The guys I know who reload consider them an absolute necessity. And, when loading steel shot loads for waterfowling, or even lead shotgun loads, they separate loading manual fiction from real world fact. I have found steel shot loads running as much as 250 fps. slower than published data said they would. And, factory loads were often nearly that far off ....... normally slow. I wouldn't know that without the chronograph and would still be wondering why my steel shells were so ineffective.
Shooting Chrony?? Are they worth it?
- Thread starter M70
- Start date
striker
New member
It sounds as if the general consensus is that a chrony will tell you that your bullets especially in hand loaded cartridges, are shooting 200 fps slower give or take than the reloading manuals state. crap, this is depressing! How is it that the reloading manuals are so far off. One possible reason is the length of the test barrels used to formulate this data and the length of the barrel on your rifle. Remington in their rifle brochure gives a table that goes as follows.
Approximate change in muzzle velocity per 1 inch change in barrel
2000 - 2500 fps..........10 fps
2500 - 3000 fps..........20 fps
3000 - 3500 fps..........30 fps
3500 - 4000 fps..........40 fps
So if you look at the test length barrel and it is 24 inches and then you look at your barrel and it is say 22inches. Then you estimate how quickly your bullet is shooting and use the table to figure your new estimated speed.
Example.
7mm Remington Magnum 150 Grain at 3110 fps with a 26 inch test barrel.
You look at your rifle and find that it has a 24 inch barrel the difference here being two inches in barrel length.
then look at the table to see that your bullet fits into th e 3000 - 3500 fps range and this gives a difference of 30 fps per inch therefore you need to subtract (30 x 2 = 60) 60 fps from the manufacturers claim of 3110 fps giving you an actual 3050 fps.
This is all fine and dandy, but if the manufacturer is incorrect to begin with then the chrony would be super nice.
However who is to say that the chrony is accurate in its readings though? Is there any way to calibrate or test them? Does muzzle blast have anything to do with it? If this is the truth then the chrony must be set out at a distance in which the muzzle blast is not going to affect it. This then poses another question. If speeds listed in the reloading manuals is at muzzle and the chrony is set out at say 20 feet to compensate for muzzle blast then isn't a decrease of speed to be expected? According to the Barnes reloading manual a 7 mag bullet will decrease in speed 213 fps by the time it hits 100 yards with a 140 grain hpbt.
Approximate change in muzzle velocity per 1 inch change in barrel
2000 - 2500 fps..........10 fps
2500 - 3000 fps..........20 fps
3000 - 3500 fps..........30 fps
3500 - 4000 fps..........40 fps
So if you look at the test length barrel and it is 24 inches and then you look at your barrel and it is say 22inches. Then you estimate how quickly your bullet is shooting and use the table to figure your new estimated speed.
Example.
7mm Remington Magnum 150 Grain at 3110 fps with a 26 inch test barrel.
You look at your rifle and find that it has a 24 inch barrel the difference here being two inches in barrel length.
then look at the table to see that your bullet fits into th e 3000 - 3500 fps range and this gives a difference of 30 fps per inch therefore you need to subtract (30 x 2 = 60) 60 fps from the manufacturers claim of 3110 fps giving you an actual 3050 fps.
This is all fine and dandy, but if the manufacturer is incorrect to begin with then the chrony would be super nice.
However who is to say that the chrony is accurate in its readings though? Is there any way to calibrate or test them? Does muzzle blast have anything to do with it? If this is the truth then the chrony must be set out at a distance in which the muzzle blast is not going to affect it. This then poses another question. If speeds listed in the reloading manuals is at muzzle and the chrony is set out at say 20 feet to compensate for muzzle blast then isn't a decrease of speed to be expected? According to the Barnes reloading manual a 7 mag bullet will decrease in speed 213 fps by the time it hits 100 yards with a 140 grain hpbt.
Aside from relying on the calibration from the factory, you can buy yourself a box of high quality .22 rimfire match ammo and use that to check the calibration. It won't be exact, but it will let you know if there have been any changes which put the Chrony out of calibration.
I set my Chrony up 3 feet from the muzzle for testing shotgun loads. Most of the better ammo comes in pretty close to published velocities, taking into consideration the shorter barrel that I use.
I have tested RSI 99, which is a 1 1/2 oz. steel load. It was first developed using Winchester primers, the variety in the old white boxes. When the blue box Winchester primers were sold, no mention was made of any changes, yet, the velocities with the slower burn rate powders dropped way down when using the blue box primers. Winchester never admitted making any changes, but one tester has found a recent batch of blue box primers to produce very similar pressures and velocities as did the old white box version ..... contrary to what he observed with the former batches of blue box primers.
With out a chronograph, I wouldn't have known that I was getting only 1350 fps, using the blue box Winchester primers, rather than the 1550 fps., that the manual had stated, when tested with the original white box primers.
I set my Chrony up 3 feet from the muzzle for testing shotgun loads. Most of the better ammo comes in pretty close to published velocities, taking into consideration the shorter barrel that I use.
I have tested RSI 99, which is a 1 1/2 oz. steel load. It was first developed using Winchester primers, the variety in the old white boxes. When the blue box Winchester primers were sold, no mention was made of any changes, yet, the velocities with the slower burn rate powders dropped way down when using the blue box primers. Winchester never admitted making any changes, but one tester has found a recent batch of blue box primers to produce very similar pressures and velocities as did the old white box version ..... contrary to what he observed with the former batches of blue box primers.
With out a chronograph, I wouldn't have known that I was getting only 1350 fps, using the blue box Winchester primers, rather than the 1550 fps., that the manual had stated, when tested with the original white box primers.
Arizonahunter
New member
Quote:
Quote:
Oh, the F-1 puts the digital read out on the table with you, so you can't shoot it.
The F-1 Master has a remote display, the F-1 doesn't, but you can still shoot the chrony itself!! /ubbthreads/images/graemlins/smiliesmack.gif
MASTER CHRONY MODELS have the same features as their respective SHOOTING CHRONY MODELS plus: Remote Control with close-up read-out and 18 ft cord.
http://shootingchrony.com/products_SCMMCM.htm [/q
uote]
I stand corrected. Just looked at the box my unit came in and it is indeed a Master F-1.
Sometimes on very sunny days I put cardboard on the side most towards the sun. Otherwise I may not get a reading OR an extremely high reading. Also, I make sure to set it about 12' from the muzzle-further if you have a muzzle break.
All in all I would buy it again.
Quote:
Oh, the F-1 puts the digital read out on the table with you, so you can't shoot it.
The F-1 Master has a remote display, the F-1 doesn't, but you can still shoot the chrony itself!! /ubbthreads/images/graemlins/smiliesmack.gif
MASTER CHRONY MODELS have the same features as their respective SHOOTING CHRONY MODELS plus: Remote Control with close-up read-out and 18 ft cord.
http://shootingchrony.com/products_SCMMCM.htm [/q
uote]
I stand corrected. Just looked at the box my unit came in and it is indeed a Master F-1.
Sometimes on very sunny days I put cardboard on the side most towards the sun. Otherwise I may not get a reading OR an extremely high reading. Also, I make sure to set it about 12' from the muzzle-further if you have a muzzle break.
All in all I would buy it again.
NM Leon
New member
The factory data is from their particular test barrel. It will surely be within SAAMI specs, but that allows a fair amount of leeway. Who knows what the actual specs of their barrel are, how much wear, how much leade, what the actual dimensions of the chamber and bore are, etc., and who knows what the actual specs of your barrel are (or how they compare to the test barrel).
The change in velocity per inch of barrel figures are very approximate, and in fact the actual change will depend on the type and caliber of bullet, the dimensions and condition of the bore, the type of powder used, etc.
Chrony accuracy can be affected by all you pointed out Striker and more besides (angle of sunlight, etc). Some of it (distance from muzzle for instance) is easily accounted for by simple math, and (most of) the rest will give error factors that are so screwy that it's obviously error.
There will be some error in any machine, but I would imagine that (discounting the factors above) the error will be in feet, not hundreds of feet. In any case the error should remain consistant. If you have an inaccurate tape measure that says one object is 12" and another is 11", the actual measurements may be 12.015" and 11.013", but the "12 inch" object is still absolutely longer than the "11 inch" regardless of any error in the tape's calibration.
The change in velocity per inch of barrel figures are very approximate, and in fact the actual change will depend on the type and caliber of bullet, the dimensions and condition of the bore, the type of powder used, etc.
Chrony accuracy can be affected by all you pointed out Striker and more besides (angle of sunlight, etc). Some of it (distance from muzzle for instance) is easily accounted for by simple math, and (most of) the rest will give error factors that are so screwy that it's obviously error.
There will be some error in any machine, but I would imagine that (discounting the factors above) the error will be in feet, not hundreds of feet. In any case the error should remain consistant. If you have an inaccurate tape measure that says one object is 12" and another is 11", the actual measurements may be 12.015" and 11.013", but the "12 inch" object is still absolutely longer than the "11 inch" regardless of any error in the tape's calibration.
striker
New member
NMLEON
I see your point. I think in some cases there are so many variables to consider it becomes almost impossible to know anything for sure. I would like to get a chronograph for the mere capacity of knowing long range trajectories. I figure that I will be let down on the actual speed of my bullets. However knowing what my bullets are going to do at 400 and 500 yds when I have a 200 yard zero is well worth it. I always wondered if these reloading manuals weren't a bit inflated in the velocity dept. Knowing that others have had good luck and find chronographs to be very useful should be a clear indication for action.
I see your point. I think in some cases there are so many variables to consider it becomes almost impossible to know anything for sure. I would like to get a chronograph for the mere capacity of knowing long range trajectories. I figure that I will be let down on the actual speed of my bullets. However knowing what my bullets are going to do at 400 and 500 yds when I have a 200 yard zero is well worth it. I always wondered if these reloading manuals weren't a bit inflated in the velocity dept. Knowing that others have had good luck and find chronographs to be very useful should be a clear indication for action.
NM Leon
New member
You can get pretty close to knowing what's going to happen at 4-500 yds by knowing the MV (chrony) and using a ballistic program, BUT (and it's a huge "BUT"), the trajectory will depend on the BC and even when the BC that the manufacturer uses isn't inflated, BC changes with velocity. That means the more the bullet slows down the more the BC has changed and the further off of the predicted trajectory the real bullet will be.
Chronys, ballistic programs, etc, are great tools, and can save you a LOT of time and ammo, but the final test has to be real world testing at the range you are interested in.
Chronys, ballistic programs, etc, are great tools, and can save you a LOT of time and ammo, but the final test has to be real world testing at the range you are interested in.
Linefinder
New member
nmleon's observations are 100% spot on. Even knowing the exact MV of your load, and keying in the published BC into your favorite external ballistic software program will get you only so close to real world results.
While I've had some drop-charts/comeups tables come out pretty close to the real world, I've not ever had one that was exact. I've had some that were off by over a MOA at 300 yards.
BC's aren't exact, nor constant. Unfortunately, there's nothing yet that replaces actually firing at distance, if your range is long and the target small.
FWIW, I've found the biggest deviation regarding drop charts/comeups tables occurs with mild (slow)to mid-level loads. The faster you push the projectile, it seems, the closer it usually comes to matching the predicted drop.
The reason is obvious, when you think about it, but unfortunately, I didn't think about it for a long time.
/ubbthreads/images/graemlins/grinning-smiley-006.gif
Mike
While I've had some drop-charts/comeups tables come out pretty close to the real world, I've not ever had one that was exact. I've had some that were off by over a MOA at 300 yards.
BC's aren't exact, nor constant. Unfortunately, there's nothing yet that replaces actually firing at distance, if your range is long and the target small.
FWIW, I've found the biggest deviation regarding drop charts/comeups tables occurs with mild (slow)to mid-level loads. The faster you push the projectile, it seems, the closer it usually comes to matching the predicted drop.
The reason is obvious, when you think about it, but unfortunately, I didn't think about it for a long time.
/ubbthreads/images/graemlins/grinning-smiley-006.gif
Mike
Jack Roberts
Moderator - Deceased
The secret to making ballistics programs very accurate is to not use the default settings. If you plug in the actuall:
altitude, temperature, barometric pressure, humidity, scope height, etc. It will be spot on. I have never seen one that was even 1 MOA off at 1000 yards in the 20 years I have been using them.
Jack
altitude, temperature, barometric pressure, humidity, scope height, etc. It will be spot on. I have never seen one that was even 1 MOA off at 1000 yards in the 20 years I have been using them.
Jack
oldmuleskinner
New member
It is not just great for working up and testing rifle loads, but they work great all the way down to the low velocities of hunting arrows in the 200-300 fps range.
Linefinder
New member
Jack,
What I'll usually do when I have a load not doing what it's projected to do is tweak the BC. Normally, I have to tweak them down. Usually by playing with the BC, I end up with a pretty accurate comeups table.
I have several external ballistics programs, and my favorite is Oehler's Ballistic Explorer. It's a pretty easy program to tweak.
Mike
What I'll usually do when I have a load not doing what it's projected to do is tweak the BC. Normally, I have to tweak them down. Usually by playing with the BC, I end up with a pretty accurate comeups table.
I have several external ballistics programs, and my favorite is Oehler's Ballistic Explorer. It's a pretty easy program to tweak.
Mike
steve garrett
Active member
Quote:
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Here's the one I use. I bought it a Cabela's for a hundred bucks and it's one of the best load development tools I've had. This is a reading from a factory Remington 300 Ultra-mag shooting 180 grain bullets.
I broke this one. Had a gas check separate from a cast 44 mag bullet and hit the screen. I sent it back to the factory and they fixed it for free and didn't even charge me shipping costs.
Check out the backtalk (Product reviews with each product)section on Midway on the Chrony's, it's a pretty good insight into which chrono works well and which don't.
I got the same one Bob has and really like it. They are definitely worth it.
this is the unit to get, the shooting chrony sucks, the one I had would not work for me unless the light was just right, which was seldom, much much better useing the comp electronics unit
Quote:
Here's the one I use. I bought it a Cabela's for a hundred bucks and it's one of the best load development tools I've had. This is a reading from a factory Remington 300 Ultra-mag shooting 180 grain bullets.
I broke this one. Had a gas check separate from a cast 44 mag bullet and hit the screen. I sent it back to the factory and they fixed it for free and didn't even charge me shipping costs.
Check out the backtalk (Product reviews with each product)section on Midway on the Chrony's, it's a pretty good insight into which chrono works well and which don't.
I got the same one Bob has and really like it. They are definitely worth it.
this is the unit to get, the shooting chrony sucks, the one I had would not work for me unless the light was just right, which was seldom, much much better useing the comp electronics unit