velocity lower and wide spread

[Labrat198]

I copied some loads I shot last year and noticed I have much more variation in speeds and most where lower.

last year 5 shot group: 2338, 2345, 2341, 2343, 2334
last week 3 shot group: 2280, 2147, 2325

as far as I know, everything is the same. its even the same canister of powder. The only difference is last year I was using once fired brass and now I have 5 firings on them. It was also a windy day, so I guess the chronograph could have been shaking some, maybe???

Thoughts?

[1Shot]

Different day, different chrno set up or light conditions, different temperature, especially when using ball powders, will change things. Also you shot 3 shots and not 5. Just one shot out of three will skew your over all results much large than with one out of five. Comparing apples to apples gives better results than comparing apples to oranges so to speak.

[Labrat198]

I stopped at 3 because the velocities were so out of control. If it wasn't for the tight ES last year I would assume I was significantly over pressured now. 178 fps is way too large a swing in the same group for everything to be working like it should in my mind

For the record, I am using H335 with 123gr Match Monsters. specific load posted is 27.5 grains.

I did shoot some 10mm pistol loads I am working on over the chrono at the same and had no issues with weird results.

[Klem]

I stopped at 3 because the velocities were so out of control. If it wasn't for the tight ES last year I would assume I was significantly over pressured now. 178 fps is way too large a swing in the same group for everything to be working like it should in my mind

For the record, I am using H335 with 123gr Match Monsters. specific load posted is 27.5 grains.

I did shoot some 10mm pistol loads I am working on over the chrono at the same and had no issues with weird results.

Correct, something is wrong. 178fps is too much for temp differences, even in double-based powders. That is not a hot load so you could have kept shooting for more data. My money is on the Chronograph. What type is it and how did you secure it? Any other indicators like where the cases were being ejected?

If you are shooting over a Chrony then this is not unusual as optical chonographs are notorious for errors if your bullets don't go exactly over the sensor; or the angle of light is not right, or there are shadows from clouds; or the battery is low; or it is moving; or not fully open, or not exactly parallel to the barrel.

[Labrat198]

Correct, something is wrong. 178fps is too much for temp differences, even in double-based powders. That is not a hot load so you could have kept shooting for more data. My money is on the Chronograph. What type is it and how did you secure it? Any other indicators like where the cases were being ejected?

If you are shooting over a Chrony then this is not unusual as optical chonographs are notorious for errors if your bullets don't go exactly over the sensor; or the angle of light is not right, or there are shadows from clouds; or the battery is low; or it is moving; or not fully open, or not exactly parallel to the barrel.

I have a Caldwell optical chronograph that is attached to a tripod, no weights added or anything to hold it in place beyond that. The Caldwell app monitors the battery when its connected to my phone, but don't know how much I trust that feature.

I've had optical errors before, usually unbelievably high or low, but that did cross my mind. I did shoot 3 of my 27.7 and 27.9 which had a 153 fps and 97 fps spread respectively. I took my pistol out after that and was getting 50-60 fps at worse, which I attribute to not having the angle exactly the same each time. Having the rifle bagged up, I should be getting the same angle for each group I would think.

The brass is pretty beat up after 5 firings, but no fresh ejector or extractor markings. Primers looked good and recoil felt normal. I use a brass catcher so that I don't know. The brass is a bit of a mixed bag of what I collected shooting factory at first.

[Klem]

Sounds like the chronograph wasn't working reliably on that day.

When using a Chrony I prefer to use it at night with LED strips on the underside of the skyscreens - eliminates the vagaries of daylight. Much more reliable.

I also shoot one of two ways to make it more stable;
1. Secure the chrono to a concrete block/breeze block with a mini tie-down strap. Put this on the ground and shoot prone - very stable and safe. Or,

2. On top of a concrete shooting bench and shoot from behind the bench with the gun on a tripod. So the chrono is on the bench and the gun on the tripod, not the other way round. Depends of course if the range rules allow this.

I also bought a few silicone rubber feet which come with a peel off sticky side. A few cents at the hardware store. Stick one at the corners and it's even more stable on a concrete bench (on one half only for a folding Chrony).

Plus a cheap spirit level/bubble to make sure it's level to the ground before shooting. A few degrees different to the line of bullet and this lengthens the distance of bullet path between sensors. Gives false lower readings.

12V Light strip and bubble level (EBay).
[ATTACH=CONFIG]16091[/ATTACH]

Rubber feet
[ATTACH=CONFIG]16092[/ATTACH]

Save yourself the angst and invest a few more dollars in getting your chrono more reliable.

To be honest, I use a LabRadar now, but still have the old optical chrony as a backup.

[grayfox]

Lab radar, or magnetospeed (I use the mgspd).

[Labrat198]

Well sounds like getting a mini howa just got bumped down the list.

Until then, tossing in a new battery and rigging something with some led lights are things I can do right now. Unfortunately night shooting isn't on the table

[FRB6.5]

If you are not shooting at a public range it might be possible to make a box or "tunnel" to place your chrono and lights inside to minimize sun angle and cloud variables. If you search you'll see some rather elaborate setups used with the very long Oehler screens. As Klem suggested going prone for something like this would be best.

Edit:
Some good chrono tips and a picture of what was referred to as a "coffin" at the bottom.
https://precisionrifleblog.com/2012/07/2...liability/

[Mad Charlie]

I have used white light diffuser panels for drop ceilings on the top and sides of my Pro Chrono. It seems to work, but not if there is much of a breeze, kind of blows, over.

[maxxmojo]

Back when I used my Caldwell chrono I found I had to use the LED strips all the time, even during the day, to get consistent readings from it.

[grayfox]

magnetospeed guys, magnetospeed....
step up to the 21st century lol!!
I think they're on sale right now btw.

[A5BLASTER]

magnetospeed guys, magnetospeed....
step up to the 21st century lol!!
I think they're on sale right now btw.

^^What he said^^

The benefits of the magneto speed far out way the cost difference between it and the screen type chongraphs.

I started with the tricked out Caldwell unit, it was nice, worked ok, was a plan to transport and set up/take down, had to pick and choose when and where I used it.

Magneto speed, I keep it in a range bag, quick and simple to use and not effected by light or weather conditions. Keep a extra battery with you and it's almost dummy proof.

[Labrat198]

The V3 is slightly more budget friendly. Looks like it would work with my pistols too, as long is I have a rail to attach it to.

[Rosecrans1]

I bought my Magnetospeed to replace my old Chrony and just shake my head for not switching years earlier. Very consistent output that I don't have to question anymore.

[Klem]

OK, before we get a skewed impression of opinions on chronographs let me add a balancing voice.

I can set my Labradar up in less than a minute and shoot for groups at the same time I record their velocity - without fear anything hanging off the barrel is going to influence the POI.

[Mad Charlie]

OK, before we get a skewed impression of opinions on chronographs let me add a balancing voice.

I can set my Labradar up in less than a minute and shoot for groups at the same time I record their velocity - without fear anything hanging off the barrel is going to influence the POI.

Which is why I use it. I set mine up with an inexpensive red dot to aim it with. Took a little fooling around to get it right, but now it's pretty quick. I also have a very bright green laser, might do some experimenting with that too, just because.

Some folks use scopes on them

[Labrat198]

Which is why I use it. I set mine up with an inexpensive red dot to aim it with. Took a little fooling around to get it right, but now it's pretty quick. I also have a very bright green laser, might do some experimenting with that too, just because.

Some folks use scopes on them

When you say, "get it right", what do you mean?

[jmkhenka]

OK, before we get a skewed impression of opinions on chronographs let me add a balancing voice.

I can set my Labradar up in less than a minute and shoot for groups at the same time I record their velocity - without fear anything hanging off the barrel is going to influence the POI.

Labradar is nice, but it has caveats just like the magnetospeed.
Twice the price (atleast here), and you might need some accessories like external microphone and tripod.

also appears to be unreliable with supressors. Other then that its nice.

dont get why people focus on the POI shift with magnetospeed. Depending on barrel, 3-10cm at most (well my friends 6.5x55 sporter Carl gustav had a 1 meter poi shift).
atleast for me its marginal, as the group shooting and speed testing is seperate affairs most of the time.

[Mad Charlie]

When you say, "get it right", what do you mean?

Sighted on target.