Tricks for getting chrony readings?

[rkr]

I have a very powerful bigbore, it shoots 175 grainers from 1300 to 1800 fps ... or that's what my beta chrony says it does. I'm trying to test my .45 in my garage and thus I need to set up the chrony quite close to gun, about 2-3 feet away, and the air blast is seriously screwing up the readings. Are there any neat tricks I could use to get proper readings without installing a silencer? The chrony has small led lights over the sensor holes so I need to be able to aim the gun quite precisely over the sensors.

[Back_Roads]

 I run a Caldwell indoors with it the same distance, but never at that energy level  my bigger bores get tested outdoors, but I use this clamp on portable unit, it has survived many .50 cal. rounds.

[rkr]

I have one of those chinese chronos as well but it doesn't work any better, the big airblast keeps giving way too high readings. I should be shooting around 800 fps (barrel limited) with current tune so it's not that powerful, just blowing out a lot of air that confuses the chrony.

[PasadenaMike]

I have one of those chinese chronos as well but it doesn't work any better, the big airblast keeps giving way too high readings. I should be shooting around 800 fps (barrel limited) with current tune so it's not that powerful, just blowing out a lot of air that confuses the chrony.

Problem solved https://utahairguns.com/fx-pocket-chronograph/

[gendoc]

I have one of those chinese chronos as well but it doesn't work any better, the big airblast keeps giving way too high readings. I should be shooting around 800 fps (barrel limited) with current tune so it's not that powerful, just blowing out a lot of air that confuses the chrony.

Problem solved https://utahairguns.com/fx-pocket-chronograph/

what he said ...................^^^^^^^^^^^^^^^^

[PasadenaMike]

I have one of those chinese chronos as well but it doesn't work any better, the big airblast keeps giving way too high readings. I should be shooting around 800 fps (barrel limited) with current tune so it's not that powerful, just blowing out a lot of air that confuses the chrony.

Problem solved https://utahairguns.com/fx-pocket-chronograph/

what he said ...................^^^^^^^^^^^^^^^^

Pricey? A little bit. Worth it? Every penny.

[ballisticboy]

I personally would never dream of using a radar chrono indoors. Over the last 20 years or more, muzzle velocity radars have caused more problems on our trials than anything else. There are just too many things indoors which can give spurious signals and false readings, many of which you will be unaware of with only one unit operating for each shot. Even the professional instrumentation engineers were surprised at the differences in readings between multiple units when we insisted in having two radars for each shot.

To reduce the blast problem, I would suggest firing through a hole in a plate to strip most of the air away. Some will still follow the bullet and may still interfere with the chrono, but the amount of air will be reduced.

[PasadenaMike]

I like mine. I’m no rocket surgeon but I’ve tested in my work van, shop, outdoors in the sun, shade and everywhere,  garage (hoarder mode and cleaned out) kids play room, bathroom, bedroom. As long as the pellet trap is 3 feet away and the fx chronograph is placed correctly basically under the muzzle it gives consistent readings. Im not launching spaceships just reading pellet velocities. Works for me:) oh and it fits in my pocket.

[gendoc]

i also have used it and compared it to several others. it works and works well.
every now and then it does give a "no read" but thats just fine because i'm not testing
hole shots from pro-modified dragsters !

[starlingassassin]

I have one of those chinese chronos as well but it doesn't work any better, the big airblast keeps giving way too high readings. I should be shooting around 800 fps (barrel limited) with current tune so it's not that powerful, just blowing out a lot of air that confuses the chrony.

Problem solved https://utahairguns.com/fx-pocket-chronograph/

gotta heavily agree with that solution,
id be lost without mine lol

[rkr]

I personally would never dream of using a radar chrono indoors. Over the last 20 years or more, muzzle velocity radars have caused more problems on our trials than anything else. There are just too many things indoors which can give spurious signals and false readings, many of which you will be unaware of with only one unit operating for each shot. Even the professional instrumentation engineers were surprised at the differences in readings between multiple units when we insisted in having two radars for each shot.

To reduce the blast problem, I would suggest firing through a hole in a plate to strip most of the air away. Some will still follow the bullet and may still interfere with the chrono, but the amount of air will be reduced.

Aha, plexiglas with a hole would allow aiming and strip most of the blast away. Thanks Miles!

[sb327]

Just make sure that plexiglass is secured very well. You are essentially creating a very large muzzle brake which are designed to transfer all the energy of the blast into the barrel to reduce recoil, essentially giving the gun a jerk forward.

I would consider as small a piece as necessary to block the sensors.

Do you have a thread here on the build? Sounds like a fun one!

Dave

[rkr]

Just make sure that plexiglass is secured very well. You are essentially creating a very large muzzle brake which are designed to transfer all the energy of the blast into the barrel to reduce recoil, essentially giving the gun a jerk forward.

I would consider as small a piece as necessary to block the sensors.

Do you have a thread here on the build? Sounds like a fun one!

Dave

Good points Dave, thanks!

It's this X2 Sniper I'm working with https://www.gatewaytoairguns.org/GTA/index.php?topic=110075.0

I made a 2mm stem for the valve and it's getting crazy dwell and thus pushing out loads of air. It would be fun if I could get that valve to seal, I think I need to change the seat geometry or valve face to make it self centering as the next step. I'll update that thread when I get it sorted out.

[Tusker]

Mr. Seller,

How does the chronograph you linked working out for you? I'm happy to see you list that. I got one a couple of weeks ago and haven't been able to get out to the range to test it yet. Any tricks you apply to make it work best?

I got it off of Amazon for about $30 during Christmas, after reading this: 

https://hardairmagazine.com/reviews/doug-wall-tests-a-low-cost-chronograph-its-pretty-good/

I like his idea of placing a block so not to shoot off the led plus the shrink wrap on the u-bolt to save the barrel from scratches seems nice too. 👍

If you have the time and don't mind sharing, would love to know your experience with yours. I'm really hoping to be able to get out to the range sometime thjs month! 🤞🙏

*edited to add: for about $30 I'm pleasantly surprised how many good reviews it's getting,!*

[mackeral5]

Using Caldwell and Competition chronographs I never had any problems with muzzle blast causing errors, even when testing a 4500psi .457 extreme.  But I was always able to maintain at least 6-8 feet of distance from muzzle to chrony.   Any closer and the muzzle blast could make a mess of the chrony/light kit.

My biggest problem was wrecking my infrared light kit on multiple when testing various configurations of a balanced valve in a gun equipped with .300 porting, some of which resulted in machine-gunning tank dumps.  My lights still work, thankfully.  However they have been pieced back together multiple times. 

The idea of using some type of blast shield  sounds like a practical solution assuming you do not have enough room to create space between the muzzle and chrony.

[Back_Roads]

Mr. Seller,

How does the chronograph you linked working out for you? I'm happy to see you list that. I got one a couple of weeks ago and haven't been able to get out to the range to test it yet. Any tricks you apply to make it work best?

I got it off of Amazon for about $30 during Christmas, after reading this: 

https://hardairmagazine.com/reviews/doug-wall-tests-a-low-cost-chronograph-its-pretty-good/

I like his idea of placing a block so not to shoot off the led plus the shrink wrap on the u-bolt to save the barrel from scratches seems nice too. 👍

If you have the time and don't mind sharing, would love to know your experience with yours. I'm really hoping to be able to get out to the range sometime thjs month! 🤞🙏

*edited to add: for about $30 I'm pleasantly surprised how many good reviews it's getting,!*

 It has never missed a shot, and I have never shot it. Some guns I mount it upside down as not to block the open sights, other than that just be sure you have enough clearance over the sensors.

[Tusker]

Thank you both for the reply!

Glad to hear these are solid. Can't wait to test it out!

[Spacebus]

I have also been shopping for chronographs, but the Caldwell and other "established" brands have countless reviews of poor performance in bright or outdoor situations, and I only shoot outdoors. I had good success with a cheap clamp on unit, untill my big bore sent it flying off and breaking it. After attempting to solder things back together it worked well for a few weeks and stopped taking a charge. Should I try another $30 chronograph or save up my pennies for the FX radar unit?

[Thane]

Use the FX pocket chrono in my very crowded 3 car garage.

Check against 3 other optical units and the FX concurs, with fewer errors/missed shots.

Never used the lab radar unit, heard it can be very picky.

Magneto speed bayonet style may be a better fit for you.

[Spacebus]

Use the FX pocket chrono in my very crowded 3 car garage.

Check against 3 other optical units and the FX concurs, with fewer errors/missed shots.

Never used the lab radar unit, heard it can be very picky.

Magneto speed bayonet style may be a better fit for you.

I know someone with the Magnetospeed, but it appears to be very fiddly. The FX pocket radar is high on the list, even though it is spendy, I just wish it could do PB stuff too for the price.