Mikecr
Well-Known Member
You're delusional B_RAD
Seriously,, consider it
Seriously,, consider it
ladder test help.....
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SBruce
Well-Known Member
A 5-shot sample's not a big one. It only means its size represents what accuracy will be for all shots fired about half the time. If you want really good samples, that is those that are 80% representative of what your rifle's accuracy is, shoot 20-shot ones.
Just how many variables are there with 5-shot groups compared to 20-shot ones? What are those variables? I'm curious as to what you think the variables are.
Tikkamike
Well-Known Member
you misunderstand what I am saying, I am all for 20 shot groups, in fact that takes out variables. 5 shots is minimum but what I use a lot of times because i dont have the time to shoot 20 shots a lot of times. the variables I am talking about is doing my initial load development at 2-300 yards rather than 500+ that way im taking out environmental variables with the closer range. THEN once I narrow my results and think I have a good load I play with it at about 5-600 and 1000. I shoot a lot of Tikkas and those light little barrels heat up after 2 shots so it would take me ALL day to get 20 shots out of them, so I have just become accustomed to shooting several 5 shot groups. And I wouldnt say a 5 shot group is small most of my rifles shoot under .5 i went out and re zeroed my 338 lapua last night after swapping rings and base and at 200 yards it shot a .25" ragged hole with 5 shots, i dont really feel any further testing is needed.
rscott5028
Well-Known Member
Ladder tests are one of many tools/methods for getting to a load that you want to continue working with and practicing with.
More information is better than less information, including MV, number of groups, shots per group, shooting in varying conditions and at varying ranges, cold bore POI, etc...
Sensible load development that coincides with practice and building confidence is not wasting barrel life.
Shooting lots of ammo without a method that demonstrates that the load does what you intend is wasting barrel life.
The OP started out on the right track. He simply needs to continue.
-- richard
More information is better than less information, including MV, number of groups, shots per group, shooting in varying conditions and at varying ranges, cold bore POI, etc...
Sensible load development that coincides with practice and building confidence is not wasting barrel life.
Shooting lots of ammo without a method that demonstrates that the load does what you intend is wasting barrel life.
The OP started out on the right track. He simply needs to continue.
-- richard
Light weight, slender, whippy barrels that don't shoot accurate after heating up are not a problem. . . . . . .if they're fit to a receiver that's had its face squared up with the barrel tenon and chamber axis. It's not the barrel's fault if zero changes as they heat up. The receiver's not trued up properly. And virtually all factory rifles are in this category.
Tikkamike
Well-Known Member
Let me start by saying I am no barrel expert by anymeans, however I have an extensive back ground with fabricating and heat treating aircraft parts. that being said I disagree.
Not completely though. I agree a consentric rifle from end to end will induce accuracy however the fact that factory barrels (all to my knowledge) are NOT heat treated and stress relieved, which means as things heat up the "grains so to speak" of the iron which have been moved around with all the cold working are all moving and expanding. in different directions. Since it is tied in to the rifle on the breech end you see all of the movement on the muzzle end. which causes your point of impact to walk.
Now with a concentric action, bolt, threads, chamber bore etc.. and a properly stress relieved barrel you should (in theory) be able to shoot without your point of impact changing of course you still have to deal with imperfect brass and all those other variances in your ammunition and of course changes in bore dimension from heat expansion whatever factors happen to come into play in that specific situation... so YES it is the barrels fault.. weither its entirely the barrels fault or not changes from rifle to rifle.
I don't think actions and cases have to be perfect.
Primers and powder charges aren't perfect; fixed amounts of their main ingredient causes muzzle velocity spreads. And cases don't have to be perfect; a couple thousandths spread in body and shoulder wall thickness doesn't matter. Case necks are fine if their thickness doesn't have more than half a thousndths spread; they can be fired in chambers with several thousandths clearance to the chamber neck and all shoot just fine.
The smallest series of 10-shot test groups at 600 yards I know of were shot back in 1970. An old classic Win. 70 pre-64 action with a sloppy bolt fit that wasn't in perfect alignment with the barrel tenon thread axis was used, but the Hart barrel's bore, chamber and tenon axes were all in perfect alignment. And the receiver face as well as the bolt face were squared up with the chamber and tenon axes. Western WCC58 cases were used holding IMR4064 powder; I forget what primer was used. The FMJBT bullets used were spun at 30,000 rpm checking for ones that were perfectly balanced as indicated when current to the motor was steady at its lowest reading. Maybe 10 out of a box of 100 were so balanced. Some of the others flew out of the collet held in a Dremel Moto Tool 'cause they were so unbalanced.
Several (more than 5 or 6) sub 1.5 inch groups were fired, each starting with a cold barrel. They ranged from 1.5 down to about 0.7 inch. These "perfect bullets" fired in this test was the best thing done to show that best accuracy doesn't have to come from "perfect concentric actions" and "perfect cases." As long as the barrel, action and stock behave in their mechanical motion the same for each shot, best accuracy will prevail.
When someone proves that these new fangled solid round or square "perfect" actions made these days have to be used to shoot good bullets that well, they may have a point proven. Meanwhile, nobody's done that well since and maybe nobody ever will.
Well I'll step in... I shoot very very good groups with a Cooper, which has had everything "done" to it. My buddy shoots a stock Howa and his best groups are 3/8", Howa is a **** good gun, but it doesn't have the blueprinting, or hand lapped barrel... etc...
Moral - It does matter... How do you expect your reciever to react the same every time if it's not bedded? How about your barrel if it's not floated?
Moral - It does matter... How do you expect your reciever to react the same every time if it's not bedded? How about your barrel if it's not floated?
With all due respect of your skills and knowledge of the shooting sports, using the smallest groups that seldom happen is the worst way to describe them. They only happen the smallest percentage of the time.
Accuracy's best described by the largest group(s) fired. That's what one can count on all the time. If 3/8" happen once in a (great) while, the largest ones may be over 1". Tell me what the largest groups are so I'll get the truth about that Howa's real accuracy level.
Some rifles with clamped-in barrels that are not free floated do very well indeed accuracy wise. Consider the US military 7.62 NATO Garands and M14NMs that shoot no worse than 4 inches at 600 yards. They shoot 1/4 to1/3 inch at worst at 100 yards. All with non-lapped arsenal barrels using new commercial match ammo loaded with powder charges with a 1/3-grain weight spread.
Then there's rail guns used by benchresters (and Sierra Bullets) to shoot very tiny groups. Their barrels are clamped in a foot-long metal block and the receiver's free floating in the air behind the barrel. Such rigs shoot sub 2/10ths" groups all day long with good bullets.
rscott5028
Well-Known Member
BatrB,
Your point about smallest group vs largest group for a given rifle is well taken. ...although a bad shot or group may sometimes be due to the shooter or weather
The same applies to makes and models. One example of a Howa may not be representative of that make/model.
ditto for quoting the smallest groups from the best performing production rifles of any mfg
In any case, you don't have to have perfect data to spot trends that are worthy of further investigation whether it be a ladder test or make/model comparison.
-- richard
Just a question, but I was under the impression that when measuring "grouping", especially at longer ranges you should really only take in to effect for vertical stringing and ignore the horizontal displacement. Being that the wind is the only thing that really effects horizontal and a loads parameters have very little effect on the horizontal. I just wondered because of all the comments about wind at, in this case, 500 yards skewing the results.
Mikecr
Well-Known Member
I for one disagree with the vertical only presumption associated with tune.
Barrel muzzles can hold a rotational component, as well as whip.
This is another parameter that is to be observed with ladder testing.
Guess what,, it's right there..
Now I'll leave it to one of the BS-Bs to tell you nothing matters -but shooting a lot..
Barrel muzzles can hold a rotational component, as well as whip.
This is another parameter that is to be observed with ladder testing.
Guess what,, it's right there..
Now I'll leave it to one of the BS-Bs to tell you nothing matters -but shooting a lot..
Best way to show how barrels whip and vibrate is shown in the following link:
Barrel Harmonics Mode Shape Movies
While the vertical whip of a barrel from recoil causes the most angular change of the muzzle axis, there's still a little bit horizontally. Milli- and micro-scopically, there's movement at the fundamental frequency and its harmonics in all directions happening at multiples of the barrel's resonant frequency. The resonant frequency is low and typically less than 100 Hz or cycles per second. Bullets from centerfire rifles are long gone before the barrel goes through one cycle.
Variables that change how much the barrel whips and vibrates at this low one and the higher frequencies are caused by out of square case and bolt face, non-repeatable bolt lockup positioning, the angle of the recoil axis to the object mass (machine rest, free recoil on bags, held by a human) that holds the rifle. Most of the horizontal group variables are caused by this. Then there's the bullet; if unbalanced in any way, the centrifugal forces caused by its spin will move the bullet's flight axis away from the bore axis by some degree.
Other causes of greater vertical shot stringing are a weak firing pin spring not detonating the priming compound uniformly. Powder charge position in the case. How hard one holds the rifle against their shoulder; a 100 fps spread across two folks shooting the same rifle-ammo combo and one person producing smaller standard deviation in velocity has been proved many times over. Check some ballistic tables and note the difference in bullet drop down range for a 20, 40 and 60 fps spread in muzzle velocity; it's a couple tenths of an inch at 100 yards, a couple dozen inches at 1000.
At my request, software was written by Tom Irvine at the following link to calculate the natural or resonant frequency of rifle barrels. It provided answers for a 2 and 3 taper barrel by entering the diameters at different points, their spacing and the bore diameter. It's available at:
http://www.vibrationdata.com/updates.htm at about 2/3rds down this page.
Note that when you screw the chambered barrel in a receiver, fit the barreled action to the stock then mount a scope on it, the fundamental of the barreled action will change a small amount. But it does show the differences between different caliber and barrel contours for different lengths. An interesting thing to check out.
Barrel Harmonics Mode Shape Movies
While the vertical whip of a barrel from recoil causes the most angular change of the muzzle axis, there's still a little bit horizontally. Milli- and micro-scopically, there's movement at the fundamental frequency and its harmonics in all directions happening at multiples of the barrel's resonant frequency. The resonant frequency is low and typically less than 100 Hz or cycles per second. Bullets from centerfire rifles are long gone before the barrel goes through one cycle.
Variables that change how much the barrel whips and vibrates at this low one and the higher frequencies are caused by out of square case and bolt face, non-repeatable bolt lockup positioning, the angle of the recoil axis to the object mass (machine rest, free recoil on bags, held by a human) that holds the rifle. Most of the horizontal group variables are caused by this. Then there's the bullet; if unbalanced in any way, the centrifugal forces caused by its spin will move the bullet's flight axis away from the bore axis by some degree.
Other causes of greater vertical shot stringing are a weak firing pin spring not detonating the priming compound uniformly. Powder charge position in the case. How hard one holds the rifle against their shoulder; a 100 fps spread across two folks shooting the same rifle-ammo combo and one person producing smaller standard deviation in velocity has been proved many times over. Check some ballistic tables and note the difference in bullet drop down range for a 20, 40 and 60 fps spread in muzzle velocity; it's a couple tenths of an inch at 100 yards, a couple dozen inches at 1000.
At my request, software was written by Tom Irvine at the following link to calculate the natural or resonant frequency of rifle barrels. It provided answers for a 2 and 3 taper barrel by entering the diameters at different points, their spacing and the bore diameter. It's available at:
http://www.vibrationdata.com/updates.htm at about 2/3rds down this page.
Note that when you screw the chambered barrel in a receiver, fit the barreled action to the stock then mount a scope on it, the fundamental of the barreled action will change a small amount. But it does show the differences between different caliber and barrel contours for different lengths. An interesting thing to check out.
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