650 fps Slow Barrel??

ozzy-yyc · Oct 14, 2018

Hi all,

Having a minor crisis a couple days before hunting season and was hoping someone could help put my mind at ease!

I was sighting in yesterday. I zeroed at 200 meters (219 yards). Ballistics say I should be approx. 2.5 inches high at 100 meters (110 yards), but I was actually 4.5 inches high! So my ballistics are WAYYY off of expected.

Published velocity of my ammo (Nosler Trophy Grade 180 grain AccuBond 30-06) is 2750 fps, but this implies an actual velocity of 2100 fps. Is that kind of difference normal??

I'm shooting a relatively new (less than 500 rounds) Tikka T3x Light Stainless 30-06. Below are links to my expected vs actual ballistics calculations.

Expected: ShootersCalculator.com | Expected

Actual: ShootersCalculator.com | Actual

I have no choice at this point but to assume this is true, as I don't have time to get a chronograph and a bunch of types of ammo to experiment with. I'm just wondering if this seems normal or totally crazy. I should note, I was shooting accurate groupings of approximately 1 to 1.5 MOA. Pretty happy with everything other than my ballistics.

Gerald Martin · Oct 14, 2018

Published ballistics are probably from a 26" + test barrel. I wouldn't be too surprised to hear you are shooting much slower velocities than that. IMO, shooting 180 grain factories out of a 30-06 doesn't is not the optimal compromise in energy/bullet drop. I shot one box of 180 grain Corelockts through my gun. Upon finding out my bullets were dropping over 16" at 300 yards with a 100 yard zero, I dropped to 165's and eventually settled on 150 gr. Barnes X's.

ozzy-yyc · Oct 14, 2018

Gerald Martin said:
Published ballistics are probably from a 26" + test barrel. I wouldn't be too surprised to hear you are shooting much slower velocities than that. IMO, shooting 180 grain factories out of a 30-06 doesn't is not the optimal compromise in energy/bullet drop. I shot one box of 180 grain Corelockts through my gun. Upon finding out my bullets were dropping over 16" at 300 yards with a 100 yard zero, I dropped to 165's and eventually settled on 150 gr. Barnes X's.

Thanks Gerald. I do agree. Only problem is mine is dropping 26" at 300 yards with a 100 yard zero, not 16". So it seems wayyyy slow. Accurate though! The gun shoots that ammo really well!

MThuntr · Oct 14, 2018

sounds like you need a chronograph and some new ammo. I can't offer much on the velocity issue...I know it's not uncommon for velocities to be a couple hundred fps off from published.

Swiftus · Oct 14, 2018

Nosler states they typically uses a 26" barrel to test their ammunition. Your barrel is shorter (22.6"), so there should be some velocity lost there. I've read that a good rule for rifles is about 20 to 25 fps per inch lost. That would be a loss of 80 to 100 fps. Also, they state in their FAQ that some barrels can vary as much as 150fps from each other. Adding these together and you have somewhere between 1/3 and 1/2 of the fps loss you are experiencing.

Other than that I don't know.

VikingsGuy · Oct 14, 2018

Something seems off. 100-200 fps for the shorter barrel is to be expected, but 650 suggests something else is amiss. If you have a buddy who has a chrono it may be worth a couple of rounds, as 2100 fps would be a pretty low starting point and would limit your terminal ballistics effective range significantly (including bullet expansion).

mtmuley · Oct 14, 2018

Find a chrony. No way you are off 650 fps. mtmuley

belly-deep · Oct 14, 2018

I really doubt your muzzle velocity is 2100.

As a poster above said, you lose about 25 FPS per inch as a general rule. I’ve chronographed about 5 different Nosler loads and they have all been pretty zippy. I actually think Nosler loads a little hotter than Remington, Winchester, and Federal.

I had a 3006 that shot abnormally low at 200. I never did figure out why, but I did chronograph the gun and it wasn’t shooting slow like you would guess. It must have been from something else, and I sold it a few years later.

I have a 280 that shoots so far to one side it is hard to get zeroed. After discussing it with a gunsmith, I’ve come to the conclusion that likely the barrel was not threaded perfectly square and the barrel cants slightly to the side. I’m don’t know why that couldn’t occur with a barrel canting slightly down.

I’d try to find a friend with a chronograph. Once you know your actual velocity, you can start trouble shooting.

Bambistew · Oct 14, 2018

Did you shoot it at 300 yards? Or assuming the drop from the 200 and 100meter range poi?

I doubt you're 26 inches low with a 2 inch high at 200. I'll bet you're 6-8 if you shoot it.

ozzy-yyc · Oct 14, 2018

Bambistew said:
Did you shoot it at 300 yards? Or assuming the drop from the 200 and 100meter range poi?

I doubt you're 26 inches low with a 2 inch high at 200. I'll bet you're 6-8 if you shoot it.

It's calculated based on: I figured out what my velocity would have to be in order to be zero at 200 meters and 4.5" high at 100 meters, which is what I was experiencing. Velocity would have to be 2100. Using 2100, I plug in 100 yards as my zero and look up what the bullet drop would be at 300 yards (because Gerald Martin suggested he was 16" low at 300 yards with a 100 yard zero, I wanted to compare apples to apples). It would be 26" low.

ozzy-yyc · Oct 14, 2018

belly-deep said:
I really doubt your muzzle velocity is 2100.

As a poster above said, you lose about 25 FPS per inch as a general rule. I’ve chronographed about 5 different Nosler loads and they have all been pretty zippy. I actually think Nosler loads a little hotter than Remington, Winchester, and Federal.

I had a 3006 that shot abnormally low at 200. I never did figure out why, but I did chronograph the gun and it wasn’t shooting slow like you would guess. It must have been from something else, and I sold it a few years later.

I have a 280 that shoots so far to one side it is hard to get zeroed. After discussing it with a gunsmith, I’ve come to the conclusion that likely the barrel was not threaded perfectly square and the barrel cants slightly to the side. I’m don’t know why that couldn’t occur with a barrel canting slightly down.

I’d try to find a friend with a chronograph. Once you know your actual velocity, you can start trouble shooting.

Yeah I'm gonna try a new box of ammo from a different lot first just to be sure. If I get the same result, I'll be getting a chronograph, making a test plan, and taking very detailed notes.

cahunter805 · Oct 14, 2018

I’d suspect it’s a scope issue. Parallax issue or scope mount issue!

Tikka06 · Oct 14, 2018

I shoot the 165 trophy grade accubond load in my T3 superlite 06 and it was a little slower than the box stated. But I think maybe only like 25-50fps. I expected that due to barrel length. I can't remember the exact specifics, as they are not in front of me right now. Gerald, how do you like those Barnes x's in 150?

Don Fischer · Oct 15, 2018

You have this same thing on another site. You really want to get comfortable with your rifle or do you want to nit pic? Sight in 3" high at 100 yds then shoot it at different ranges out to 300yds. Forget the velocity,only thing that matter's is what the load does in your rifle. Shot the same ammo in three different rifle's over a chronograph and you'll get three different ave velocities! 3" high at 100yds and out to something like 270-300yds the bullet will never be over 4" high or 4" low. If you need your rifle to shoot 500 yds, don't worry about it, it'll still shoot 500yds. You just probably won't be able to hit anything with it. All this ballistics hocus pocus is just something for guy's to talk about!

ozzy-yyc · Oct 20, 2018

Update:

New box of ammo and all is good in the world again.

At first, I didn't change a thing on my rifle or scope. It was set up zeroed at 200 meters based on my previous box of ammo. Well, my first 3 shot group at 200 meters this time? Almost 9 inches high!! (i.e. my theory that the last box was slow seems to check out).

So, I re-zeroed for the new ammo (if you haven't been following along - same ammo, different lot number). Now for the real test: how high is it at 100 meters? It should be about 2.5 inches high, but last time was 5 inches high... Success! My 100 meter groups are ~2.5 inches high. Perfect.

I'm much happier knowing I had a bad box of ammo than finding out something was wrong with my rifle or scope 3 days before my first hunting trip of the season.

BAKPAKR · Oct 20, 2018

I am glad to hear your problem has been resolved. Good luck hunting.

nhn2a · Oct 21, 2018

That seems like a pretty large difference for that lot. Did you contact Nosler by any chance? I've never used them but have always heard they make great ammo so just curious what their response was if so.

88man · Oct 21, 2018

I just can't believe this is a velocity issue. Shoot the gun at 100-200-300 and chart, even at a farther range.

Bambistew · Oct 21, 2018

Did the bad ammo kick about like a 243?

ozzy-yyc · Oct 21, 2018

88man said:
I just can't believe this is a velocity issue. Shoot the gun at 100-200-300 and chart, even at a farther range.

No more of the "bad" ammo, so I can't. But at the time I did shoot it multiple times at both 100 and 200 (meters, not yards) and it was very consistently 5 inches high at 100 meters when zeroed at 200 meters. All previous ammo and the new stuff: 2.5 high. That sorta says it all right there.

According to Nosler, the "bad" ammo I had was a lot from over 3 years ago. Think that could make a difference somehow? Sorta pisses me off considering I bought it brand new from Cabela's less than a month ago.

650 fps Slow Barrel??

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