Chronograph numbers

[rclark]

At 100 yards, the time of flight is too short for gravity to act much on the bullet

I would add that it depends on 'velocity' (time to target). I wouldn't test my slow revolver cartridges out to 300 yards....

 

[hounddawg]

I have yet to find a load that groups tight at 100 but fails at 800. Powder charges I only do 3 round groups at 100, seating depth is tweaked at 300 where I do 2 to 7 round groups doing the adjusting at the range. It's my own method that I have developed over the years, works for me. I don't expect anyone else to use or approve it


edit-

On the 2 to 7 rounds. If the first two are a MOA apart the group will not get any smaller with three, four or give. If it can go seven rounds and stay around 1/2 MOA then it is good for twenty if I do my part. Why waste bullets and primers

 

[RC20]

I reload to shoot.

Maybe Tubbs can shoot good enough to do the data mining and come up with nuances.

The only thing I note (keep) is the Avg, what powder charge got me that average and was it a good group.

I just keep the LabRadar running all the time because its easy and I get an readout on the Average as the COAL is adjusted. But if the ES is wild and its still a good group? Yep I keep that load and see if it will duplicate.

 

[Unclenick]

It's dependent on barrel timing. The vertical dispersion seen as you step loads up in an Audette Ladder ceases and clusters at spots. Constantine attributed that to harmonic muzzle swing, while Milosovich attributed it to the velocity flat spots in a load string that today folks credit Scott Satterly with figuring out, though he was not yet part of the shooting scene when Milosovich wrote about it. The limitation of the ballistics programs is the one I mentioned in the last post. They assume a perfectly rigid gun. Real guns and riflemen aren't rigid so recoil moments and barrel bending get involved. Nonetheless, the fact even Creighton Audette could not see enough vertical displacement to make his ladder work at 100 yards, but could at 200, with Constantine liking 300 better, proves it is possible to group vertical stringing fairly well at 100 while not having it do well further out. But if your 100-yard load lands in the middle of the flat spot Audette was searching for in the first place, then it won't be an issue.

 

[stagpanther]

Unless it's a cartridge I never intend to shoot past 100 yds, I never test at that distance if I can help it. I didn't start out that way, but over the years I definitely experienced enough cartridges that grouped well at 100 mysteriously fly apart at 300 yds to push my ladder test distances out. I was never a believer in the "spin stabilization theory," at first, and maybe the greater distance just makes the deviations more obvious for my eyes. I generally don't look just for the magic minimum SD/ES--but the group that is bracketed on either side of the charge weight by very good group/numbers as well that used slightly higher/lower charge weights.

 

[hounddawg]

When a group falls apart at 300 - 1000 I have found it almost always has more to do with my shooting ability than the load. I also came to the conclusion that when a a slower shot hits higher on the paper than a faster shot it is becasue my POA was a tad higher.

My ego wants to believe I am a machine rest and my aim and technique are perfect shot after shot with god like wind reading ability, my common sense brings me back to reality.

here is a link to a video showing how simply changing the cant of the rifle 1° will change the POI 5 inches at 1000 yards

https://www.youtube.com/watch?v=DJTN82AYcqU

 

[Unclenick]

Lots to keep track of. No doubt shooting skills end up being the limiting factor when you get everything else right. Per the velocity factor, I've made the mistake a couple of times of letting a round cook in a warm chamber a little too long at 600 yards and getting a 12:00 9 from the extra velocity for my trouble. It's just another of the many variables.

Per my mention of Milosovich and Satterly, is nobody here using the chronograph to generate velocity ladders to look for flat spots?

 

[stagpanther]

is nobody here using the chronograph to generate velocity ladders to look for flat spots?

That's kinda sorta what I do, I find that adjacent charges (+/- .2 grs or so) that have very close to identical SD/ES will also be very close in velocities. Have you observed the same thing and if so do you think there is a correlation?

 

[hounddawg]

I used to use the Cortina 100 yard load development for just that Nick but when I started analyzing my development I discovered that my smallest groups almost always had the lowest chrono stats. I just do not feel the need to overcomplicate these days SO all I concentrate on is group height on the powder charge and overall group size when doing seating depth, it does not matter if it is at 100 yards or 800 yards.

The only numbers I sweat these days in load development is the 95% CEP which I want to be below .5 MOA. That way if my POA and wind reading is good I can pretty guarantee a 97% score. For that I use OnTarget software which at $35 is less than 100 bullets

here is a 10 shot practice target that has .4 MOA 95% CEP's, which are in the lower left corner of the box. I over compensated for the wind shifting from 3 o'clock when I did my sighters to 6 o'clock when I shot the group but I was pleased with the overall group size

Like I said earlier it works for me

 

[Unclenick]

The OnTarget TDS is good software. The ability to virtually overlap multiple targets increases your statistical certainty without making you shoot so many rounds into each group that you can't distinguish the individual holes any longer.

 

[hounddawg]

well my latest spurge is for a Shot Marker system so my load development may distances my evolve once again. Only thing that bothers me about that is I still do not trust my technique enough to be able to separate the wheat from the chaff. Like I said in a earlier post , my ego wants me to believe I am as accurate as a machine rest BR rig, but the reality is I am human with questionable technique and wind reading skills. I will probably stick with 100/300 for development purposes

The OnTarget TDS is good software. The ability to virtually overlap multiple targets increases your statistical certainty without making you shoot so many rounds into each group that you can't distinguish the individual holes any longer.

This is one of my first F class matches back in fall 2017. It took me until the third match to get my group centered. 189, 190, then a 194 @ 300. This is the composite is of all three targets and sixty rounds. I no longer archive all of my matches since we went to the Kongsberg Target Systems which does not export but I do archive all of my practice targets which my way of keeping a reloading log

 

[Unclenick]

That's a bummer about the Kongsberg not exporting. Doesn't it log data for the match director at least? I should think they'd want that in the off-chance of a record being set.

I almost pulled the trigger on the Shot Marker, too. Since you've already got one, I am interested to hear how it does. In particular, I am interested in its POI consistency. It says, in a typical frame, you get 2-3mm of possible error. It doesn't say if that is unilateral error or plus and minus error or if it is a fixed offset error or a varying error. If the latter, it's only good to a quarter of an inch at 100 yards, so I would consider it a 200 or 300-yard and beyond device and would still record paper at 100. If it's a fixed offset, then bullets going through the same hole at 100 will still be reported as such, even if the exact point of impact on the paper is off by an eighth of an inch (a big "so-what" situation for load development).

Anyway, I am looking forward to your evaluation and would be interested to learn how closely the tablet target image and the actual target compare.

 

[hounddawg]

That's a bummer about the Kongsberg not exporting. Doesn't it log data for the match director at least? I should think they'd want that in the off-chance of a record being set.

for the matches we have a second person recording the string, both the shooter and the recorder sign. What some do is take a phone pic of the tablet. No idea how it would work in a record situation

I almost pulled the trigger on the Shot Marker, too. Since you've already got one, I am interested to hear how it does. In particular, I am interested in its POI consistency. It says, in a typical frame, you get 2-3mm of possible error. It doesn't say if that is unilateral error or plus and minus error or if it is a fixed offset error or a varying error. If the latter, it's only good to a quarter of an inch at 100 yards, so I would consider it a 200 or 300-yard and beyond device and would still record paper at 100. If it's a fixed offset, then bullets going through the same hole at 100 will still be reported as such, even if the exact point of impact on the paper is off by an eighth of an inch (a big "so-what" situation for load development).

Anyway, I am looking forward to your evaluation and would be interested to learn how closely the tablet target image and the actual target compare

So far I have only calibrated my targets at 100 yards. I built two frames one for 100 and one for 200 - 1000. I bought a second set of mounts for the short range. I plan on using the load development targets on the small frame. Then bringing the paper back home to scan in for archiving in OnTarget. So far it seem to work fine I will be doing some300 - 500 yard practice with it this coming week.

The primary reason for buying one was for long range practice. Getting real time feed back for POI's for wind shifts, mirage etc. I will be using poster board or back of old targets with stick on dots for various group shooting exercises. F Class John has a lot of really good videos on the Shot Marker you may find interesting.

https://www.youtube.com/c/FClassJohn/videos

 

[Unclenick]

Thanks. I hadn't seen those.

Yes, the longer-range possibilities as a tool for helping refine wind reading skills is certainly one of the attractions of the system.

 

[hounddawg]

I figure that if I set up my phone to record me shooting and real time feed back on the POI I can analyze my technique and determine if it was me or the ammo that caused that flyer.

 

[Unclenick]

If you have remote wind speed measuring spread out over the range or else very steady wind condition, you can calculate where the bullet should have gone if you and the ammo were perfect and how far off the ammo would have to have been to cause equal displacement. If the latter is outside what you measured statistically for the ammo, it's pretty certain to be you that caused the issue. An interesting training setup, for sure.

 

[hounddawg]

If you have remote wind speed measuring spread out over the range or else very steady wind condition

nice theory or if you have no terrain features like the boys out west have but on my home range that will not ever happen. We get a lot of swirls and switches, I can put out flags and have all pointing in a different direction either at the same yardage for different benches or every 100 or so down the range. About all you can do is pick a condition, shoot your sighters and pray you get that condition often enough to get 20 rounds off. That is why I sometimes may seem dismissive of getting that extra .1 MOA at 100. Wind reading rules all in F class. One thing I am bad about is letting a round cook in the chamber while waiting on the condition change.

 

[RC20]

One comment on shooting distances. My preference is 200 yards, but the range that has that distance doubled its prices ($350 a year) and that was too much as its realistically 5 month of possible good shooting (amid all the other aspects of a busy Alaska summer). Ergo, I will take my 100 yards and Sr, discount and live with it.

I found a node that my 6.5 x 47 likes, so I loaded up a bunch of rounds and kept the Chrono ruining for 10 (it missed one, got 9 - downside to the shooting benches is you can't get the LabRadar as near the muzzle as it likes)

So, in 5 shots, the ES was 20, the SD was 9.9. 9 Shots, ES opened to 30, SD moved to 10.7.

First 5 were 1/4 inch group (got in the grove, the next 5 were a 1/2 inch group.

Me thinks the shooter not the rounds.

 

[RC20]

This is a good real world write up (my opinion) on the situation

https://www.gunsandammo.com/editori...-extreme-spread-and-standard-deviation/247510

The reality of what is good ES (and its associated SD) are nice as it lays out what is possible consistency wise. So basically if you have 50 FPS and under you are doing a good job. 35 FPS and its very good. 25 FPS and you get the Nobel Medal of consistency.

Not directly addressed is barrel harmonics and consistency of velocity that achieves that, but you can infer that 50 FPS ES gets you there.

So, 20 ES I had in my 1/4 group is really nice but invalid sample wise, 9 gets me a more realistic 30 FPS.

The days shooting range from ES 71 to 20. More around 35 fps average.

SD just falls in where it may, its going to be low below 35 FPS.

 

[RC20]

SD:

You have to go down a bit into the write-up , but this was the best explanation to me as it gets out of deep math and puts it in terms I can understand .

https://precisionrifleblog.com/2021...ive-fire-muzzle-velocity-consistency-summary/