrest rifles.

I will also add that some of the processes that are required to make accurate ammo for my Benchrest rifle, don't seem to have the same result or aren't a noticeable improvement in a factory rifle.

While br rifles are clearly very accurate, and the low recoiling nature does help remove variables, the fact remains if you have poor resolution on your output data(small sample size), you can not identify efficacy of your input variables, in this case charge weight or seating depth.

The br rifles being very accurate doesnt negate statistics and rigourous testing.

Its pretty easy to test. Just shoot a couple of said charge ladders. If the results are consistent, well maybe you are correct.

Originally Posted by Nick-D

While br rifles are clearly very accurate, and the low recoiling nature does help remove variables, the fact remains if you have poor resolution on your output data(small sample size), you can not identify efficacy of your input variables, in this case charge weight or seating depth.

The br rifles being very accurate doesnt negate statistics and rigourous testing.

Its pretty easy to test. Just shoot a couple of said charge ladders. If the results are consistent, well maybe you are correct.

I wouldn't call a Benchrest rifle a low recoiling rifle, a 10 1/2lb BR rifle shot free recoil gets a run up to your shoulder and none of the rifles have recoil pads, lighten up the rifle even more and it gets pretty lively.

I have shot enough rounds through barrels attached to BR rifles and can tell you the aggregates at the end of 2 gun competitions, 20 x 5 shot groups give you a very good indication of what the accuracy of that rifle, barrel and load will do, I have put over 100 rounds through a barrel and still had an aggregate less than 0.400" for over 1000 rounds.

When tuning it is easy to see a group tighten up and grow larger by adjusting seating depth, all Benchrest competitors use this same method or a variation of it when they tune.
I would never try and shoot the loads Benchrest shooters use in Benchrest competition in a Factory rifle like a Sako 6PPC either.

I believe what I see and what I've experienced from multiple BR rifles and many barrels for each of those rifles, I've also taken barrels off one rifle and put them on another rifle and got the same results

Originally Posted by 19Badger

I wouldn't call a Benchrest rifle a low recoiling rifle, a 10 1/2lb BR rifle shot free recoil gets a run up to your shoulder and none of the rifles have recoil pads, lighten up the rifle even more and it gets pretty lively.

I have shot enough rounds through barrels attached to BR rifles and can tell you the aggregates at the end of 2 gun competitions, 20 x 5 shot groups give you a very good indication of what the accuracy of that rifle, barrel and load will do, I have put over 100 rounds through a barrel and still had an aggregate less than 0.400" for over 1000 rounds.

When tuning it is easy to see a group tighten up and grow larger by adjusting seating depth, all Benchrest competitors use this same method or a variation of it when they tune.
I would never try and shoot the loads Benchrest shooters use in Benchrest competition in a Factory rifle like a Sako 6PPC either.

I believe what I see and what I've experienced from multiple BR rifles and many barrels for each of those rifles, I've also taken barrels off one rifle and put them on another rifle and got the same results

I'm certainly not questioning that you or any other bench rest shooter can find and utilize an accurate load. Results are clear.

I do question the dogma though especially shooting small sample sizes. When developing a load with seating depth, what is the delta between the largest and tightest load?

My thesis is that those loads that shoot high scores would probably do so with a different jump, but would definately do so with a different charge weight.

Its worth mentioning I'm mostly referring to charge weights here.

Again though, regardless of the result the absolute fact remains, due to the random nature of shot placements inside the cone of fire, identifying "nodes" with small data sets of 3 or 5 shots is statistically very unlikely.

Can you actually make a 6PPC or 6BR benchrest rifle shoot poorly? What does that look like?

As simply as I can put it: Good results don't prove the process, demonstrably different results prove the process.

And only demonstrably different results within the functional window you'd actually use are relevant

Originally Posted by gimp

It seems like we more or less agree on the point that's relevant to this thread & load development discussions on the forum more generally - that whatever the effect size of tuning with charge weight and seating depth in a benchrest rifle (and I am yet to be convinced of that with evidence rather than hearsay but it's not the hill to die on here), it is not easily detectable in a hunting rifle, particularly a factory rifle - and people probably shouldn't worry about it very much


The reason BR keeps coming up of course is that people look at BR shooters "tuning" and assume that because those people do it, it must be necessary for good precision in a hunting rifle. My evidence so far just shows me that any effect that exists more or less cannot be resolved in the practical constraints of hunting weight shoulder fired rifles in the real world - even extremely high quality rifles with extremely high precision

Benchrest has shaped the firearm industry for many years, what has been learnt and has been successful in Benchrest has filtered down to your hunting rifle, the accuracy of hunting rifles now is far better than it used to be, in fact the accuracy of hunting rifles now would be the envy of many of the original Benchrest shooters from years ago.

From optics to Stocks, triggers, barrels, actions, all the improvements and development of these filtered into your factory hunting rifle. Fiberglass stocks were used in Benchrest for a number of years and were successful then eventually they appeared on hunting rifles.

Prior to buying a Benchrest rifle and competing in Benchrest I spent time trying to make my hunting rifle shoot like a Benchrest rifle. I was reading a magazine called Precision Shooting and it was primarily about Benchrest, Benchrest loading techniques and every other aspect of Benchrest shooting and equipment. It was quite an eye opener, they wrote about things I had never heard about before, I tried using those loading techniques to achieve Benchrest accuracy/consistency with my hunting rifle and it was very frustrating, one weekend it would shoot 1/2" groups the next with the same load they were just under an inch, then the following the groups would be just over a 1/2 inch again.

Once I purchased a good Benchrest rifle I learnt the difference between a Benchrest rifles accuracy/consistency and a hunting rifle, they were light years apart. It took a while to learn how to shoot and how to tune but now I know what the people writing in Precision Shooting magazine were sharing with the readers was actually true.

Mostly I agree with what you have put above, I think the biggest reason that the seating depth and powder charge tuning is harder to see or less noticeable with hunting rifles is due to the variability of the shooter, the variables of factory rifles, the variables of the rifle support, the additional recoil and the lack of wind indicators, I wouldn't say those are the only things but they are the things that I think contribute most.

It's easy to see the difference between the 3/4" groups and when the group shrinks to under 1/2" after changing your load, but you can also turn that 1/2" grouping load into a 1" group without changing anything in the load, just through how you hold the rifle or by not watching the windflags, but it is very hard to see the difference between the 3/4" group and the 5/8" group with a factory rifle.


I have to say after shooting Benchrest and seeing what it takes to shoot small groups and small aggs my expectations of my hunting rifle are a lot more realistic, and I don't expect my hunting rifle to shoot with the same accuracy and consistency as my PPC Benchrest rifle.
My view is that a hunting rifle that shoots 1" groups will cleanly take any game animal I want to shoot within the distances I hunt at, if I don't end up with a clean shot then it's my fault not the rifle.

I feel the biggest advantage of loading for a hunting rifle is to tune the rifle to the game you are hunting, ie suitable bullet and accuracy, saying all that a 1" rifle wouldn't cut it as a varmint rifle, ie shooting small targets at longer distances.

Personally, I don't think a lot of hunters spend enough time developing their shooting skills and many are the weak link in the system.

I can tell you what I've experienced over the years of shooting Benchrest and what I see regarding tuning, while I know what I write is the truth, it doesn't worry me if others choose to believe me or not, it won't change what I do or the results I see.

gimp, my offer is still open to you regarding the experience of shooting a Benchrest rifle.

Originally Posted by gimp

Can you actually make a 6PPC or 6BR benchrest rifle shoot poorly? What does that look like?

As simply as I can put it: Good results don't prove the process, demonstrably different results prove the process.

And only demonstrably different results within the functional window you'd actually use are relevant

Yes you can make a 6ppc shoot poorly, by 6ppc standards. It could look like a splatter where all 5 shots land in different places or you could have 3 in a dot and the other two 1/2" plus away in different directions
I can shoot 1/2"+ groups with a 6ppc and then change the load and seating depth and shoot groups under 1/4", I prefer to shoot the best loads in competition.
There are many people shooting Benchrest that can demonstrate the difference between a bad load and a good load.
A bad load is also affected more by the wind than a good load because the bullet isn't as stable.

You need a Benchrest rifle to experiment with, then you can share what you find.

Originally Posted by Nick-D

I'm certainly not questioning that you or any other bench rest shooter can find and utilize an accurate load. Results are clear.

I do question the dogma though especially shooting small sample sizes. When developing a load with seating depth, what is the delta between the largest and tightest load?

My thesis is that those loads that shoot high scores would probably do so with a different jump, but would definately do so with a different charge weight.

Its worth mentioning I'm mostly referring to charge weights here.

Again though, regardless of the result the absolute fact remains, due to the random nature of shot placements inside the cone of fire, identifying "nodes" with small data sets of 3 or 5 shots is statistically very unlikely.

I see you are from Tauranga, do you shoot at Tect Park?

For hunting weight and even competition rifles, doing things like trying to go from .75 MOA to 0.65 in terms of precision is often a waste. You can spend a lot of time and money on this very small change. Whereas if you just got a reasonable sub MOA load working and spent the rest of the time shooting at distance practicing wind calls and field shooting, you'd take precision from 3MOA field conditions to 2MOA or better. That is a much bigger change to making a hit.

Also at matches I have seen a lot of hyper-tuned loads cause malfunctions and DNF on stages for 0 points for shooters costing the match. High pressures blowing primers, long loads that don't feed, neck sized cases that don't chamber, sticking cases that jam up the bolt, and my favorite: long loads that get stuck in the lands when the operator opens the bolt. The bullet stays in and spills powder all over the chamber. People basically outsmarting themselves.

I suppose this is why I just work to get a load that shoots reasonably and reliably. Tuning is often a distraction from shooting time which moves the needle further.

Originally Posted by 19Badger

I see you are from Tauranga, do you shoot at Tect Park?

Yeah man