My first chronograph experience [Archive] - Glock Talk

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racer11
08-04-2012, 14:03
As soon as the postman knocked on my door I read thru the instructions and set it up and went to shooting for some trial and error experience.

I first tried some 22s and compared rifle to pistol and noted the speed and the advertised speed on the ammo box, and the speed was really close.

I then tried some .40 reloads from my G23 and noticed some interesting difference in speed between the load and the speed listed in the Lyman book. One powder load resulted in much faster speed than what the book listed and one other load with different brand powder the bullet was slower than what the book said it should be running.

I had one 40 round register about 560 FPS and all the others were running around 875. As soon as the slower round registered I could tell the difference in physical feel,,,if it had not been for the numbers showing the difference I would not have noticed the light load.

I loaded up several rounds and added 2 grns or powder and I could see a difference,,,that was interesting !!,,, going by felt recoil I would have not known anything different.

I do have questions ,,, With my glock,,, what is the best distance from the unit for the best reading,,,or does distance make a difference.

And what about where the bullet goes thru the two Vs,,,the instructions says 4" is that right or best.??

I noticed every bullet varied in speed,,is that normal ?

Any tips or advice to send my way would be great !!

After using this chrono I can not see how anyone loads without one,,,,it is like driving a car with a speedometer.

F106 Fan
08-04-2012, 14:23
I then tried some .40 reloads from my G23 and noticed some interesting difference in speed between the load and the speed listed in the Lyman book. One powder load resulted in much faster speed than what the book listed and one other load with different brand powder the bullet was slower than what the book said it should be running.


I never get very close to what the book says.


I had one 40 round register about 560 FPS and all the others were running around 875.


Any chance you didn't put in enough powder?


I do have questions ,,, With my glock,,, what is the best distance from the unit for the best reading,,,or does distance make a difference.


Whatever the manufacturer says... For my CED M2, the recommended distance is 10 feet. I suppose with Blue Dot I might move it out a little :rofl: The point is to make sure that it is the bullet tripping the sensor, not the powder discharge.


And what about where the bullet goes thru the two Vs,,,the instructions says 4" is that right or best.??


Again, whatever the manufacturer says... This dimension is probably fairly critical. The sensor needs to really be able to see the glint. Of course, the 4" recommendation guarantees them the sale of replacement sensors from time to time. Or an entire unit, depending on construction.


I noticed every bullet varied in speed,,is that normal ?


Sure. A quality measure is Extreme Spread. The less, the better. Same with Standard Deviation. You want low numbers to have repeatable ballistics. This is a lot more important in precision rifle than it is for pistol game playing.


After using this chrono I can not see how anyone loads without one,,,,it is like driving a car with a speedometer.

It definitely tells you whether your loads are any good (repeatable) and eliminates all the BS from the manuals.

Richard

WiskyT
08-04-2012, 14:50
They all seem to recommend 10 feet, but IME, with the Chrony brand, 20 feet is better. When you are too close, you end up getting funky readings off of the muzzle blast. Use bamboo grill skewers to support the diffusers. If you hit one of those, nothing bad happens, you just have a broken skewer. With the metal rods that come with the units, they transmit force to the main unit and **** it up.

I always use a target for an aiming point. I set a target up without the chrono in place and mark an aiming point on it. I then shoot a group into the target. Then I position the chrono so that the group is in the sweet spot of the unit and fire all shots at the aiming point I marked out. This ensures that all bullets go into the target, and none go into the chrono. I put the chrono a couple of feet behind the chrono. I get little, if any, "errors" this way. If I put the target downrange, I get errors.

This is my set up. In the second picture, you can see the jagged hole that is the group all of my shots go in. This kind of accuracy is easy at 20 feet. Even if the group size were doubled, the chrono would still read fine.

http://i1228.photobucket.com/albums/ee460/Wiskyt/1025111500a.jpg

http://i1228.photobucket.com/albums/ee460/Wiskyt/1025111500.jpg

Taterhead
08-04-2012, 14:55
EDIT: Whisky posted prior to me finishing my post so I did not notice that he pretty much covered what I have to say...

F106 pretty well covered it.

Quick notes:

Farther from the chrony is better. Some powders like Blue Dot, as F106 stated, can interfere with chrony readings. If readings don't track with expectations, move back a few more feet. If you are really anal, you can "correct" the chrony readings to get a muzzle velocity. It is pretty insignificant, so I do not bother.

A lot of us have shot chronies and/or diffuser rods. One hint is to put a target behind the chrony so that you have a small point of aim. Some have replaced the metal diffuser rods with dowels or bamboo skewers. I wish I had when I shot my rods one time. Shook the chrony all to heck and dislodged all of the inards. I was getting ready to shoot another round when my buddy asked about my previous velocity. I sort of looked down at the chrony as I sent the round, and well, you shoot where you are looking. A quick disassemble and re-assemble and it works fine again. It would have been less dramatic if I had used wood rods.

Don't forget to disconnect the battery after each session, and keep a fresh one in your range bag. Mine doesn't at all like low batteries, and it sucks to drive out to the range and have low juice in the battery.

I agree that a chronograph is an essential companion for load development.

WiskyT
08-04-2012, 15:03
EDIT: Whisky posted prior to me finishing my post so I did not notice that he pretty much covered what I have to say...



Don't mind me, you just go right along posting like you are the only one who thinks if this stuff.




:supergrin:

Seriously, you remembered the part about the spare batteries. That's big.

F106 Fan
08-04-2012, 16:03
One thing that concerns me about getting farther away is with the OPs chrono, he has to stay within 4" of the sensor.

I would want to have a bench rest if I had to shoot that close. I certainly wouldn't do it off-hand. The slightest little flinch and the chrono sensors are toast.

I like the idea of shooting the target and THEN setting up the chronograph. Next time out that's how I will do it. Maybe I'll run a string from the top of the rest to the hole in the target and then assemble the sensors around the string.

I'm thinking about the problem of setting up during a cease file (or two). On the action pistol range where I 'own' the entire bay, it's no problem.

Richard

WiskyT
08-04-2012, 16:43
One thing that concerns me about getting farther away is with the OPs chrono, he has to stay within 4" of the sensor.

I would want to have a bench rest if I had to shoot that close. I certainly wouldn't do it off-hand. The slightest little flinch and the chrono sensors are toast.

I like the idea of shooting the target and THEN setting up the chronograph. Next time out that's how I will do it. Maybe I'll run a string from the top of the rest to the hole in the target and then assemble the sensors around the string.

I'm thinking about the problem of setting up during a cease file (or two). On the action pistol range where I 'own' the entire bay, it's no problem.

Richard

While you need to be a decent shot, you don't need to be Camp Perry material. 3" at 7 yards is good enough. I never really checked to see if my rounds are passing 4" over the unit. I could shoot higher and it still works, that much I do know.

When you shoot the target only set-up, you'll see how tight the groups are. You can shoot five, or five hundred rounds until you are comfortable with where your rounds are impacting.

The main thing, and i know this from personal experience, is to have an aiming point. Your eye stays on the front sight which is super-imposed over the aiming point. This stops you from letting your eye drift to the chrono. If your round hits the chrono, it's because your eye drifted to the chrono. The bullet goes where you aim.

This is basic precision marksmanship, but used at close range. It's what you've always done, but at such close range it is foolproof.

DoctaGlockta
08-04-2012, 16:54
I'm pretty sure if I had one of those I'd shoot it pretty quick.

fredj338
08-04-2012, 18:50
If it's a Chrony, the shots need to be dead center, no more than 6" high or you get errors.
You need to understand that book data & what the chrono tells you will ALWAYS very, always. Companies use dff test rigs, some like LYman, not even real guns. So add in diff components & conditions, you will always have diff readings.
It is completely normal for there to be a shot to shot variation. It's better if that spread is smaller, but it is always there. Again, variations form one case to the next & testing variables are always diff. Just don't get the idea that you keep putting powder in until you get the desired vel result. That can be disasterous for all the variables I listed.

norton
08-05-2012, 07:51
I place my chrony about 10 feet in front of the muzzle. If I get error readings, I move it back a bit. I like shooting under a canopy, and keeping the chrono close means I can keep it out or direct sunlight. IMO, start close, further away is a good way to get a fresh new hole in your electronics.

F106 Fan
08-05-2012, 08:36
Just don't get the idea that you keep putting powder in until you get the desired vel result. That can be disasterous for all the variables I listed.



Just thought I would emphasize this point. That a load doesn't produce the matching velocity is interesting but we can't let low velocity make us think that it is ok to pour in more powder.

If the velocity is insufficient, it is better to change powder.

Richard

racer11
08-05-2012, 08:44
Just thought I would emphasize this point. That a load doesn't produce the matching velocity is interesting but we can't let low velocity make us think that it is ok to pour in more powder.

If the velocity is insufficient, it is better to change powder.

Richard

Sounds like some good advice from experience,,,,But ! When or How is the determination made to change powder because the expected VL is not reached as opposed to adding a few more grains of powder.

racer11
08-05-2012, 08:49
I place my chrony about 10 feet in front of the muzzle. If I get error readings, I move it back a bit. I like shooting under a canopy, and keeping the chrono close means I can keep it out or direct sunlight. IMO, start close, further away is a good way to get a fresh new hole in your electronics.

So,,,any time the shooter is too close the ERROR msg will appear?
Reason I ask was yesterday I was shooting my G 40 and I was about 6 feet away and I never got a error msg.

I did have a problem with the sun causing some FPS readings to be radically slow. I just covered the unit up with a empty grain sack and the problem was solved.

WiskyT
08-05-2012, 08:55
So,,,any time the shooter is too close the ERROR msg will appear?
Reason I ask was yesterday I was shooting my G 40 and I was about 6 feet away and I never got a error msg.

I did have a problem with the sun causing some FPS readings to be radically slow. I just covered the unit up with a empty grain sack and the problem was solved.

Errors will be an obvious symptom, but false readings will also happen. 6 feet is too close. Shoot a target at 6 feet and see what you get, powder all over it. That same powder flying over your screens screws up your readings. Shoot at 20 feet and record the numbers. Move to 10 and then 5 and then 3 and see what happens. Your data will start getting screwed up when you get too close.

Different brands of chronos may be more tolerant of shooting at too close range and different loads and different calibers will give varried results. 22LR out of a 24" rifle may not be a problem at 5 feet, 357 mags with WW296 out of a 2.25" snubbie will definitely give you false readings.

fredj338
08-05-2012, 11:27
Sounds like some good advice from experience,,,,But ! When or How is the determination made to change powder because the expected VL is not reached as opposed to adding a few more grains of powder.

Never exceed max data. It is exactly th epoint I was making about understanding the test methods & that ALL guns will give diff readings. Trying to chase the vel readings in the manuals w/ a chronograph is only asking for trouble. Example:
A buddy of mine has his new chron out & testing 9mm loads. He is perpelxed why his ammo is shoiwn pressure signs & he isn't even close to the book vel. His test platform, a Kahr compact. You can not expect identical results using diff test platforms. He now understands what a chrono is for.
I agree w/ WT, shooting closer than 10ft is always going to cause more problems than not. The greater the muzzle blast the further you should be. I test handguns @ 12-15ft, rifles @ 20-25ft.

F106 Fan
08-05-2012, 12:20
The idea behind powder selection is first knowing what you want to achieve.

If you want light target loads with little recoil, you will probably want to use a fast powder. Fast powders don't usually result in high velocities.

If you want heavy self-defense loads, you will probably want to use a slower powder.

Look at the load data/velocity for various powders and correlate that with powder burn rate.

http://www.hodgdon.com/burn-rate.html

If your manual has loads for Longshot, they will very likely be the fastest of the bunch. Longshot is a very slow powder. It's #51 on the list.

700-X, Bullseye and Titegroup are very fast powders (#12-14) and are best used for light target loads.

WSF (#36) and Unique (#31) are highly regarded around here.

Unique, in one formulation or another, has been around for more than 100 years. There's gotta be a reason!

Interesting history:
http://www.castpics.net/subsite2/GeneralReference/L&R-Smokeless.pdf

Richard

F106 Fan
08-05-2012, 12:36
I suppose barrel length ought to enter into the powder selection process.

A very slow powder like Longshot will still be burning long after the bullet leaves a 2-1/2" barrel. This has always been a complaint with Blue Dot (#49). A terrific light show and night and a lot of extra noise night or day.

So, you have to balance what is desired against what is achievable.

Richard