chrony on factory loads

Hi All, i havent shot factory ammo for 15yrs but got asked to sight in a friends rifle for him, i thought while i was at it id run the loads over my labradar, its a remington 783 in 243 shooting winchester super x 80gr projectiles. the box says 3300 ish and my radar says 2740.... it wouldnt surprise me to be 100 or so out but 600fps almost??...

could i suspect its old degraded ammo or a slow short barrel? my labradar reads what i expect on all my handloads so i dont think it would be that.

Interested to hear what others have experienced.

I have been very surprised by the lack of velocity from factory Winchester ammo. My 7mm08 was 250fps slower then the box advertised in saying that it was a 20inch barrel. And I cronographed factory winchester 270wsm ammo with a 24 inch barrel at 2960fps. And the box stated 3150

Read the fine print about the velocity on the packet. generally it is from a 24 inch proof barrel.

Be about right. Every factory round i’ve ever put over a Chrony is well below stated MV

Your point? Read above with the same length barrel

Also, how many rounds did you check the speed on? There can be a reasonable variance there too.

Quote:

---

Originally Posted by Wake

Your point? Read above with the same length barrel

---

Welcome to my ignore list

The only factory ammo that I've tried that matched was hornady superperformance 7mm rem mag which was 50 fps average above box claim for a 3 shot string. Fired at the same time some federal blue box was 280 fps slower. Rifle was a saur 100

as far as the barrel length goes, ive heard 50fps an inch (ish) so maybe 200 not 600... and it was average over 14 rds. rds varied from 2740 to 2805

Yup same here, i have 100x sako 55gr 22250 rounds, and in my ackley chamber they chrony 3360fps with the magneto speed vs packet velocity of around 3600fps. 23" barrel, but it is also being fireformed.

On the other end, i have a 308 with a 20" barrel and an obermeyer chamber (tighter than saami) and i actually get pressure signs with sako 150gr factory ammo, and it measures ar 2850 which is faster than i think the 2800 on the packet

I've seen speeds listed as coming from 24 to 28 inch barrels, so worth checking if you can find it. Even then I've found the packaging to be on the optimistic side. Some calibers are worse than others eg 6.5x55 due to all the old rifles in it.

I had a mate using PPU shooting at some young stags, only had a couple rounds and I had some Winchester on me. I figured why carry a rifle when we use the same calibre. Anyway, I gave him my ammo and the Winchester made the PPU sound like they were suppressed.The PPU is supposed to be faster on the box...

Yeah hornady always get good speeds. My 18" .308 gets 2670 with the 168gr eldm that's only 170fps slower. Surprisingly the Winchester 150gr PowerPoint was getting good speeds too at 2650(box states 2820)

Quote:

---

Originally Posted by NewbieZAR

Yup same here, i have 100x sako 55gr 22250 rounds, and in my ackley chamber they chrony 3360fps with the magneto speed vs packet velocity of around 3600fps. 23" barrel, but it is also being fireformed.

On the other end, i have a 308 with a 20" barrel and an obermeyer chamber (tighter than saami) and i actually get pressure signs with sako 150gr factory ammo, and it measures ar 2850 which is faster than i think the 2800 on the packet

---

Greetings NewbieZAR,
Your Ackley Improved chamber will reduce the velocity of factory loads significantly whether a fire forming load or not. 240 fps does not sound out of order. Also for all the reduction in velocity in non magnum cases generally works out to 20 to 30 fps per inch below 24 inches. Loads for many cartridges have been dialled back by the manufacturers due to the more accurate pressure reading equipment now in use. The .243 Winchester and 7mm Remington magnum have lost most. Published load data has been dialled back as well. The published data for factory ammo has not always followed.
Regards Grandpamac.

Well box factory ammo is nearly always tested with 24 inch proof barrels , sometimes 26 inch. Most seem to test less than stated but will by some point
anyway if using a shorter barrel. Couple i tried in factory over a chrony were only 50-90 less and that was with a 24 inch barrel.
Also, as im not sure(someone will know) arent factory box speed from straight from the muzzle? (other than a few feet with a chrony) Just thought i read that somewhere.
Plus a top end chrony will be more accrurate than some cheaper models and different rifles barrels will affect the speed also.
they never going to be perfect

Quote:

---

Originally Posted by deer243

Well box factory ammo is nearly always tested with 24 inch proof barrels , sometimes 26 inch. Most seem to test less than stated but will by some point
anyway if using a shorter barrel. Couple i tried in factory over a chrony were only 50-90 less and that was with a 24 inch barrel.
Also, as im not sure(someone will know) arent factory box speed from straight from the muzzle? (other than a few feet with a chrony) Just thought i read that somewhere.
Plus a top end chrony will be more accrurate than some cheaper models and different rifles barrels will affect the speed also.
they never going to be perfect

---

Factory ballistics are "corrected to the muzzle". This means that the velocity is raised a little from what you would read on a chronograph. Generally the difference is small. 10 or 20 fps.
GPM

Quote:

---

Originally Posted by stuart165

Hi All, i havent shot factory ammo for 15yrs but got asked to sight in a friends rifle for him, i thought while i was at it id run the loads over my labradar, its a remington 783 in 243 shooting winchester super x 80gr projectiles. the box says 3300 ish and my radar says 2740.... it wouldnt surprise me to be 100 or so out but 600fps almost??...

could i suspect its old degraded ammo or a slow short barrel? my labradar reads what i expect on all my handloads so i dont think it would be that.

Interested to hear what others have experienced.

---

Are you shooting from a tikka or sako? They have a bit of a reputation for slow barrels

its coming out of a remington 783

Quote:

---

Originally Posted by stuart165

its coming out of a remington 783

---

Could just be a massive chamber and freebore.....tho 600fps is a hell of a lot.

Been a while since I crohnyed any factory ammo but I remember doing 308 fed blue box threw my standard Sako and being surprised it was within 50-60 fps of what the box said.
I was surprised at the time because of the wildly held beleif that the box fps is very optimistic....in that case it was pretty bloody close I thought considering the 22ish inch barrel of the Sako