I'd marry Audette herself if she is the one who came up with the method of load development. I have a feeling that she would be a little old for me so I'll take her daughter if it's possible!

This method is the only way to go.


I've been using 43.0 gr W-760 with the 139 gr Lapua Scenar in my 6.5 Creedmoor. I picked the charge from a previous ladder, loaded it and shot it at 100 and it gave .4" groups. It stayed 1/2 MOA out to 700yards. Velocity is a little anemic, so I shot another Audette yesterday to try to find another node.






Shots 3,4,5 clustered and were at 43.4, 43.6, and 43.8 grains. I bumped my load to 43.6gr and went out this morning.........






Shot that rediculous group in a 15mph crosswind from 10 O'clock...3 shots that are right at 1/2"!


The load instilled confidence all the way out to 760 yards with no vertical dispersion.


Also ran into him....

Hey your friend is kinda cute! What species is he?
Where were you two?

muck

Albuquerque.

Just re-read my post. I guess that group doesn't seem rediculous until I tell you that it was shot at 300 yards!

Hey rc

Looks like a Painted Desert Glossy Snake about to molt

I think you're right woods.

Are you a reptile buff?
I never cared about them enough to search for the species.

Nope, no expert or big fan. Don't kill them unless they are poisonous in a populated area though.

Hey rc, I never did prove anything to myself with the Audette other than it is a fact that the faster you push a bullet, the higher the POI gets on the target.

For example here is one


now you might say 5, 6 & 7 looks like an accuracy node or you might say 1, 2 & 3 look like one. But in reality I just picked a load that gave me the velocity I wanted, shot a 5 shot group just below it, a 5 shot group at that load and a 5 shot group just above it to check for general accuracy. Then adjusted the seating depth out till I got what I wanted. Ended up with a load close to #9 on my target.

Shoots great!

Audette is sorta like OCW (HC is gonna love that statement ), like reading tea leaves and you can read more into it than you should and get different results if you do it again.

Looks like you have a great rifle and I'll bet you could make it shoot just as good at any powder charge weight you chose.

BTW, I think someone saw Audette's daughter around the neighborhood lately

I'm with ya woods on the only killing the poisoness snakes. I just played with that one until he got riled up and acted like this one....






This guy had no rattles. He just coiled up, raised up high and hissed. My Labs and I found him on my gun club's archery range. Mamma dog had a close call with him. I rounded up the dogs, got them in the truck and headed back with a camera and a shotgun.........




Woods!!!!

You're really starting to shock, amaze and scare me!!

quote:

now you might say 5, 6 & 7 looks like an accuracy node or you might say 1, 2 & 3 look like one. But in reality I just picked a load that gave me the velocity I wanted, shot a 5 shot group just below it, a 5 shot group at that load and a 5 shot group just above it to check for general accuracy. Then adjusted the seating depth out till I got what I wanted. Ended up with a load close to #9 on my target.

This sounds a tad like my old, de-bunked theory about choosing a safe max load (the velocity you want) and doing the tuning with seating depth! What's up?! I'd hide behind the couch from HC after that one too!

Since our conversations about the "Tuning any load to be accurate with just seating depth" theory, or "Which has more bearing on accuracy, Seating Depth or Charge Weight" question, I've thought I've found the answer for sure with the Creighton-Audette method. It has worked beautifully for me. There have been some frustrations for sure like with my .264 Win Mag. I've shot ladders with 4 different bullets, picked nodes, loaded them and none have panned out. But I don't think it's the method. I think I've got a barrel problem and it's back to the gunsmith's.

I think you're generally following Audette's method by picking loads around the node, trying them, choosing the most accurate then tuning with depth. But boy you sure came close to endorsing that seating depth theory



I would still consider Audette's daughter just to learn more about this thing that keeps us around here and the range.........everybody's has to make some sacrifices and take one for the team!

Also,
jeffeoso will argue about the higher velocity shots impacting higher theory.............

God but i hate snakes!

All that stuff about them avoiding you is nonesence. In Belize the camp cooks were forever leaving uneaten food and the waste bins unsealed. This would attract the rats who in turn attracted the snakes. Nowhere was safe from them.

It was worse in the jungle as they would seek you out in the darkness. Never gave them a second thought until posted to Belize - i'll walk a mile out of my way to avoid a snake.

Hey rc

I don't think Audette is totally useless, after all any trigger time has some value. But let's just look at your posts so far

quote:

I've been using 43.0 gr W-760 with the 139 gr Lapua Scenar in my 6.5 Creedmoor. I picked the charge from a previous ladder, loaded it and shot it at 100 and it gave .4" groups

So you had an excellent group which tells me you have a great rifle. But then you decide to do the ladder and find

quote:

Shots 3,4,5 clustered and were at 43.4, 43.6, and 43.8 grains. I bumped my load to 43.6gr and went out this morning.........Shot that rediculous group in a 15mph crosswind from 10 O'clock...3 shots that are right at 1/2"!

which is also excellent. My question is what happened to the great group at the lower charge? Is it chopped liver now just because you read the tea leaves and have an epiphany?

Then there is

quote:

There have been some frustrations for sure like with my .264 Win Mag. I've shot ladders with 4 different bullets, picked nodes, loaded them and none have panned out. But I don't think it's the method

Are you just discounting this?

At 300 yards unless you are a dedicated benchrester then some shots are going to go up and down and sideways, some more than others. Evidence shot #7 which is way off shots #8 & #9 (but next time could land right between them and be the perfect Audette trio! ). Also there is not much more vertical dispersion between shots #10, 11 & 12 than there is between #3, 4 & 5, more horizontal but you said the wind was blowing so that shouldn't throw it out.

So it is all subject to interpretation and spin.

Do you think I used Audette to determine this load?


No, I did a ladder of increasing powder charges until I got to the velocity I wanted and dedicated all my other attention to case prep, bullet selection, gun maintenance and shooting form.

Now if you like Audette or OCW, great! But I'll bet you could have taken any of those loads and shot a great group.

JMHO

Hey woods,

I'd be interested in any data you have with the 30-06 and RL-17.

I'm really having some cognative dissonance with your post. Are you saying that if you have a good rifle, the amount of powder you put in the case doesn't matter for accuracy? All that is necessary is to find the velocity you want and then tune with seating depth? I tried that with some limited success with 3 factory rifles. I took 1 rifle and tried it with 3 different bullets and 1 bullet failed to be accurate. It also makes me wonder if this is your belief, why I took such a beating when I was experimenting with just that theory?

What about barrel harmonics and the optimum exit time for the bullet? That's what the Audette's test finds. If you don't have consecutive shots impact at the same POI, then it's not a tolerant charge weight range for your barrel assuming the barrel likes your bullet choice. I realize the possibility of chance impacts throwing the test askew, but obviously if that certain charge weight range has flyers, it's not THE LOAD. (could be the bullet, powder, etc...)

The 43 gr load is not chopped liver, but the 43.6 gr load derived from the Audette's ladder is definitely better as I have shot it out to 760yds to nail down the data. You know when you have found THE LOAD for your rifle; it has no vertical and the consistent repeatability from shot to shot is there...you have complete confidence derived from seeing the shot to shot consistency.

I shot the ladder in great conditions, so any horizontal is the load. The 1/2" 3-shot 300 yard group with the load chosen from the ladder was shot in a 15mph crosswind. I'm sure some luck was there, but I also shot steel out to 560 and it just built my confidence even more! I should correct myself by saying the group was fired at 300 meters or 330 yards. The load was center punching the bolts on the hangers even in the crosswind consistently. I truly don't believe I could have chosen any of the loads and shot a great group. Check that; the gun would not have shot a group as good as the one I believe is the optimal for the barrel..

They all may be good, but not as good as the best load.

To find the best load with the components that work the best in your rifle, I steadfastly believe an Audette's test must be shot, evaluated, and a charge weight chosen from the cluster.

I find this very interesting. From what i have read of the Audette method, you are only shooting one shot at each charge weight. Seems like it would be very easy to have fliers and mess up the ladder unless your shooting in very controlled conditions. I do like the idea of the method though. Has anyone tried it by shooting 2 shots at each charge etc? This might help nodes be more obvious, although more components used as well. Any thoughts gentlemen?

For a very sophisticated version of the Audette method, search for Jason Baney's article on the 6mm BR website.

You may chose not to believe in the Audette ladder, but among those interested in ultimate long range accuracy, you'd be in the minority.

I applaud your effort, RC.

And appreciate your well reasoned posts.

flaco

Hey rc,

If you recall, my main objection to your previous assertion that you could find the best seating depth and then adjust powder charge as needed was that the powder charge had a much greater influence than the seating depth. So if you chose a seating depth first, then the accuracy could go to hell with increased charge weight. That seems to me to be consistant with finding the velocity I want and adjusting seating depth to fine tune. That was my premise all along. You caught flak because of your insistance that you could choose a seating depth first and that seating depth would be best throughout the velocity range for that bullet.

I'm with curtis in that flyers at 300 yards create a problem with the Audette. I think it would add a lot of credence to the test if there was a linear progression of the shots upward with each shot number in order and at a predictable distance above the previous one. Then if there was a group of shots that had a slightly less dispersion, then certain conclusions could be drawn.

It's just like in your test you picked shots 3, 4 & 5 but shot 4 was pretty far above 3 and 5 fell back down below 4. Is it possible that 5 was a bad shot and should have landed up around 7? And where is number 6?

Reading tea leaves bro'! Now remember that we are just having a lively discussion here and I am not casting dispersions on your experimental nature and quest for knowledge. Perhaps a little more data and trials would confirm or negate the results, that's all.

30-06 and RL17. I wanted to shoot the 200 gr Accubond at ~2725 fps (to fit the TDS reticle in the Kahles scope but that is another story). So that is the only bullet I have data on. But this is a prime example of the way I work up to a load (right or wrong I dunno but it works for me) by starting low and working up with groups


the next range day the long ranges were closed so the next loads were shot at 100 yds




Anyway, I could have picked some of the loads at a lower speed which were excellent but got the velocity I wanted with 55 gr so chose that for my load. Didn't have to tweak the seating depth which was .03" off on all of them.

Seems to me to be much more conclusive than running an Audette but it might be interesting to do an Audette after the fact to see what it says.

I have never tried audette but tonight loaded some rounds for my 6.5x55 and will give it a try the next chance i get to go to the range. I like the idea of it, but will have to give it a workout for myself and see what i think.

I could be wrong because most of my reloading experience is with pistols and even that is somewhat limited, but i think the most important thing is that the reloader use some method that is consistent and repeatable, then they should have a good shot at success. Do you agree?

quote:

Originally posted by rcamuglia:

quote:

By the esteAmed Mr. Woods: ...now you might say 5, 6 & 7 looks like an accuracy node or you might say 1, 2 & 3 look like one. But in reality I just picked a load that gave me the velocity I wanted, shot a 5 shot group just below it, a 5 shot group at that load and a 5 shot group just above it to check for general accuracy. Then adjusted the seating depth out till I got what I wanted. Ended up with a load close to #9 on my target.

This sounds a tad like my old, de-bunked theory about choosing a safe max load (the velocity you want) and doing the tuning with seating depth! What's up?! I'd hide behind the couch from HC after that one too! ...

Hey R, You need to realize that a small portion is missing - the Velocity Mr. Woods selected "was most likely" in the middle of a Harmonic Node. In his haste to do some sort of totally worthless "Thingy" Measurement, he probably just didn't realize it. May have been too much Cigar smoke in the way to see the Node.
-----

To top it off, I've heard his Dogs on the phone and the one in the flick looks like one of Mr. Woods dogs. If that fine specimen of womanhood has a broken hip, we could be positive.
-----

Concerning the Fliers, it can happen with any number of shots a person chooses to fire. If you know for a fact you caused a Flier, that is totally different from a Random Flier - which can be created by a myriad of things.

Only two things wrong with firing more than one shot at the same level and then "Stacking the Targets to locate the Harmonic Nodes - 1. it is often a waste of "Time" which causes the environmental conditions more "Time" to change and thus have a significant effect on the Points-of-Impact; 2. It is most often a waste of components - but does give you more Trigger Time.

Tuning to the a specific desired Velocity will work - if you do not care about Groups.

Hey HC, wondered how long it would take you to join the party.

quote:

Hey R, You need to realize that a small portion is missing - the Velocity Mr. Woods selected "was most likely" in the middle of a Harmonic Node.

Funny how that seems to happen everytime!

Wanna see some targets?

quote:

Concerning the Fliers, it can happen with any number of shots a person chooses to fire. If you know for a fact you caused a Flier, that is totally different from a Random Flier - which can be created by a myriad of things.

Sounds like an excuse to me! Use that one very often?

Personally I don't believe in called fliers unless in the event of an earthquake. Bad shots, sure. Called flyers? So one lands outside the group, is it only a called flyer before you look at it on the target or do you get to look and see you f'ed up and then call it a flyer??

quote:

"Time" which causes the environmental conditions more "Time" to change and thus have a significant effect on the Points-of-Impact;

Laying groundwork for more excuses?

quote:

Originally posted by woods:
...Sounds like an excuse to me! Use that one very often?

I use any one I can think of that sounds even 10% possible and plausable.

quote:

Personally I don't believe in called fliers unless in the event of an earthquake. Bad shots, sure.

Have had a good many due to "Cold Shivers". When the Temp drops way WAY down below 80deg, the "Chills" seem to hit.

quote:

Called flyers? So one lands outside the group, is it only a called flyer before you look at it on the target or do you get to look and see you f'ed up and then call it a flyer??

Everyone knows you are not supposed to "Blink" or take your eye off the Target when you shoot. It is considered proper Follow Through to keep watching the Target. Gets a bit tougher with Robust Cartridges, but you just have to buckle down and do it properly.

quote:

"Time" which causes the environmental conditions more "Time" to change and thus have a significant effect on the Points-of-Impact;

quote:

Laying groundwork for more excuses?

That is one of the many reasons the "ocw-fiasco"(plagerized from the never improved upon Creighton Audette Load Development Method) is hosed up. By the time a person gets through shooting all the Cartridges in the "ocw-fiasco", it may have gone from needing SPF-30 skin grease to needing longjohns.

But, that becomes obvious to the ocw-fiasco fan.

Hey, I think OCW is like reading tea leaves also.

So it is your premise that if you sight a gun in at 300 yards at.....say 80 degrees and then go hunting in 50 degrees, that you are going to have " a significant effect on the Points-of-Impact"? Not in my experience. My shooting is from October to June and mostly during the cold months but I have not seen any significant POI change from say.....40 degrees to 80 degrees. If it did I would be looking for reasons!

Maybe you need to try some RL powders.

I think Audette could provide some useful information about accuracy nodes if you did 3 of them exactly alike on 3 different days and came out with the same approximate shot placements and correlations between subsequent groupings. Or, like I said previously, you had an extremely accurate benchrest rifle. Most hunting guns (and shooters), even very accurate ones are not dependable enough to draw conclusions from one test.

But one test? Naaah, reading tea leaves.

Great discussion Gentlemen, oh, and woods and HC too! Ha! (Geez, it's just a joke!..)

quote:

Hey rc,

If you recall, my main objection to your previous assertion that you could find the best seating depth and then adjust powder charge as needed was that the powder charge had a much greater influence than the seating depth. So if you chose a seating depth first, then the accuracy could go to hell with increased charge weight. That seems to me to be consistant with finding the velocity I want and adjusting seating depth to fine tune. That was my premise all along. You caught flak because of your insistance that you could choose a seating depth first and that seating depth would be best throughout the velocity range for that bullet

You're right, that's what my hypothesis was. I'm not sure if I proved it wrong though. What I was doing was essentially what you are doing except I never shot a test to find velocity first. I simply chose a charge close to max published, loaded it and adjusted seating depth to get the best accuracy. It worked OK but failed on one bullet out of three in the same rifle. I think the barrel didn't like the bullet.

quote:

I'm with curtis in that flyers at 300 yards create a problem with the Audette. I think it would add a lot of credence to the test if there was a linear progression of the shots upward with each shot number in order and at a predictable distance above the previous one. Then if there was a group of shots that had a slightly less dispersion, then certain conclusions could be drawn.

Due to barrel harmonics, I have never seen a nice neat linear progression upward for impacts except in the target you posted. Sometimes higher velocity shots hit lower than lower velocity shots like jeffeosso says. I think generally higher velocity shots hit higher on the target, but there is always some unpredictable impacts and I don't believe they are due to anything but barrel harmonics. That's why the test is so useful. In the '06 OCW targets you posted, you found one that grouped OK. But how do you know that is the most accurate long range load; the load where the bullet is exiting the barrel where it is the most calm? To me, at 100 yards you have way too much vertical dispersion with the load you have chosen; at least a minute. The long range Audette's test ferrets that out and you choose your load based on the cluster.

quote:

It's just like in your test you picked shots 3, 4 & 5 but shot 4 was pretty far above 3 and 5 fell back down below 4. Is it possible that 5 was a bad shot and should have landed up around 7? And where is number 6?

The total vertical was around an inch at 300 yards....pretty damn good!

quote:

30-06 and RL17. I wanted to shoot the 200 gr Accubond at ~2725 fps (to fit the TDS reticle in the Kahles scope but that is another story). So that is the only bullet I have data on. But this is a prime example of the way I work up to a load (right or wrong I dunno but it works for me) by starting low and working up with groups

That's fine. But with the Audette's ladder you use less shots, find the nodes, and find the max load all in one test! Brilliant!

quote:

Hey R, You need to realize that a small portion is missing - the Velocity Mr. Woods selected "was most likely" in the middle of a Harmonic Node.

Without shooting the Audette's ladder, he'll never know. I would say it is not, with that much vertical dispersion because the bullet is obviously exiting the barrel when it is pointing in different places. A good load in the middle of the harmonic node will have insignificant vertical dispersion. To me 1 MOA is significant. 5" at 500, 10" at 1000


Here's some pictures of Audette's tests with 3 different rifles then the picture of a group shot with the load I chose from the middle of the node from the Audette....tell me it doesn't work.



Mod 70 Winchester Classic Sharpshooter Audette shot at 500 yards:





The corresponding group chosen from the node shot at 300 yards:






.243 WSSM A-Bolt Audette at 300:






A group with the load chosen from the middle of the node:






And the 6.5 Creedmoor:





And its corresponding group shot at 300....

If you say so.

See the thing is you can look at those tests and see a pattern because you want to see a pattern. I can look at them and see all kinds of inconsistancies and anomalies.

Spin and tea leaves.

Yes, the pattern is that when a load is chosen from the middle of the properly identified node cluster, it generally is THE long range load for your rifle!

Is the pattern you look for 3 or 4 shots in more or less the same area or 3 or 4 shots that show a slow progression up the target?

I have looked for at least 3 shots clustered close together with as little vertical dispersion as possible. If you pick a load in the middle of the cluster by charge it seems to work. You know how a good load will be somewhat tolerant to a slight increase or decrease in charge? That's what I look for.
Notice on my 300 WM ladder at 500 there are 5 consecutive shots that cover more than 1 grain of powder that impact in basically the same place. That's a damn good load that you can be confident in. You may even not have to weigh every charge; just throw them it's so tolerant!

What Mr. Audette's test accomplishes when you learn to read the tea leaves is a load that has insignificant vertical dispersion.

Why on earth would you want a load at any velocity with which you not only have to worry about making an accurate wind call BUT ALSO worry about if the barrel decides to throw the bullet high or low as well?

The wind is tough enough to judge!

Now if you're just shooting game out to 300 a load that has a minute of vertical is fine, but for shooting small targets out to say 1000, it makes a big difference. I want even my hunting loads and guns to be the best they can be.

The Audette's ladder makes it possible.

quote:

Originally posted by woods:
So it is your premise that if you sight a gun in at 300 yards at.....say 80 degrees and then go hunting in 50 degrees, that you are going to have " a significant effect on the Points-of-Impact"? Not in my experience. My shooting is from October to June and mostly during the cold months but I have not seen any significant POI change from say.....40 degrees to 80 degrees. If it did I would be looking for reasons!

Maybe you need to try some RL powders. ...

Mr. Woods, You are indeed a Master at skewing what has been said. Did you take lessons from "my Hero" teenScum?

As I'm sure everyone following this thread knows, I was talking about Fliers being created, not the entire Group shifting.

If you would shoot beyond 30yds, you might see what R and I are talking about. Then again, maybe not.

RL Powders??? Naw, already wasted enough money on them.
-----

quote:

Whammed in by R:
What Mr. Audette's test accomplishes when you learn to read the tea leaves is a load that has insignificant vertical dispersion.

Why on earth would you want a load at any velocity with which you not only have to worry about making an accurate wind call BUT ALSO worry about if the barrel decides to throw the bullet high or low as well?

The wind is tough enough to judge!

Excellent Grasshopper, just excellent!!!

I've only been reloading for accuracy for about 5 years. Before that my reloading was to save money. I used to shoot lots of prarie dogs with my 22-250 and clays birds with a shotgun.

I first worked up loads like woods by loading 3 at this charge, 3 at the next, etc and shooting them. Then, as you know, while working the load for my .243 WSSM, discovered that with the proven load when the seating depth was wrong it did not shoot accurately at all. This is when I thought I found the shortcut. Just load to the velocity you want (around max for the gun) and tune with seating depth. Sometimes it works, sometimes it doesn't. When it works, the accuracy is only fair unless you get lucky.

Since then I've really discovered the Audette and have a love affair with it. That's why I want to marry Audette's Daughter.

Like woods and others advice here, I just load the test rounds at .030" off the lands and shoot the test. If you have clusters, the barrel likes the bullet and components. If there aren't any easily recognizable clusters, try another bullet and do it again....The resulting loads are as accurate as the gun can be.


What has continued to amaze me as I talk to rifle shooters here and in my city who have been shooting and reloading for accuracy for many more years than I have, is that very few use or even know about the Audette's test. Even my gunsmith. I'm quite astounded to say the least that they don't know about or use the absolute best tool in the bag for finding the accurate load.

woods,
This will be tough for you I have a feeling, but hear this out and then just try it.

Get some fire-formed brass without doing any of the meticulous case prep that you normally do. I bet if you run Audette's ladders with cases like these you will find that the resulting accurate loads will tell you that you need not to be so meticulous as you have been.

Not a ding on your work, it can only help the load. I neck turn, flash hole de-burr, uniform primer pockets as well.

Here's an Audette I shot with my 22-250.
I haven't as yet loaded any ammo in the nodes to check accuracy as the rifle is having some scope work done.


Can you read the tea leaves?






This is how I read the leaves..............







There are three possible accuracy nodes. Soon I'll be able to try them.

Ok here is what works for me, which I guess is a combination. I choose a seating depth for the bullet I am wanting to use which will function reliably from the magazine no matter how fast I try to cycle them. I have a couple of rifles which with certain bullets this does make a difference.

After setting this depth I shoot increasing charges until I get to the max load for that combination. Usually my targets look like this,



All spots on the right side were factory loads or fouling shots. The two larger spots on the lower left were the final load only with two different primers. In both 5 consecutive shot groups, shots 1-3 are clustered 4 and 5 are from the barrel heating.

I have found that depending on the powders burn rate or load density that the most accurate load will vary. For this I try to pick powders which are on the slower end for the particular case capacity in order to keep the load density higher. This usually gives me the higher velocity with the best accuracy. Like I said usually. I generally have a minimum acceptable velocity I want to use in mind, and if I don't get close I will swap powders. Using this 8 out of 10 times, the loads will come together into an acceptable range on the upper end with the bullet I am wanting to use for that particular rifle.

Now not using ladders to my knowledge except to reach high objects or Audette, this is how I have been working up loads since I was taught by my pop many years ago. Right wrong or indifferent it works for me, and has held the accuracy on the loads I have worked up using it.

quote:

Originally posted by woods:
So it is your premise that if you sight a gun in at 300 yards at.....say 80 degrees and then go hunting in 50 degrees, that you are going to have " a significant effect on the Points-of-Impact"? Not in my experience. .....I have not seen any significant POI change from say.....40 degrees to 80 degrees. If it did I would be looking for reasons!

You better believe there will be a point of impact change
Temperature as well as other atmospheric conditions effect POI! The effect can easily be seen when shooting a match that starts at around 40 degrees and ends at around 90.

I guarantee that a 700 yard target at 40 degrees has more come-up clicks from the 100 yard -0- than the same target at 80 or 90 degrees. If you haven't shot a match such as the SRM and experienced it for yourself, all you have to do is run the numbers on JBM and input different temperatures...


In short, as the temperature increases your POI gets higher.

quote:

Effects of Temperature on Velocity and Pressure

Velocity and pressure are both measurably affected by temperature.

The following chart was worked out by the famous big game hunter, Les Bowman, of Cody, Wyoming. Les has the following to say about this effect:


"Few handloaders realize the difference temperature of powder makes in velocity and pressure. And the funny thing is that the top temperatures, that is from 72 degrees normal to 100 degrees for instance, affects pressure more than from 70 degrees down to zero. As you will notice in the chart, there is a 129 fps minus for the zero temperature reading at 4000 fps bullet speed, and 155 fps plus for the temperature about 70 to 100. Many sight in one day when it is a certain temperature and later, when temperatures are perhaps 50 degrees different, they think their scope has changed when groups print at a different place. Also maximum loads worked up at, say 40 degrees, can be really dangerous at 90 or 100 degrees. It's the powder temperature that counts, not the temperature of the outside air. I have had a lot of correspondence with DuPont and was told by them that they figure 60 p.s.i. in pressure difference for every degree in powder temperature change. In the case of the 4,000 fps above at 155 on the high side and 129 on the low, or a difference total of 284 fps, that would make 17,000 pounds difference in pressure. This is the correction chart I use, and while I do not claim it is absolutely right, it is close."


Temperature Correction Chart Used by Les Bowman


Add This To Tested Velocity Tested Temp Subtract This From Tested Velocity
100'F 90'F 80'F 70'F 60'F 50'F 40'F 30'F 20'F 10'F 0'F
85 56 24 2300 18 36 50 54 57 66 80
90 58 25 2400 19 37 50 56 60 70 84
96 60 26 2500 20 38 51 58 65 77 88
101 62 27 2600 21 39 52 60 69 89 89
105 64 28 2700 22 40 54 62 71 81 90
108 65 28 2800 23 41 56 68 77 85 91
112 66 29 2900 24 43 58 70 78 88 94
116 68 30 3000 25 44 60 73 83 91 97
121 71 32 3100 25 45 61 74 85 93 98
124 73 32 3200 26 47 63 77 92 96 102
126 75 33 3300 27 48 66 82 94 101 106
132 77 34 3400 28 50 68 82 94 102 110
135 79 35 3500 29 52 70 85 86 106 113
140 82 37 3600 29 52 71 86 98 108 115
144 86 38 3700 30 54 73 89 101 111 119
147 87 39 3800 31 56 74 91 104 114 123
151 89 39 3900 33 57 78 94 107 118 126
155 91 40 4000 33 59 80 97 110 121 129



Copyright 1998-2010 Stephen Ricciardelli

quote:

You better believe there will be a point of impact change
Temperature as well as other atmospheric conditions effect POI! The effect can easily be seen when shooting a match that starts at around 40 degrees and ends at around 90.

I guarantee that a 700 yard target at 40 degrees has more come-up clicks from the 100 yard -0- than the same target at 80 or 90 degrees. If you haven't shot a match such as the SRM and experienced it for yourself, all you have to do is run the numbers on JBM and input different temperatures...


In short, as the temperature increases your POI gets higher.

I believe this is true, however it shows much more with some powders and calibers than with others.

Just using my own loads, my 25-06 using RL-22 show very little if any differences out to 400yds in avreage temps from 30 to 90 degrees. However, the same bullet case and primer loaded with IMR-4831 to the same FPS, shows a dramatic change from POI.

This has also shown true with a couple of other powders like the load of IMR-4350 I use in my 30-06 shoots the same in the above mentioned temps, however the same bullet case and primer used with H-4831 shows a 2" difference form the high temp to the low temp, as does a load of IMR-4350 compared to a similar velocity load of Ramshot Hunter in my .270 Win, where the IMR drops off more.

To say however that across the board every single powder and caliber will react the same, IMO is a reach. In the past few years there have been real progressions made to keep things on a more stable basis with several of the larger named powder companies. There is still some variance , but not nearly as much as there was 10 years ago. Also for most people who think that 300yds is too far to be shooting at anything in the first place,much less 700, and they would never notice the minute differences in temp at 100yds as it would most likely be lost in the noise of their group.

Now someone who has spent more on one rifle package than most will on three, will probably notice. However these rifles are not hunting rifles and rarely seen in the field shooting other than in competition.

You have to remember that 95% of the folks here rarely shoot more than 300yds in the first place, and most of those condemn those of us who do, especially if it is in a hunting situation.

True