ladder test phenomenon at 1000

[seymour fish]

Folks, Saw a striking phenom yesterday testing savage palma 1:13 30" at 1000. shooting blind, same point of aim for all shots, very mild condition, steady mirage from right at 4 mph, no gusts, any changes very gradual, kestrel 4-5 mph at firing point, survayors tape at 500, 750, 1000 in agreement at 45 degrees out. 168 hybrids .005 off. lapua necksized .0025 tension. 8208 xbr: start 40.5 gr and increasing by 0.3 gr sequentially. 3 shots each powder chg. looking to find node via studying the upward barrel whip less the predicted increased hight. of POI due to increasing speed. results: #1=8' group with 4' vertical, #2=up 8" with 5" group, 2" vertica;l#3=up 20" from #2, with perfect waterline and 5 MOA HORIZONTAL SPREAD. #4= up another 5" with group 3/4" by 1-1/2 " wide. #5= so excited the scope got me, but up additional 4", group 3" vart by 7" horizontal. #6=up additional 3-1/2" , group 1-1/2" vert by 3" wide. #7=in the same group but enlarged to 5" vert. Thoughts: first, have never seen or heard of a horizontal scatter of this magnitude with absolutely no change in conditions. consider blunderbuss effect of 4th wave at the muzzle on bullet exit ie worst possible barrel time. Second, startled to see the very next incremental charge group so tightly. Third, once chrono these loads and back out the expected vertical increments due to increasing muzzle velocity, expect to find a node across 0.6 gr of powder. this to be done today and calculated. Fourth, appears the 6th and 7th iterations at same elevation will indicate either a rolling off the top of the barrel whip sinewave, or a powder plateau where an increase in charge weight produces little change in velocity. Any thoughts on or experience with this extreme horizontal appreciated. Has anyone seen a node appear predictably between the horizontal extreme (presume extreme wind sensitivity as per Tony Boyer) and the presumptive powder plateau? More to follow.....and Yes, this is a factory savage palma off a gen 2 Sinclair. Thanks for any comments, Seymour Fish

 

[Bart B.]

The wind speed gets faster for every foot above the line of sight the bullet goes. How much depends on the terrain. If you make wind corrections for the wind in your line of sight, you might want to add up to 20% more for those winds aloft.

 

[seymour fish]

D Moran, no typo. 5 moa wide. waterline. Mystery. Thanks to all for comments

 

[seymour fish]

D Moran, Will discount #3, repeat test. Thank you again, Seymour

 

[22BRGUY]

seymour -

Accessing your test by vertical dispersion only (like true ladder tests are) and Inputting the Increment POI's as you reported them into a spreadsheet format (image below), by the Incremental vertical dispersions, show me relevant aspects:
A. #1, 2, 3 show no inherent accuracy to each other
B. #3 is a Scatter node
C. #4 to 7 yielded 8.5" of vertical dispersion from a 0.9-grain charge spread (.81-MOA, respectable)
D. #6 & 7 show a accuracy node with #5 in the mix (1/2-MOA or better potential)
From the performance of #5, 6, 7, and 7 being the highest charge tested, shows further potential to higher charges. It would be interesting to see how 2 more increments (42.6 & 42.9) might play out. Despite the mysteries #3, and not accessing any horizontal dispersion, the vertical dispersion of the increments show good directions to the top end of the ladder, and poor accuracy at the bottom - IMO

This is just plain awesome Donovan...Thanks much for the insight on my shooting as well.

 

[Alex Wheeler]

Do not be lured in by the charges that shot flat. Go to the powder node Donovan pointed out. I just had a strange ladder test result myself. Very good vertical out of the node and poor vertical in the node. Further testing showed that out of the node vertical did not stand up to larger groups. The key was to go to the node and work seating depth. That gave me the best results.

 

[seymour fish]

Donovan, Really appreciate your insights. Your graphical representation makes the data speak volumes. Will load higher in 0.3 gr increments and run them on same target, same DA (600'), same right to left condition as soon as it reappears. Meanwhile intend to reshoot a quick 100 yd ladder to include the higher charges, and to chrono this spectrum separately with magnetospeed. Will hold exactly same point of aim. Did not touch the knobs during initial test, and will not move them. action torque is holding proper. borescope shows no carbon ring, no firecracking, and faint copper, thus stable test bed. Back in the cave for now. Thanks Again......Zfast, thank you for your insights as well. Spot on. Seymour

 

[seymour fish]

Zfast, have played with seating depth in .005 increments from .005 off just kiss to .040 off, and found no consistent joy except at .005. It becomes clear that the load was a hair above a very low node, as was using the #1 starting load described here. Will follow your lead and tweak seating depth once boundaries of the node are defined. Thank you for your kind assistance. Seymour

 

[dkhunt14]

Didn't you try them in? Matt

 

[Alex Wheeler]

Didn't you try them in? Matt

Agreed, no reason not to go in. Once you are close start moving the bullet .002''. You miss a lot moving .005''

 

[seymour fish]

DKHunt14: No Sir, have not yet tried seating on into lands. Soon will. ZFast: Appreciate your suggestion of .002" changes and will do so as well. Donovan: I have been shooting 3 rounds starting with cold fouled barrel, driving down to target, marking, making the round trip in 10 min, thus barrel essentially back to baseline temp for the next three (60 deg F ambient). Have started low and gone up on charge each successive increment. all same POA, no holding off. Have attempted to run tests at roughly the same DA in mild enough wind to avoid generation of vortices. Like the one shot incremental ladder x 3, as have always done that at 100, and changed the format to 3-shot to improve shooting-to-driving ratio as much as anything, while perhaps gaining a simultaneous notion of grouping capability. Heading to the cave now to load. Thanks again to all for the sound advise. Seymour

 

[seymour fish]

Update: seating depth from .005 off to .005 into lands at fixed charge of 42.1 8208xbr went into same node with .003 AND .005 into being tightest groupings. One shot Audette ladder at .oo5 Off showed good node at 42.4-42.7 gr into same grouping as above, and a 'mini-node' at 43.3-43.6 gr, 21" above the previous poi, and the next increment up climbed yet another 10", thus on the upswing , and showed pressure.
further refining it, 42.1 .005 off went 1-1/2" 3-shot group, 42.1 gr .005 Into lands went 6" vertical spread, 42.7 .005 off went 2-3/4" vert x 6" horiz dispersion (slight change in mirage-- didn't hold for it, 43.45 .005 Off went 3-1/2" vert with no horizontal. Shootability was fine across all. No discernible recoil increase or bipod hop change. barrel goes to 11:45. DA fluctuated from 120 at start to max 400 with sun and thick soupy mirage for short while, then down to '0' for last series of 4 groups. 750 flag 8-12 mph mostly, rapid switches early from 3-9-3, then largely switchy tailwind 5-7 o'cl same speed. mirage strangely trustworthy when visible. Chrono data tomorrow, and a fresh tank of gas. suspect 42.1 .005 off is the 53 degree/ DA 120 load, mild enough throat should last, best guess 2760-2770 fps so 1300m or bity better at 1K. the 43.45 gr .005 Off is strangely tempting on increased speed but is narrow and 'false', and approaching hot (moreso come spring/summer). Any further thoughts appreciated. Is it time to learn to shoot ? thanks, Seymour

 

[Alex Wheeler]

Make sure the load repeats with 5 or 10 shot groups.

 

[seymour fish]

ZFast, Yes sir will do. Chrono for grins, and will run 20 to see if holds up. Need a spotter!!! else will shoot it blind holding same POA trying to pick a condition. Say, how fast is that Malibu? Seymour

 

[Alex Wheeler]

It ran 10.30-10.40 on gas with a 400 sbc before I sold it. ;D

 

[seymour fish]

ZFast, well-earned moniker ! roadraced a 347 stroker Tiger till I wrecked it (1970-2010) r.i.p. Seymour

 

[seymour fish]

Chrono: 43.45 2889/ es11 33" high at 100 yd.
42.7 2847/ es 18 exactly same elevation
42.1 2813/ es 5 dead center in the above node and difficult to measure, but looks like in the ones....Seymour

 

[seymour fish]

Donovan, Thank you, sir. Intend to do just that. Have plenty of same lot # components, and a decent scale. Have measured h2o capacity of fired unsized cases and matched them. Hawkeye just back from the factory: reveals zero firecracking in throat and beginning of rifling, so she is good to go. I'm so excited can barely stand it !!!! ROCK AND ROLL. Say, does anybody have a couple spare factory savage Palma barrels for sale or trade??? Thanks to all for your helpful tips and encouragement. Seymour