Chronograph velocity 175fps slower than box

[Mackdog]

I am shooting a tikka t3x in 7mm-08 using hornady American whitetail ammo. Yesterday I shot through a chronograph and found it to be about 175fps slower than the published box data of 2840fps. Is this something to worry about or evaluate further? I shot 6 times with the following velocities
2633. 2657. 2661. 2736(this round did not group as well as the other). 2682. 2674. For an average of 2673

if I remove the 2736 the 5 shot average is 2661 fps.

I am planning to order the Leopold cds turret even though I am comfortable with moa and would like to be as accurate with my data as possible. Should I shoot through the chrono more? Or use the data I have of 2673/2661?

 

[Wyobohunter]

What barrel length did they test with vs what barrel length is your Tikka? Ammo companies like to post up big numbers and sometimes use long barrels to get those numbers. Also, every rifle is different. An identical make/model rifle might shoot faster or slower. I’d be more bothered by the 103 fps extreme spread and would try something else if you don’t intend to start handloading. A 100 fps extreme spread will open up those longer range groups but may not show itself at 100 yds. I wouldn’t even consider having a turret made until you find something with < 40 fps ES that also groups well at 100 yds. Then test the load at your max range. Then if everything looks good, have the turret made.

 

[Ucsdryder]

Lol the manufacturer exaggerated the numbers?!!!!! Say it ain’t so!!!

Oh and tikka barrels are known to be SLOW

 

[SDHNTR]

Box numbers are not reliable. Too many variables. Every gun is unique. I'm not surprised by your findings.

Shoot 12 times. Toss out your high and your low. Take the average of the remaining ten.

Go slow and let the barrel thoroughly cool between shots, several minutes. Don't let a round soak in a hot chamber. Aim and fire quickly. And if you really want to do it right, use a scope with a reliable erector system.

 

[Wyobohunter]

Lol the manufacturer exaggerated the numbers?!!!!! Say it ain’t so!!!

Oh and tikka barrels are known to be SLOW

I’d agree. Mostly because they tend to be on the short side. I bet his bbl is 22”. The test bbl could have been 26”. That could easily account for as much as 160+ fps.

 

[Mackdog]

the tikka has a 22.4 in barrel. I believe the box test data is from a 24 inch barrel. I do not have plans to hand load right now. It’s something I may do in the future but don’t have any equipment for it now.

 

[Wyobohunter]

87.5 fps per inch in on the high side if your math for 175 fps difference is correct. But it’s not alarming. Especially if you have a new barrel. It will speed up when broken in. BTW, I’d also wait on a turret until it is broken in if it’s new. I’d still find a different load. That ES is unacceptable IMO.

 

[Dioni A]

Tikka's are consistently slow barrels and ammo manufacturers are usually optimistic about their speeds.

 

[Wyobohunter]

Tikka's are consistently slow barrels and ammo manufacturers are usually optimistic about their speeds.

I haven’t found the slow barreled Tikka thing to be the case in my relatively small sample of two. 30-06 and .243 Win. My 30-06 is slow now but it wasn’t before I hacked the barrel down to 18”. There may be some truth to it but I also wonder if the slow barrel stigma comes partially from a combination of:

Lots of new shooters + Tikka popularity + chronographs becoming more common + new shooters testing new barrels + new shooters not getting the most out of their rifles by handloading.

 

[Mackdog]

I have probably shot 200-250 rounds through it so far. I have been happy with how the hornady ammo groups but I also did not like the one round at 2736 fps. If that was an anomaly and I remove it, the 5 shot group varies by 49fps. I will shoot some more through and also try some different ammo as well.
I figured that ammo manufacturer’s may exaggerate some but I didn’t know I would be that much off.

 

[Wyobohunter]

Also, to the OP. 175 fps difference is not a huge deal so long as it’s consistent. I’ll keep saying this part until I know you see it. The big extreme spread is a big deal. Play around with a ballistics calculator and you’ll see what I mean on both points.

 

[Mackdog]

Ok glad to know the 175fps is not a worry. I have been using my ballistic program and do see how at longer ranges it can make a big difference. I definitely don’t want a round 100fps faster than what I am planning for.

 

[BjornF16]

What chronograph are you using?

They are not created equal…

 

[SDHNTR]

And more erratically.

 

[Mackdog]

And. Is your barrel new? A new barrel can shoot 100 fps slower than it will shoot after it’s broken in.

200-250 rounds shot through it so far

What chronograph are you using?

They are not created equal…

I do not know what kind of chronograph it was.

 

[Wyobohunter]

200-250 rounds shot through it so far


I do not know what kind of chronograph it was.

I deleted my post/question after I saw you’d already answered that. Your barrel should be broken in by now.

 

[TxxAgg]

Tikka Speeds w/Factory Loads

Just putting this here for data points. We chronographed a few loads yesterday and will do a few more today. T3x 6.5 Creedmoor (24.3") Hornady 147 eld-m Avg 2600 fps Federal 140 non-typical Avg 2680 fps *****Same gun cut to 21"*** Hornady 147 eld-m Avg 2500 fps Federal 140 non-typical...

www.rokslide.com

 

[Rob5589]

The velocity deviation is more concerning. There was more than 100 fps difference between the high and low and over 50 fps if you throw that high one out. Unfortunately you have to pick the average and hope that you don't end up with a faster or slower than ave round at the time of the shot.

 

[Shootinsurveyor]

Don't worry about the Chrono if you aren't reloading. Zero at 100 and get to a distance 3-400 yards away if you can. shoot a group and measure the drop. True your calculator with the drop info and it will tell you how fast you are going.

I thought a chrono would be the easy button for shooting out further. Still have to true the data to real drops so I just don't use the chrono unless I'm testing velocity in reloads. Even when I get a load I like, I still true the data with actual drops.

My tikka averages 100fps slow on some factory loads. It is a hammer though once you find what it likes.

 

[zion zig zag]

Don't worry about the Chrono if you aren't reloading. Zero at 100 and get to a distance 3-400 yards away if you can. shoot a group and measure the drop. True your calculator with the drop info and it will tell you how fast you are going.

I thought a chrono would be the easy button for shooting out further. Still have to true the data to real drops so I just don't use the chrono unless I'm testing velocity in reloads. Even when I get a load I like, I still true the data with actual drops.

My tikka averages 100fps slow on some factory loads. It is a hammer though once you find what it likes.

So this is probably a dumb question: is there a ballistic calculator that solves for velocity? If I have BC, environmental, bullet weight and drop, will one spit out a speed? And then is that speed valuable for longer shots?