FX Chronograph vs Caldwell Precision Chronograph - FX was always slower.

[bltefft]

Well, I was looking for any excuse to do some shooting today and figured I'd shoot my new .22 Benjamin Marauder pistol (P-rod) with my FX chronograph hanging on the barrel at the same time I shot over my Caldwell Precision Chronograph.

As some may know, the new P-rod is a replacement for one that wouldn't hold air overnight. I'm still in the process of trying to seal the older one.

ANYWAY,

Here a synopsis of what I found out. The FX chrony always recorded a slower speed than the Caldwell, proportionally, it seemed. When the Caldwell reported a higher than average velocity, so did the FX and vice versa.

Here's the data:

The first table is when I shot JSB Diabolo Exact Jumbo Monster 25.39 pellets. When I weighed 10 of them, they averaged 25.07 gr, not 25.39.

The numbers for the Caldwell are on the left and those for the FX are on the right.

The second table is when I shot Benjamin Discovery PCP 14.3 gr pellets. When I weighed 10 of them, they averaged 14.36 gr, not 14.3.

I don't have a clue as to which one on my chronographs is the more accurate one, I guess I'll go with the Caldwell. because the numbers make me happier.

You reckon a squirrel could tell which gun fired the pellet that hit it in the head? - probably not, dead is dead.

Bobby

 

[Glem.Chally]

Are you sure the Caldwell isn't reading fast? It's a perspective thing I guess. With the fx app you can add or subtract 1 or 2% you can get them to align better if you choose.

 

[bandg]

Are you sure the Caldwell isn't reading fast? It's a perspective thing I guess. With the fx app you can add or subtract 1 or 2% you can get them to align better if you choose.

Exactly. Changes/consistency seem more important than absolute values in this case. And what is the absolute difference? About 1.5%?

 

[bltefft]

Here's a table of the differences:

 

[GeneT]

It's a pretty small difference, so I wouldn't worry too much about it. I've seen similar differences between Pact, CED and Oehler. Labradar tracks with Oehler pretty well, and I consider it "the standard" - but just pick one to trust and you should still see differences as appropriate.

GsT

 

[bltefft]

Are you sure the Caldwell isn't reading fast? It's a perspective thing I guess. With the fx app you can add or subtract 1 or 2% you can get them to align better if you choose.

I don't know if the Caldwell is reading fast or not. I do know about adding / subtract 1 or 2% to the FX. But since the differences seem small to me, and the Caldwell is my "goto" chronograph, I'm not going to worry with the FX.

It was fun running this little test, though.

 

[bltefft]

It's a pretty small difference, so I wouldn't worry too much about it. I've seen similar differences between Pact, CED and Oehler. Labradar tracks with Oehler pretty well, and I consider it "the standard" - but just pick one to trust and you should still see differences as appropriate.

GsT

Agreed. I wonder if I can conclude, "The heavier the pellet, the smaller the difference."?

 

[bltefft]

By the way,

A velocity of 8.9 fps (the average difference on the speeds of the 14.36 pellets) comes out to be 0.0025 FPE.

A velocity of 5.9 fps (the average difference on the speeds of the 25.07 pellets) comes out to be 0.0019 FPE.

So, I guess it really doesn't which chronograph I use.

 

[bltefft]

Are you sure the Caldwell isn't reading fast? It's a perspective thing I guess. With the fx app you can add or subtract 1 or 2% you can get them to align better if you choose.

Exactly. Changes/consistency seem more important than absolute values in this case. And what is the absolute difference? About 1.5%?

For the 14.36 gr pellets the absolute difference in velocity is 1.33% more from the Caldwell chrony. (0.01332734).

For the 25.07 gr pellets the absolute difference in velocity is 1.15% more from the Caldwell chrony. (0.011476366).

 

[Mwerks]

Mine does the same thing except my FX reads 10 fps faster.

 

[Jayson]

Mine does the same thing except my FX reads 10 fps faster.

My experience also, my Air crony and Caldwell align, my FX I run @ -2% to come close to match.

 

[PappiPT]

And as a last tuning, don't you adjust the speed/power to get the best accuracy? Regardles what the chrono reads?

 

[bltefft]

And as a last tuning, don't you adjust the speed/power to get the best accuracy? Regardles what the chrono reads?

What's what I would do. Ain't accuracy the bottom line?

 

[Dairyboy]

I wouldn't stress about it. The difference is so miniscule and there's no guarantee which one is more accurate. Plus both are in different positions and use different methods of recording speeds that I wouldn't stress about it in the slightest.

Call me crazy but aren't those speeds alittle slow for a Mrod?

 

[bltefft]

Call me crazy but aren't those speeds alittle slow for a Mrod?

Dairyboy, nope, you're not crazy, I was shooting my P-rod, not my M-rod, duh to me (besides my M-rod is .177, not even .22). I can't believe I did that. I was thinking hard, making sure my numbers were correct, and mistakenly called my Marauder pistol a Marauder rifle.

Thanks, for calling it to my attention. I went back and edited the text so that now it reads "P-rod". But now, readers won't know what you were speaking of, maybe after they will read this string they'll know what I did.

So for all you readers getting here late, in my first string, I said that I was shooting my M-rod, but I wasn't, I was shooting my P-rod.

 

[Dairyboy]

No problem my friend! We all make mistakes! Just wanted to clarify my confusion. Makes sense perfect sense being a prod.

 

[douger]

just a base line

 

[2D1C]

I ran a similar post recently my FX is off up to 50 fps! It was always a bit slower like yours which I was perfectly fine with. I looked around for a firmware up date but havent found anything. I think you are fine.

 

[CurtisNelson]

I get your point but I think a 6 FPS difference is trivial when your shot string is running an Extreme Spread of 76 FPS.

 

[1Sprayanimal1]

Thats what I was thinking. As long as you get a good idea. Start slinging lead.