Chronograph attachment

[JoeInTucson]

I have pretty much settled on the Garmin chronograph. But I was surfing the web and came upon an attachment to connect the chronograph to a rifle. Why would someone want to do this? I am sure there is a reason.

 

[Ranger188]

Not a good one.

 

[Varminterror]

King of 2 Miles competition requires anything used on the line to be mounted to the rifle. That’s one reason.

Capturing data during and despite dynamic movement of the rifle. That’s another reason.

Easier transport of the chronograph with the rifle and facilitated deployment of the chronograph in uneven terrain or among other inhibitory conditions which preclude use of the tripod. Yet another reason.

Mounting to the rifle precludes the chronograph from being knocked over by brake blast. Another reason.

Not all shots are taken from prone or a bench where the mini tripod could make sense.

 

[Varminterror]

Of note, the chronographs will read faster muzzle velocities - slightly so - when mounted to the rifle than when placed on a static mount beside the rifle.

 

[BuffaloBill]

And the recoil this subjects the electronics to may not be within a mfg’s warranty jargon. But modern circuit boards can take quite a bit of G punishment.

Edit to add: A mounting method having some “give” would be best. Some rubber or soft plastic would reduce the peak G considerably.

 

[big5ifty]

I know that for ELR, some shooters want to know the velocity of every shot, so they mount the unit to the picattiny rail for convenience.

I personally don't see the value in it. I won't shoot any better knowing the last shot velocity.

 

[Varminterror]

I know that for ELR, some shooters want to know the velocity of every shot, so they mount the unit to the picattiny rail for convenience.

I personally don't see the value in it. I won't shoot any better knowing the last shot velocity.

You will when you're making corrections to make impacts within 3-5 shots, and you see a shot sail high or fall short, and can gain confidence in your next correction by looking at your on-line or on-rifle chronograph to recognize that the shot velocity was on-average or high or low.

Example: my 375CT is tracking 3073fps average with 5-7fps SD and +/-12-20fps ES, and I sail a shot just over the top of a 2203yrd target with 19.7mils do I make a -.4mil correction on a .5mil tall target or send the same elevation? If I don't have the chronograph running and I can't tell that shot was 3090fps, which only needed 19.3mils to impact, and instead I take -.4 off and send 19.3mils for the next shot, and that next shot leaves the station at 3065fps, needing 19.8mils, I end up 1/4mil off of the bottom of the plate...

Instead, if I look up and see that first shot left the rifle at 3090fps, I know the +.4mil high sail was influenced by high velocity, so I have confidence to send the same hold on the next shot, expecting a slower velocity, closer to my Average, and I do NOT dial down the -.4mils, so that next shot at 3065fps, which needs 19.8mils, and I stick with my original call of 19.7mils, I'm low on target, not off of the plate.

So that's why I use my chronograph on the line. If we don't measure it, we can't manage it. Not to mention, getting more and more data to analyze my load is nice, since it's about $7 in cost every time I pull the trigger.

A mounting method having some “give” would be best. Some rubber or soft plastic would reduce the peak G considerably.

There's a 3D printed mount out there which has a spring-loaded pin-hinge (I forget who makes it), but I've only handled one once. Enough of us are shooting them on rigid ARCA rail mounts to have high confidence that the Garmin and the LabRadar LX survive while rifle mounted - and I've shot a few hundred rounds already with the Athlon mounted as well.

Personally, I think it works itself out pretty organically - most target rifles are heavy, especially ELR rifles, so the relative G forces in recoil are quite low. Most folks aren't doing a lot of shooting with hunting rifles, or tracking velocity as closely as we might with target/competition rifles, so the number of shots under this higher G-force scenario is lower. But I've mounted my Garmin several times on an 8lb 300WM hunting rifle and it hasn't spit the bit yet. Thousands of rounds on PRS and ELR rifles, a few hundred rounds on my hunting rifles, still kicking.

 

[big5ifty]

I understand the why, and mathematically it makes sense.

Shot to shot to shot velocity readings are good for determining the velocity increment as the day wears on and it heats up, you can then make a call as to when you change your ballistic calculator input for the higher reading.

On the line, shot to shot correction is a good way to keep missing. Rather confirm the flight of two shots before correcting, but the two must go in exactly the same place. If they don't go to the same place, you need to keep to the original point of aim, because if the ammo is right and the wind reading is right, there is just a small problem occurring between the trigger and the shooting mat.

I was shooting at a 1000 meter gong shoot, and there was a youngster on the line next to me, youngster meaning the rifle was almost as long as he was. His father was giving him dial adjustment shot to shot. The ammo was good, the rifle was good, the dope was good, the boy could shoot, but he kept hitting one, then missing, adjusting, and missing again. At that point, we were about halfway through the match, and his hit rate was very low. I asked him to stop making adjustments, and keep a constant aim point. I explained to him the concept of shot dispersion. He finished the match with a higher score than his father.

 

[Varminterror]

On the line, shot to shot correction is[...]

...how guys winning ELR matches are winning them.

But there's a difference between how 1000yrd matches are shot and ELR matches are shot.

Critically, knowing whether a miss is due to velocity or due to wind lift/downdraft or random dispersion within the potential group is how the shooter can make educated corrections, instead of blind corrections.

Missing twice because you ignore the splash and don't know whether to make a correction or send the same isn't a good match strategy for ELR matches - especially at Multiplier scored matches, or hit to advance matches with only 3 opportunities per target.

 

[big5ifty]

Critically, knowing whether a miss is due to velocity or due to wind lift/downdraft or...

Knowing the velocity of the last shot has nothing to do with wind. You can't see a up / downdraft. The wind factor at range affects the bullet much more than a few fps of up or down velocity difference.

Missing twice because you ignore the splash..

Why would you ignore the splash ? Unless you and the spotter didn't see it ?

If you've shot an ELR match, you fully understand that without the splash, you're shooting blind.

...how guys winning ELR matches are winning them.

This implies that every ELR match winner is running a chrony. They are not.

 

[Varminterror]

It doesn’t take much more than common sense to realize that I did NOT imply every ELR match winner always uses a chronograph… but… I can state and demonstrate that highly successful ELR shooters do and ARE using chronographs on the line.

Here are some of the most productive folks in the game, like Jeff Medlin with his mounted at Ko2M last year, and an indication of how his season went:




Or the Bryans’ rifles, and their mounted Garmins, and an indication of how their year went this season (similar to last):

 

[big5ifty]

It doesn’t take much more than common sense to realize that I did NOT imply every ELR match winner always uses a chronograph… but… I can state and demonstrate that highly successful ELR shooters do and ARE using chronographs on the line.

Common sense is a variable quantity, and it's never clear who has it and where it may or may not be.

Common sense is also not a one way street - "common sense for me and what I say, but not for thee and what you say."

I do agree the chrony is becoming a fixture on the competition line at all ranges, not just ELR.

I also do question the usefulness of it beyond load development. Whoever wins an ELR match with a chrony on their rifle does not win because of the chrony.

For example, in my simple previous case of adjusting the ballistic calculator for increase in ambient temperature - by the time it shows on the chrony you're already twp steps behind.

You know what the powder is going to do when the temperature increases, and how many fps per 5 degrees of temperature swing. You're not going to wait for it to show up on the chrony first.

Let's just agree to disagree on how important it is to know what your last shot velocity was.

 

[Varminterror]

I described in detail how ELR shooters - knowing how their trajectory changes with velocity - can make educated corrections which demonstrates why so many ELR shooters take advantage of having the tool at hand. Ignoring that fact is a strange choice - folks ARE using the chronographs on the line for that purpose, whether you understand the value in doing so or not.

 

[6.5 forever]

Not a good one.

I feel the same. Rifle recoil cannot be good on electronic circuits can it?