Bob Kingsbury
New member
Exactly what are we looking for in a ladder test?
Ladder Test
- Thread starter Bob Kingsbury
- Start date
Bob Kingsbury
New member
is a chronograph really any use in this
M
mike in co
Guest
ARE WE TALKING SHORT RANGE BR ?
we had some disscussion on the 600/1000 board, some productive, some a waste of bandwidth by a non-BR shooter blowing his own horn.
at 600 plus more concern with the group with the least vertical, at short range, small groups. remember it is only the first step in load development, not the last. helps to find a velocity if you are looking for one or two windows. is a chrono "necessary" ....no, can you learn more with one, most of the time yes. not so much about chasing numbers, as spotting errors.
not sure the lemmings need to do it with 6ppc/n133 as there is so much "known" data.
its a good tool when starting with a blank sheet of paper...new gun/new chamber/new powder/new bullet.
mike in co
we had some disscussion on the 600/1000 board, some productive, some a waste of bandwidth by a non-BR shooter blowing his own horn.
at 600 plus more concern with the group with the least vertical, at short range, small groups. remember it is only the first step in load development, not the last. helps to find a velocity if you are looking for one or two windows. is a chrono "necessary" ....no, can you learn more with one, most of the time yes. not so much about chasing numbers, as spotting errors.
not sure the lemmings need to do it with 6ppc/n133 as there is so much "known" data.
its a good tool when starting with a blank sheet of paper...new gun/new chamber/new powder/new bullet.
mike in co
John Kielly
Shari's fan club
No.
The ladder tests identify loads which, contrary to logical expectations, coincide at the same point of aim. Listening to sages on this site, it is likely that the trauma of firing these particular loads results in them exiting the barrel just after it has pased thru peak upward vibration. As a result, the progressive downward movement of the barrel compensates for the progressive flatter shooting of the loads as velocities go up.
On the other hand. it might occasionally mean that you have reached Oh Dear loading density & you just aren't getting any more velocity with your incremental load weight. Generally, it's unlikely that you go past this point too often.
Ladder load selection is the concept that permits centrefire benchrest shooters to load with powder throwers, rather than more precise devices, as they know that they've achieved a sweet spot that will stand loads being plus or minus a tad. This is achieved by going with the midpoint load of the coincident grouping shots.
Sweet spot loads quite possibly will not have the ultimate velocity spreads & standard deviations compared to others in the same loading sequence, but will be selected because they are in that pattern of tight vertical grouping. This doesn't mean that they aren't well crafted loads nevertheless.
Now, what interests me as a retired centrefire benchrester in good standing is whether you ladder test at 100 yards, with the mathematical probability that the 200 yards grouping will have an element of vertical or test at 200 in the expectation that most shoot better at 100. Or do you take it the next step & use a tuner to fair out the ladder loads.
The ladder tests identify loads which, contrary to logical expectations, coincide at the same point of aim. Listening to sages on this site, it is likely that the trauma of firing these particular loads results in them exiting the barrel just after it has pased thru peak upward vibration. As a result, the progressive downward movement of the barrel compensates for the progressive flatter shooting of the loads as velocities go up.
On the other hand. it might occasionally mean that you have reached Oh Dear loading density & you just aren't getting any more velocity with your incremental load weight. Generally, it's unlikely that you go past this point too often.
Ladder load selection is the concept that permits centrefire benchrest shooters to load with powder throwers, rather than more precise devices, as they know that they've achieved a sweet spot that will stand loads being plus or minus a tad. This is achieved by going with the midpoint load of the coincident grouping shots.
Sweet spot loads quite possibly will not have the ultimate velocity spreads & standard deviations compared to others in the same loading sequence, but will be selected because they are in that pattern of tight vertical grouping. This doesn't mean that they aren't well crafted loads nevertheless.
Now, what interests me as a retired centrefire benchrester in good standing is whether you ladder test at 100 yards, with the mathematical probability that the 200 yards grouping will have an element of vertical or test at 200 in the expectation that most shoot better at 100. Or do you take it the next step & use a tuner to fair out the ladder loads.
M
mike in co
Guest
ACTUALLY ladder testing is reccommended at 200 yds to be able to "see" as much movement as practical.( yes i do a lot at 100, then move to 200).
mike in co
mike in co
Boyd Allen
Active member
John,
Assuming frequency to be a function of the barrel, rather than the load (Plucking the guitar string harder doesn't change the note.) The sort of compensation that you wrote of would happen before the peak, not after, since slower shots would exit later in the cycle than faster ones , and therefore be aimed slightly higher, compensating for their less flat trajectory...I think.
Boyd
Assuming frequency to be a function of the barrel, rather than the load (Plucking the guitar string harder doesn't change the note.) The sort of compensation that you wrote of would happen before the peak, not after, since slower shots would exit later in the cycle than faster ones , and therefore be aimed slightly higher, compensating for their less flat trajectory...I think.
Boyd
Bob Kingsbury
New member
Boyd, I think it is the barrel that determines the frequency. But
I don't think a barrel resonates at the same frequency
at all temperatures. This can easily be tested. I wonder
if anyone has?
Thinking further, I don't believe the column of air
in the barrel is un effected by the temperature of the
steel. That column is replacing itself continuously and is
rarely stationary between shots. So the density of that
air must change
I don't think a barrel resonates at the same frequency
at all temperatures. This can easily be tested. I wonder
if anyone has?
Thinking further, I don't believe the column of air
in the barrel is un effected by the temperature of the
steel. That column is replacing itself continuously and is
rarely stationary between shots. So the density of that
air must change
John Kielly
Shari's fan club
Boyd,
But the later shot in a ladder test should have the higher velocity, being the heavier load & therefore must eject on the downswing to coincide, I hope.
John
Pete Wass
Well-known member
A friend showed me - -
A graph he had done doing the "lader Test" on the barrel he was shooting this past weekend. Seen on a graph, one can see where the swing of the barrel is and where the nodes appear AND - - how wide they are. It was interesting - -. I have been chasing the "upper Load Window" for years now and have recently begun to wonder if I was going in the wrong direction. I became interested in the Ladder Test to use to see which way to go.
I think I sort of do the same thing the way I tune. I shoot three shot groups and when the small colverleafs begin to appear, I think is seeing a node appear. What is disconcerting is the small round hole usually appears at the upper end of the nodes. That makes them difficult to maintain. ( shooting BIG 30 Cal rifles her folks)
A graph he had done doing the "lader Test" on the barrel he was shooting this past weekend. Seen on a graph, one can see where the swing of the barrel is and where the nodes appear AND - - how wide they are. It was interesting - -. I have been chasing the "upper Load Window" for years now and have recently begun to wonder if I was going in the wrong direction. I became interested in the Ladder Test to use to see which way to go.
I think I sort of do the same thing the way I tune. I shoot three shot groups and when the small colverleafs begin to appear, I think is seeing a node appear. What is disconcerting is the small round hole usually appears at the upper end of the nodes. That makes them difficult to maintain. ( shooting BIG 30 Cal rifles her folks)
Boyd Allen
Active member
A lower velocity shot must be pointing higher than one of higher velocity to hit the same spot, and it will take longer to reach the muzzle than one of higher velocity. So, as the barrel is swinging up the faster one will exit when the barrel is at a lower position, and the slower when at a higher position. Lower comes before higher on an upswing. On the down swing, the opposite is true. The faster shot leaves the barrel earlier in the cycle when the barrel is pointing higher, and the slower shot, later when pointing lower, thus adding to the vertical caused by the differences in drop of the different velocities.
Pete Wass
Well-known member
Lower is relative - -
The quest I have been on is to shoot as accurately as I could at the fastest speed possible. It seems that the faster one goes, the narrower the nodes become. The slower speed is relative in those terms. 3100 is slower than 3300 so the 3100 shots should be lower than the 3300 shots, no? If this is so then there should be points as fast as one goes where bullets exit the barrel lower than others, aye?
The quest I have been on is to shoot as accurately as I could at the fastest speed possible. It seems that the faster one goes, the narrower the nodes become. The slower speed is relative in those terms. 3100 is slower than 3300 so the 3100 shots should be lower than the 3300 shots, no? If this is so then there should be points as fast as one goes where bullets exit the barrel lower than others, aye?
Bob Kingsbury
New member
Pete, it just depends
John Kielly
Shari's fan club
Boyd,
I understand what you are saying now, viz that barrel displacement is a function of (barrel) time, & barrel time, of velocity. I have assumed that at the relatively close velocity increments we are discussing there was an element of independence & thus sweet spots were just a happy chance.
Maybe I should read more Varmint Al.
John
I understand what you are saying now, viz that barrel displacement is a function of (barrel) time, & barrel time, of velocity. I have assumed that at the relatively close velocity increments we are discussing there was an element of independence & thus sweet spots were just a happy chance.
Maybe I should read more Varmint Al.
John
Pete Wass
Well-known member
Boyd Allen
Active member
John,
Now you have it
, and yes you should, it is worth the time (I think). There are other things going on, but as far as bullet exit and barrel swing, I think he has it right.
Now you have it
, and yes you should, it is worth the time (I think). There are other things going on, but as far as bullet exit and barrel swing, I think he has it right.