FX Chronograph

[treebeard]

Hi
I am having problems getting consistent readings from my FX Chronograph that is fitted to the barrel of my HW95 .177, can anyone confirm if fitting to the barrel is reliable on a springer as all the info I have found online seems to show them fitted to PCP's and was wondering if the recall was affecting the radar image?

The tests have been carried out about 1.5 - 2m from the backstop up to now.

I seem to get od reading or no reading I have tried fitting near the muzzle and moving back 50mm or so to no effect.

I have it connected to an iphone. now waiting for more batteries before trying some further tests.

[angrybear]

As it works by the speed/delay of a radar return, how can it possibly work correctly fitted to a gun that recoils causing it to move

[treebeard]

As it works by the speed/delay of a radar return, how can it possibly work correctly fitted to a gun that recoils causing it to move

That was my thought?

[averageplinker]

Doesn't it use the radar to track the speed of the projectile rather than movement of the rifle?

Does it have to be attached to the barrel? Can it be used below the barrel? Does it need a longer pellet flight to register the speed?

Sorry for only adding questions rather than providing answers?

Rich.

[angrybear]

Doesn't it use the radar to track the speed of the projectile rather than movement of the rifle ? Rich.

Yes it does but it needs the unit to be stationary so the return delay time from several signals at pre-set intervals can give the velocity.
If the unit moves back & then forward again with the recoil, the signal delay will falsely increase as the unit goes back extending the nominal distance to the projectile,
then falsely decrease as it returns forwards fractionally decreasing the nominal distance to the projectile.

So the projectile will appear to start off faster than it is, then appear to slow before speeding up again, that's going to confuse the computer maths & give a false reading.

[bighit]

Jesim on here has used one on springers . he tells how he did it here

http://www.airgunbbs.com/showthread....-on-underlever

[averageplinker]

Yes it does but it needs the unit to be stationary so the return delay time from several signals at pre-set intervals can give the velocity.
If the unit moves back & then forward again with the recoil, the signal delay will falsely increase as the unit goes back extending the nominal distance to the projectile,
then falsely decrease as it returns forwards fractionally decreasing the nominal distance to the projectile.

So the projectile will appear to start off faster than it is, then appear to slow before speeding up again, that's going to confuse the computer maths & give a false reading.

Ah yes. I get it now, thanks.

I have seen them being used off the rifle, just below and back from the muzzle. So guess this is the solution for the OP (and maybe what is noted in the thread link above?).

Rich.

[Steyr]

I thoght the FX had a base srew fir tripos fitting.
Position has to be very exact seems to be the theme.
I doubt any chrono will work well fitted to a recoiling gun apart from the likes of the millenium ( I thinks thats its name) which is strapped to the barrells of centre fires....
The labradar stands alone and also use radar tech.

The big advantage as I see it is that radar can tell you speed down range not just at the barrel. You can move a conventional chrono forward but the risk of a miss or stray shot adds to the law of sod.

[Antoni]

As it works by the speed/delay of a radar return, how can it possibly work correctly fitted to a gun that recoils causing it to move

Maybe it deliberately delays the measurement of the doppler shift to allow the gun to (almost?) stop moving. I expect the designer of the FX would have considered this kind of potential error.

I bought a Combro years ago and worried about it moving on the barrel of my springer - that product has no choice except to time the passing of the pellet very close to the muzzle - at the time of high recoil I'd expect.

Recently bought an old Skan chrono, it agreed with my Combro closely enough for my needs. Then sold the Combro.

....Just ocurred to me! If the Combro did move on the barrel it wouldn't matter -it might even help! The Combro would slide on barrel against the rubber bands because the Combro has some mass and is not firmly attached. The barrel would move a little, but because of its (small) mass the Combro would stay nominally still, and time the pellet's movement irrespective of recoil of the barrel.

Fact is: The Combro and the FX are well respected. If they were poor designs they wouldn't be.

[treebeard]

I thoght the FX had a base srew fir tripos fitting.
Position has to be very exact seems to be the theme.
I doubt any chrono will work well fitted to a recoiling gun apart from the likes of the millenium ( I thinks thats its name) which is strapped to the barrells of centre fires....
The labradar stands alone and also use radar tech.

The big advantage as I see it is that radar can tell you speed down range not just at the barrel. You can move a conventional chrono forward but the risk of a miss or stray shot adds to the law of sod.

The mk2 doesn't have the tripod mount, it only has the barrel mount. I have made a support to fit into the shed doorway that will hold the FX and have a window for the mussel. This will give protection to the FX and allow the pellets to court in my pistol target catcher and allow use with rifles or pistols. Hopefully, test tomorrow.

Thanks for all of your comments

[Daryll]

The mk2 doesn't have the tripod mount, it only has the barrel mount....

Yes, I discovered that when i bought mine a few months ago... I did query it with the suppliers, and they checked with FX... only the barrel mount now, and you can't buy the tripod mount

( I'd watched a YT review of it before i bought it, and he mentioned that you got both mounts...)

I used mine mounted to the barrel of an Supersport, and a Hatsan 900, and got fairly consistant readings from both.

[angrybear]

Maybe it deliberately delays the measurement of the doppler shift to allow the gun to (almost?) stop moving. I expect the designer of the FX would have considered this kind of potential error.

I bought a Combro years ago and worried about it moving on the barrel of my springer - that product has no choice except to time the passing of the pellet very close to the muzzle - at the time of high recoil I'd expect.

Recently bought an old Skan chrono, it agreed with my Combro closely enough for my needs. Then sold the Combro.

....Just ocurred to me! If the Combro did move on the barrel it wouldn't matter -it might even help! The Combro would slide on barrel against the rubber bands because the Combro has some mass and is not firmly attached. The barrel would move a little, but because of its (small) mass the Combro would stay nominally still, and time the pellet's movement irrespective of recoil of the barrel.

Fact is: The Combro and the FX are well respected. If they were poor designs they wouldn't be.

Clearly you don't quite "get it"

The Combro has 2 sensors a fixed distance apart, it doesn't matter if it moves because the sensors remain a fixed distance apart & it's the time between the two

The FX as I understand it, is a single sensor that relies on reading the time it takes for signals to leave, hit the pellet in flight & return, to do that the unit must be stationary, It should NOT be attached to the gun, even a PCP has a very slight recoil so the result will not be totally accurate.
Either someone at FX has not thought things through or it doesn't work by radar.

[Antoni]

Clearly you don't quite "get it"

On the contrary, I think we are in violent agreement.

[Steyr]

No. Angry bear is right. The combro works as stated. The FX relies on a pulse and return which is why doppler radar is capable of reading speed at various distances.

Combro are generally not good on springers due to recoil and they are not designed for rim or centre fires.

If you want a potentially mor reliable solution then the LMBR range may be a better buy. It uses IR beams so is not so influenced like the sky screen types.

I dont feel the FX quiet has this nailed yet and if I bought doppler, it would be labradar as I shoot powder too.

[Antoni]

Steyr,

The final point I made was that put very simply, the Combro will stay still because it is not firmly attached to the rifle - it can slide along the barrel, and will slide along the barrel. More acurately, the barrel will slide under the Combro.

Just spoke to someone who'se got an FX, he says he uses it loosely attached with rubber bands also.

The Combro doesn't care what the rifle barrel is doing, it only cares abt the time it takes for the pellet to go through the two timing traps - and therefore will be accurate up to its specification. If it were firmly attached, the Combro would be moving back or forth due to recoil, and that would add or subtract from its result.

No doubt that is a simplification of real life but I stand by it!