Real muzzle velocity on factory ammo

[Tikka T3X]

Hi folks.
Let's everybody who had information about real muzzle velocity on factory ammo by different sizes barrel length in .308 or even different calibers checked by chrono let's share here to compare with the factory information showed on the boxes.
For example recently I found it out that in .308 Geco Expres muzzle velocity shown on the box was 820m/s, but shouted from 600mm and 570mm barrel length Tikka t3x we found out that the real velocity was between 795- 805 but not more.
So if anybody else met the same problem let's share it here.

 

[Wilf102]

Funnily enough I chronod some Gecko today. 7x57 165 gr in a 22 inch barrel. It came out at 2619 but the box quote is 2542. So I am up on the deal! 798m/s v 775m/s in modern money.

 

[John Gryphon]

I think you are up on the deal too ..with 265 grains

 

[Shootgun]

Recently measured some .270 and 7mm RM RWS HIT.
.270 130 grains - 921m/s stated by manufacturer, real life 883m/s
7mm REM MAG 140 grains - 940m/s stated by manufacturer, real life 890m/s

 

[Jon Smith]

I would think that there are too many variables for this data to be of any worth worrying about. The main ones being you are not using the factory test barrel or a chrono that is calibrated.
Any deviation from from the test barrel, the atmospheric conditions and of course your chrono will show itself in the velocity. Checking the velocity and measuring real world drops to compare is useful in as much as you know what is going on with your particular rifle, it's a bit like the 'do you have a load for my insert make model here that works well?'

 

[Highlandsjohn]

I think you are up on the deal too ..with 265 grains

A tad on the heavy side

 

[tackb]

140 eld-m factory creedmoor , 2700fps from my 20" bartlein barrel

 

[Wilf102]

Good spot. Now corrected. It then again, Sussex Fallow are the same size as Cape Buffalo. Or feel like it when dragging them out!

 

[John Gryphon]

Good spot. Now corrected. It then again, Sussex Fallow are the same size as Cape Buffalo. Or feel like it when dragging them out!

I knew it was only a typo but like the rest here I couldn't resist having a dig lol.

 

[kenbro]

OP is asking if anyone has the same problem, what is the problem?
Thanks,Ken.

 

[20-250]

I feel that if you are able to see such minor differences in claimed and actual muzzle velocity as a problem, you should count yourself lucky that you have gone through life so far without having had an actual problem!

 

[stubear]

I was over-thinking all of this about a year ago.

I came to the conclusion I should be asking myself the following questions;
- Is it acceptably accurate?
- Does it get my quarry down reliably?
- Does it shoot with an acceptable degree of flatness out to the ranges I am likely to be shooting at?
- Is the cost of the ammo per box acceptable and can I get a regular supply of it?

If the answer to all of those questions is yes then jobs a good 'un, you have found a good round so crack on.

I've been messing around with some home loads on the side for a while now (thought I had one nailed a while back but further testing did not fully convince me!) and I've yet to construct a load that I'm as confident with as I am with factory Federals... Its an interesting little mental exercise I keep turning over on the side because puzzles like this get stuck in my brain and I cant leave them alone, but frankly if you can get a decent factory round that does the job I figure I'd rather go stalking!

 

[Grandhubert]

Hi folks.
Let's everybody who had information about real muzzle velocity on factory ammo by different sizes barrel length in .308 or even different calibers checked by chrono let's share here to compare with the factory information showed on the boxes.
For example recently I found it out that in .308 Geco Expres muzzle velocity shown on the box was 820m/s, but shouted from 600mm and 570mm barrel length Tikka t3x we found out that the real velocity was between 795- 805 but not more.
So if anybody else met the same problem let's share it here.

Different loads shoot to different speeds in different barrels, as well as to different accuracy standards.

The drop in velocity you have described above is 20 m/s or around 65 fps from advertised in your slightly shorter barrel.

To give this some perspective consider that a round from your rifle has the same impact energy at 100 yards that the same round fired at factory spec possess at 75 yards.

You would be hard pressed to see a difference in terms of notional terminal effect between the two, in other words.

In terms of the effect on trajectory that 65 fps might make a half inch of difference past 300 yards, again negligible.

 

[SpikeD]

I think Stubear and Grandhubert cover the real life side of the question here but as a rule of thumb I've always found RWS to be the closest to their published figures. US loaded factory is downright wimpy in comparison. I tried some 173gn 7x57 Winchester and it was 200fps lower than advertised. The RWS was 30fps less. Norma is generally pretty close and the Kynamco .416 Rigby I tried was dead on though the brass was terrible with neck splits on first firing.

to be fair there are so many variables that come into play and often some creative marketing, if you look at old Kynoch catalogs they were using 28" test barrels for many calibres so perhaps set some unrealistic expectations early on for others to follow.

 

[Laurie]

I think Stubear and Grandhubert cover the real life side of the question here but as a rule of thumb I've always found RWS to be the closest to their published figures. US loaded factory is downright wimpy in comparison. I tried some 173gn 7x57 Winchester and it was 200fps lower than advertised. The RWS was 30fps less. Norma is generally pretty close

Quite so on the general point.

On US ammunition, much depends on the cartridge's age and history. Whilst RWS and Norma will load up historic military cartridges to near full CIP average pressures, IME and chronographing a mix of makes, American companies load 6.5X55 and 7X57 to 40,000 psi or less. As well as being way below spec, this can produce other issues such poor obturation / dirty brass / dirty barrels and huge ES spreads due to inefficient combustion. I tried some Hornady 140gn PSP in a match rifle a few years back and as well as being two or three hundred fps deficient on the claimed MV, ES values ran at 140 fps! Pressures were likely only around 35-38,000 psi - ie the same levels as US companies load 8mm Mauser to given its known bullet size 'problems'. A very poor product indeed!

 

[Dan Newcombe]

Hornaday Superformance make some pretty bold claims on the box for the .22-250 that i use.

Would be interested to chronograph them and see what they are doign out of my rifle but until then i am happy with the fact that they are pretty accurate and put things down pretty hard.

The real life speed starts to matter when you are dialling and getting further out there and the published velocity is a way off the pace!

 

[Border]

Hornaday Superformance make some pretty bold claims on the box for the .22-250 that i use.

Would be interested to chronograph them and see what they are doign out of my rifle but until then i am happy with the fact that they are pretty accurate and put things down pretty hard.

The real life speed starts to matter when you are dialling and getting further out there and the published velocity is a way off the pace!

Was it not this ammunition in 243W that blew up an X bolt a while back? Have heard several reports of stiff bolts with it. Maybe a bad combination with badly copper fouled barrels raising pressure excessively??

 

[WildBoarHunter]

308 win 20 inch barrel Hornady Superformance SST 165 gr, factory 866 m/s, real 822 m/s, 44 m/s loss

8×57 IS 21 inch barrel Geco Plus 196 gr, factory 785 m/s, real 840 m/s, 45 m/s loss

Generally speaking, I noticed velocity loss of about 45 m/s everytime I measured it, including home loads made by reloading manual data. The average loss of 45 m/s was in a 20 barrel 308 and 21 barrel 8×57. So I'd say 8mm looses a bit more velocity with short barrel, than 308 win. The latter is by far the most appropriate for short 20 barrels as the recoil and blast are still mild, compared to 8×57 and 30-06.

Right now I'm waiting for a Heym SR-21 Allround with a 55 cm (21,6 inch) barrel in 30-06 and I'm very courious about velocity loss. 21.6 is pretty short for 30-06.

 

[John Gryphon]

I wonder if the manufactures should/could be held accountable. EG advertising say 3000 fps for instance when you are actually chronographing 2875.
Simple eh! You are buying on the strength of their blurb stating the speed you desire but you are not often getting that speed.

 

[Grandhubert]

On the other hand guys federal bluebox 100gr 243 ammo shoots right at 3000 fps in my 22" remington, Norma 150 gr semi point 3006 ammo shoots right at 2910 in my 22" tikka and Remington premier 150 gr Nosler BT shoots right on the money in my sako 308.

Different rifles chaps, different rifles behave differently...