IS MY CHRONOGRAPH IN NEED OF CALIBRATION?

[WoodyP]

I recently bought a new Chrony Master chronograph.  The readings I am getting on all calibers I've shot through it, seem to be a couple hundred feet slow.  Or are the reloading manuals, and posters on gunsites stretching things?
25-06 NEF Handi-Ultra,26 in barrel,  75 gr bullet, 58 gr H4831sc, 3365 fps
.308 Win, Belgian made BLR,  165gr bullet, 50 gr IMR4350, 2590 fps
                                                               41 gr IMR3031, 2445 fps
                                                               45 gr IMR4064, 2605 fps
                                            150gr bullet, 43.5 gr IMR4064, 2482 fps
                                                                45 gr IMR4064, 2609 fps
45-70 Marlin 1895C, 26in barrel, 350 gr bullet, 40gr, IMR4198, 1695 fps
                                                                54 gr IMR3031, 1878 fps
                                                                 45gr IMR4198, 1880 fps
I don't know whether to contact Chrony, or if these velocities are realistic.
Regards,
Woody

[R.W.Dale]

I think that your chrony is fine, one thing I've learned with mine is that claimed velocities weither they be handloads or factory ammo seldom live up to claims. I'm not at all suprised anymore when a load chronoghaphs a couple of hundred feet per second slower than the manual claims.

 It has been said that you never want to chrony your favorite hunting load

[Gregory]

Test it with some 22LR MATCH ammo, these should be pretty close to advertised MV.

[Jerry Lester]

Your velocities sound about right to me. I doubt your chrono is giving you false readings.

Mine went haywire one time, and was reading my favorite 223 groundhog load at something like 173 fps, and a friends bow registered 8,000+ fps! Needless to say, we pretty much knew it was the chrono that time! LOL!

[EsoxLucius]

Make sure the unit is completely unfolded and you have good light conditions.

[Lone Star]

Handloaders inexperienced with chrongraphs somehow expect factory loads (and handload data) to give the same velocities in every like-chambered firearm on earth.   :-D    I've used an Oehler M33 for over twenty years, and in my experience handload velocities are as likely to be high as they are low.  Why? Powder lots can vary by 3% in burning rates.  Primers have different brissance and this effects the powder burning rate. Barrel bore diameter can vary by over 0.0005".  Some bores have wide lands, some have narrow lands - guess which give higher pressures/lower velocities?  Some chambers have longer throats, or throats with larger diameters.  All of these effect the velocities that some seem to think are "guaranteed" by the loading manuals or the factory cartridge makers.

The data the OP gives above are a perfect example.  Using Hornady #6:

.308 150-grain, 44.9/45 grains IMR4064
Woody = 2609 fps
Hornady = 2700 fps
Woody gest 91 fps less that the manual predicts.

.45-70 350-grain, 53.9/54 grains IMR3031:
Woody = 1878 fps
Hornady = 1800 fps
Woody gets 78 fps more velocity than the manual predicts.

Since the velocities the Chrony gives bracket what one would expect, I'd say the instrument is just fine.

.

[longwinters]

I had the same depressing experience when I bought my chrony.  Asked the same questions you have and got the same answers.  I tried several rifles and loads in mine and all were slower than my Nosler manual and what " everyone else" said they were getting.  I think Krochus had the right idea.  Many a great load has been ruined for a shooter who gets hung up on velocities.  I have tried different lots of powder, bullets and primers and found it makes little if any difference in my cartridges velocities.  Of course this is only my experience.

Long

[Lone Star]

I had the same depressing experience when I bought my chrony.

So like the OP you got 78 fps more velocity than the manual predicted and you're depressed?  How odd......how did your velocities compare to the Hornady, Sierra, Lyman, Speer, Alliant, Accurate or Hodgdon manuals?  Using a single manual as a reference point is not very enlightened.  

[longwinters]

Woody,

Actually Sierra's seemed to be more on the mark for my rifles. But I use Nosler because I use more of their bullets than any other kind.   I also have Speer, Hornady and a couple of different powder manuals.

What I have found is to find a few guys that dont seem to blow a lot of smoke on the internet just to hear their gums flap and see what their experience has been.  It is not hard to see who is who after reading a while on the forums.  Then put it all together and see what you come up with.  

I do not speak as any type of expert, just a guy learning from scratch one load at a time.  And I have had the same questions as you have in the past several years.

Long

[WoodyP]

Just to clarify Lonestar.  My Hornady manual #4 list 44.9 gr IMR4064 at 2800, from a 22" barrel.  I'm getting closer to 2600.  The Hornady manual says 3800, for 60 gr of IMR4831 in a 24" barrelled 25-06 with the 75 gr bullet, I,m just breaking 3300 with a 26" barrel.  My 45-70 barrel is 4" longer than the test barrel etc.   All of the info I see, says to expect 30-50 fps increase per inch on the average.   I am also about 200 fps shy of every load and velocity I see posted on the net.  I'm not really worried about velocity, I just want to make sure my chrony is working right.  I've been handloading for 35 years, so I know what loads will kill the animals I'm after.  In fact I normally load in the 2400-2600 fps range, as I've found that bullets seem to perform best at that speed, and the game dies quicker.
Best Regards,
Woody