One of two things CAN(not necessarily the case) happen at 400 yards. One if the load is really good it will be hard to see a difference. Two if the rifle is not capable of small groups it is still hard to see any difference in vertical due to velocity. I do mine at 690 and 875. None of my rifles shoot over .5 moa so I can not say for sure but if down correctly I would think a .75 moa rifle would show you the load at longer distance.
Accuracy due to velocity, charge, or random...?
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One of two things CAN(not necessarily the case) happen at 400 yards. One if the load is really good it will be hard to see a difference. Two if the rifle is not capable of small groups it is still hard to see any difference in vertical due to velocity. I do mine at 690 and 875. None of my rifles shoot over .5 moa so I can not say for sure but if down correctly I would think a .75 moa rifle would show you the load at longer distance.
Here is another way to do it also, has to do with the speed . Author claims he can get the same accuracy from different powder types just by matching the previous most accurate speeds. http://www.65guys.com/10-round-load-development-ladder-test/
Anyone who is trying to work up the most accurate load would defiantly minimize the chance of wind and opt out on such test during windy conditions ! Wind can and does have a vertical impact as well as side to side . Some rifles have heavy tooling Marks in the bore and accuracy can start to degrade in 15-20 shots or less , others may not happen till 500 or more . Round robin helps to minimize that too . Testing is done 300-500 yards is ideal but 100 also works if you know how to read the data. http://optimalchargeweight.embarqspace.com/ocw-vs-ladder/4529811360
ar10ar15man
Well-Known Member
says an almond grower, everyone knows they are nuts!
says the walnut grower.
round robin is just a waste of time powder and bullets, an opportunity to add bs to your data.
says the walnut grower.
round robin is just a waste of time powder and bullets, an opportunity to add bs to your data.
Says the one who does accuracy testing in the wind ...... talk about bs data
dfanonymous
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Worst part of reloading and shooting high volume in my opinion.
crkckr
Well-Known Member
Smokey3, I have had 2 different rifles where I tried the matching trick, which I had read about years ago but I sure couldn't duplicate their results, in fact if anything, accuracy took the proverbial basket ride! I had the velocities as close to exact as I could get but the accuracy was never even close to the same (using some of the same powders mentioned in the article, too). I'm talking about going from an inch to 2.5 or 3" which is disheartening to say the least. One was my 270 Win which, while not a benchrest gun, shoots better than most factory rifles of It's vintage. Maybe the "precision" rifle part has something to do with it? I may give this another shot with my latest rifle, an R700 with a trued action & custom barrel... but it's going to be a while before I can get around to it. Of course, I'm also dealing with a pretty small sample of just 2 rifles. Plus it could just be rotten luck... I've had a bit more than my fair share of that!
Cheers,
crkckr
Cheers,
crkckr
DUSTY NOGGIN
Well-Known Member
although vibrations, bouncing back and forth through a barrel will give a "lack of vibration at the muzzle" accuracy node, the heavier contour the more mass or area of metal, the bigger the nodes are ... i think vibrations are being slowed by the area of the barrel material ... im mot sure how big the difference would be but i would bet there is a difference between the speed the vibrations travel though different materials ((stainless vs. steel ))
either way velocity has to be timed to leave the muzzle at that "lack of vibration at the muzzle" time
so id agree that if your same rifle and load speeds up, as long as you are using the same everything brass primer bullet sizing capacity barrel and powder. you can get back to that accuracy node by adjusting velocity to time it again
i dont think 2 different barrel contours of the same length have the same vibration, velocity timing will be unique to each barrel. even if by chance they did end up same speed
my reason for this thinking is my small sample of heavy barrels seem to have accuracy nodes over a bigger change in powder charge , than the thinner sporter barrels.. i may need to get a larger sample to know for sure
either way velocity has to be timed to leave the muzzle at that "lack of vibration at the muzzle" time
so id agree that if your same rifle and load speeds up, as long as you are using the same everything brass primer bullet sizing capacity barrel and powder. you can get back to that accuracy node by adjusting velocity to time it again
i dont think 2 different barrel contours of the same length have the same vibration, velocity timing will be unique to each barrel. even if by chance they did end up same speed
my reason for this thinking is my small sample of heavy barrels seem to have accuracy nodes over a bigger change in powder charge , than the thinner sporter barrels.. i may need to get a larger sample to know for sure
crkckr
Well-Known Member
Does anyone remember the Houston Warehouse articles in Precision Shooting? Lots of very interesting info included in those articles, including some very specific info regarding barrel vibrations. Just do a Google search for Houston Warehouse shooting range. Ultimately they shot an .025" group at 325 yards! Makes for an intriguing read.
Cheers,
crkckr
Cheers,
crkckr
ar10ar15man
Well-Known Member
not so..you have mis-applied what i said.
ar10ar15man
Well-Known Member
benchrest central has a thread on the warehouse.
they did 100 yard shooting, inside a building.
you sure about the 325 yds inside ?
they did 100 yard shooting, inside a building.
you sure about the 325 yds inside ?
ar10ar15man
Well-Known Member
ok tuning/ tuning to a node is not JUST velocity.
if the bullet has a different bearing surface it changes time pressure
if the powder is different it can change when pressure is peaked which will change time pressure.
if the primer is different it may change the time that peak pressure is reached
so you can have the same velocity, and not be in tune
it just aint that simple
if the bullet has a different bearing surface it changes time pressure
if the powder is different it can change when pressure is peaked which will change time pressure.
if the primer is different it may change the time that peak pressure is reached
so you can have the same velocity, and not be in tune
it just aint that simple
MNbogboy
Well-Known Member
To the OP. After 50+ years of rolling my own I have to admit I am still learning. Your original questions are valid and yes I can see and have been through your frustrations. Yes there are nodes, yes they are pretty easy to find, but everything has to be controlled & verified to find them.
A good chronograph is important but with long range ladders not a necessity. But the chronos can help verify the good, bad and ugly. Good meaning a magneto speed or labradar. An optical if setup right in optimal light conditions will also work. I used shooting chronies for years and learned when and when not they are useful.
As others said quality of test loads is the most important.
Equipment obviously has to be in its best mechanical condition (ie; action bedding & torque, scope bases & rings etc.)
Shooter & bench systems also proper repeatable form.
That being said start with your best load so far and do a complete seating test from .010 off the lands down to say .120 off using 3 shot groups in .010 increments. Shoot these round robin in a fouled barrel. Don't let the barrel get hot. Then run a second test starting at .015 off to say .125 off again in .010 increments, also round robin. Most likely you will see 2 or more seating nodes with each test. Pay attention to the smallest groups and their point of impact in relation to the others (No scope adjustments during these tests).
After seating tests the OCW or ladder test can commence for velocity. Start again with your "good" load and load say 5 or 6 in each direction at .2 or .3 grain increments. Shooting the 10 or 12 now at a longer distance ladder (300-400) will show possible velocity nodes by verticle impact also chrono readings will verify the node. I've always recorded velocities but lately been graphing results. Nodes are clearly visible on graphs not necessary but really tell you where you are at. Once you identify the node or nodes you are almost there. Now you can fine tune your seating in .003" increments both directions. As you leave the seating node your groups open.
This whole thread has provided a ton of great advice and we hope we have helped.
Good luck and keep us posted,
Randy
A good chronograph is important but with long range ladders not a necessity. But the chronos can help verify the good, bad and ugly. Good meaning a magneto speed or labradar. An optical if setup right in optimal light conditions will also work. I used shooting chronies for years and learned when and when not they are useful.
As others said quality of test loads is the most important.
Equipment obviously has to be in its best mechanical condition (ie; action bedding & torque, scope bases & rings etc.)
Shooter & bench systems also proper repeatable form.
That being said start with your best load so far and do a complete seating test from .010 off the lands down to say .120 off using 3 shot groups in .010 increments. Shoot these round robin in a fouled barrel. Don't let the barrel get hot. Then run a second test starting at .015 off to say .125 off again in .010 increments, also round robin. Most likely you will see 2 or more seating nodes with each test. Pay attention to the smallest groups and their point of impact in relation to the others (No scope adjustments during these tests).
After seating tests the OCW or ladder test can commence for velocity. Start again with your "good" load and load say 5 or 6 in each direction at .2 or .3 grain increments. Shooting the 10 or 12 now at a longer distance ladder (300-400) will show possible velocity nodes by verticle impact also chrono readings will verify the node. I've always recorded velocities but lately been graphing results. Nodes are clearly visible on graphs not necessary but really tell you where you are at. Once you identify the node or nodes you are almost there. Now you can fine tune your seating in .003" increments both directions. As you leave the seating node your groups open.
This whole thread has provided a ton of great advice and we hope we have helped.
Good luck and keep us posted,
Randy
