Ladder test analysis

[avetjx]

Hello. Did a 5 shot ladder test today with my 6.5 cr masterpiece prs rifle. This is the first ladder test that I've done. I've been reloading for about 6 years and all the rounds I built used the same brass, same primer, and all were seated at the same depth. I have two rcbs chargemaster lites that were my powder throwers and were calibrated before loading rounds. I recently bought a labradar chronograph that I used to track the rounds.

As you can see from the data, my fps variability was to my eyes unbelievably high. The only real variable was the temp of the barrel. I did rest the barrel between sets but not to cold. Looking for other people's experiences with ladder testing to see if what data I collected is even close to normal and either way, looking for recommendations of what I can do to bring standard deviation to a much smaller number. Any insights are appreciated. Thanks.

 

[phlegethon]

What are your results with that rifle and chronograph using commercial ammo? Those numbers are a little hard to believe and I think measurement errors would have to be considered.

 

[avetjx]

What are your results with that rifle and chronograph using commercial ammo? Those numbers are a little hard to believe and I think measurement errors would have to be considered.

Can't remember the last time outside of 22lr I've bought commercial ammo. Might have to pick some up as a baseline. factory ammo is soooo expensive

 

[Molon]

Your data is fubared. An extreme spread of 426 FPS? A standard deviation of 164.4 FPS? You would have to be one of the worst reloaders on the planet for that data to be valid. So either you are one of the worst reloaders on the planet, or your Labradar sux. (I'm betting it's the labradar, not you.) Beg, borrow or steal a different chronograph and repeat the same test.

 

[SicVic]

My first reaction was "jamming the lands"???

 

[Mauser06]

Something ain't right.


First group completely clean bore? I get some weird shots from a squeaking clean bore. But nothing THAT bad.

My bore does take a fair bit of shooting to settle down on the lab too...so that could explain your other bad groups. But not THAT many...


Something seems astray.


Give us details. Bore condition and age.

Jump to lands?

How many firings on the brass?

Brass prep process?

 

[918v]

I think you are not assembling cartridges correctly to have that kind of ES.

 

[spife7980]

Make sure you have the radar aimed right. If you’re shooting across the beam or outside of its line of sight then it’s not going to know how to interpret the readings it takes. You need to be shooting in line with it. And not have crap in the way to obstruct it’s readings either.

But if that’s not it… good lord.

What powder bullet and case?

And how did they group on target?

 

[ReaperDriver]

Also make sure you have the Lab radar settings correct. If the unit is not set with the default settings correctly, it could give you erroneous readings. Here's my setup to give you an idea of what it should look like. The "rifle" setting is particularly critical to get it to read correctly, but other ones are important as well. This is using the app on my Iphone. But you should be able to do all this directly on the unit.



If the LR is set correctly, the next thing I would check is your Chargemaster. I use a chargemaster and get excellent results. However, I did have one go bad and RCBS replaced it. Suggest you throw 10 charges and check them against another scale that you know works. If they all average out at least within about .2 grs or so, you should be GTG. To get the extreme variations that you're seeing (400 fps delta), you'd literall have to be a whole couple of grains off. I have a hard time believing the scale could be THAT far off.

I would say that even if you were the worst reloader on the planet and picked up shitty range brass, did zero brass prep, and loaded and shot it - I still think you'd be hard pressed to get that much variation. I suspect something in your reloading equipment set up is not right.

 

[Doom]

First thought is you need to give us bullet, powder, brass make, primer type, seating depth. Next, you mention 2 CM Lites, you should only use 1 for load development. The target should be used to see if the dispersion matches the chronograph data.

A quick description of your case prep would also be helpful.

To check your CM, throw a load say, 40 gr. Take the pan off and then weigh it again. Do this ten times. You shouldn't very from the mean by more than 0.1 grains.

As for the LabRadar, I wonder if its picking a up the shots at the same point,

 

[ReaperDriver]

A couple of more thoughts on the Labradar, As I'm beginning to think this is likely the source of your errors.....

Alignment of the LR is critical. Using the little V-notch on top, try to get it lined up both vertically as well as left and right. You don't want it pointed at the ground or up in space. Once I do the notch thingy, I then step back and look at the overall big picture...... Is the LR perpendicular to the barrel in both axises?

The other thing is placement WRT to the muzzle. If shooting unsuppressed, ideally the LR would be about 12" BEHIND the barrel (especially if shooting with a brake) and about 12-18 inches offet to one side or the other. And ideally the barrel is lined up down the middle of the LR (i.e. Height or up/down). Although I've found this last alignment aspect to be less critical. I've gotten good readings even with the muzzle down near the bottom of the unit.

Also, was anyone shooting near you when you were using the Lab Radar? If the benches are really close together, it's very possible it's picking up other people's shots.

If all of these things above are not set up correctly - it's very possible to get some crazy readings. In my early days of using it if I didn't have things set up just right - I might get a 5000 fps from a .308 or a 1950 fps from a hot .223 or something crazy like that.

 

[avetjx]

Thanks to all who have replied!! After reading the descriptions of the labradar placement and the need for that consistency, that has to be the reason for the spread in the data. I actually had to move to another bay at my range in the middle of testing because I was getting hit with hot brass from a hole in the netting and therefore had to move my chrono and I can guarantee that it was not in the same place as it was before. I had no idea it was that sensitive to placement. I am also shooting with a brake so I think I have to be much more careful with my placement. Lastly, the suggestion of only using one chargemaster for the ladder testing is a great idea. Will do that from now on. This was my first time using it so live and learn. Happy shooting.

 

[avetjx]

Make sure you have the radar aimed right. If you’re shooting across the beam or outside of its line of sight then it’s not going to know how to interpret the readings it takes. You need to be shooting in line with it. And not have crap in the way to obstruct it’s readings either.

But if that’s not it… good lord.

What powder bullet and case?

And how did they group on target?

shooting 1 moa at 100 and 200 yds

 

[Agent Entropy]

If there's a shooter in another lane close to me, my labradar will pick up extra shots, with similar variances like you see here.

Which is weird, because I use the recoil trigger.

 

[Doom]

Thanks to all who have replied!! After reading the descriptions of the labradar placement and the need for that consistency, that has to be the reason for the spread in the data. I actually had to move to another bay at my range in the middle of testing because I was getting hit with hot brass from a hole in the netting and therefore had to move my chrono and I can guarantee that it was not in the same place as it was before. I had no idea it was that sensitive to placement. I am also shooting with a brake so I think I have to be much more careful with my placement. Lastly, the suggestion of only using one chargemaster for the ladder testing is a great idea. Will do that from now on. This was my first time using it so live and learn. Happy shooting.

Make sure you let the CM warm up for at least 30 minutes before using and try to keep it in a temperature controlled area when in use. If not the zero will drift.

 

[avetjx]

Make sure you let the CM warm up for at least 30 minutes before using and try to keep it in a temperature controlled area when in use. If not the zero will drift.

thanks. my reloading bench is in my home office so the temp is good and I do let it warm up. generally recalibrate once in the middle of a session just to make sure.

 

[ReaperDriver]

Also, even though the CM is not quite as sensitive as some of the super accurate .01 scales, I still make sure there are no fans on or A/C vents blowing over the bench when I'm throwing powder. In addition, if you want to get super anal - you'd make sure you had a clean power line for the unit so you don't get any errors.

Having said all that, none of those things above would EVER account for a 400 fps velocity difference. It's not the scale, it's most likely the Labradar setup and environment.

 

[ReaperDriver]

I am also shooting with a brake so I think I have to be much more careful with my placement.

The Labradar isn't THAT sensitive to placement. You have a decent window to get it into as long as it's pointing at the target. That seems to be the most critical one. Also, with a Brake - you definitely want it well behind and off to the side of the muzzle about 12" or more. Shooting with a can is far more sensitive to placement.

 

[BuildingConceptsllc]

AC. Blowing on the chargemaster, even from a ceiling register that is 6 feet away will definitely make it drift. Not sure if fluorescent lights mess with it or not, but have seen the a.c. effect myself. Of course as said, that definitely isn't accountable for the massive flux here , its got to be bad LabRadar readings.

 

[avetjx]

at this point, bet my left pinky toe its the labradar. my reloading practices are pretty spot on, been doing it for a long time and ever since I got the CM's, my room fan has to be off when i'm dropping charges otherwise the scale will bounce all over the place.

 

[phlegethon]

I think you would not get velocity spreads that high even using a Lee dipper for your charges. I highly suspect it’s the LabRadar.