Speed difference between reality and what's on the box

[D-mon]

Hi,
Today I was helping a friend shooting his factory Remington 700 xrc in 7rem mag at 900 yards. He was using factory hornady precision hunter ammunitions. That ammo is supposed to have a velocity of about 2940fps .
We chronographed it at 2766fps. When running that speed through Balistic AE we were bang on the 22.5moa of drop announced for 900 yards with his set up and the current atmospheric conditions (25 deg Celsius , warm afternoon). So no problem on that side.
But I was really surprised to see that ammo going close to 190fps slower than what is was advertised for , specially in a 26" barrel.
Have any of you noticed that much difference with that ammo?

 

[Deleted member 115360]

190fps seems pretty extreme

Seeing 20 or even 30fps isn't out of the norm, but 190fps hardly seems possible. I'd say there is a problem there. Maybe the chronograph needs calibrated or something. What was the ES?

 

[Deleted member 115360]

I just noticed that you were from Scotland. I figured your chronographs measured in haggis per kilt or something anyways.

I don't know how to convert HPK to FPS. Could be the problem.

 

[LVJ76]

I've had this happen the other way around.

Federal Premium 7mm Rem Mag with 168gr Berger Hybrid Hunter, it's advertised at 2,870 fps and Im getting 3,055 fps. That's a 185 fps difference in my Rem 700 with a 26" barrel.

 

[Deleted member 115360]

I've had this happen the other way around.

Federal Premium 7mm Rem Mag with 168gr Berger Hybrid Hunter, it's advertised at 2,870 fps and Im getting 3,055 fps. That's a 185 fps difference in my Rem 700 with a 26" barrel.

I wish I had that problem. Does it shoot all ammo fast, or is it specific to that cartridge?

 

[LVJ76]

No clue, I've never checked any factory ammo, I had only gotten it for the brass.

In this case I had been wanting to try out some Berger and had some loyalty points at sportsmans I had to use so I got some of this Federal Premium ammo, I was surprised how fast it shoots.

 

[D-mon]

I only tested one round, so not the best conclusion, but that speed input into the ballistic app exactly matched the trajectory at 900yrds. I am in the south hemisphere currently and i have not updated my location.

 

[MagnumManiac]

It is not uncommon to get higher or lower velocity than what's on the box.
It's just as likely to get the exact velocity, as I did in my 24" 25-06. 5 consecutive shots with Winchester 120gr EP ammo ran 3030fps, which is exactly what the box said.

I only bought it to run in the barrel and decided to run the 5 remaining rounds over the chrony.

Cheers.

 

[Dosh]

Manufacturer's embellishments are not uncommon. With mass production they can't effectively have a grasp on actual numbers.

 

[badthirtyone]

I just noticed that you were from Scotland. I figured your chronographs measured in haggis per kilt or something anyways.

I don't know how to convert HPK to FPS. Could be the problem.

Possibly one of the most underrated comments in the history of this forum. Don't know why this hit me so funny, but I laughed for at least 5 minutes.

 

[codyadams]

It is not at all uncommon, often times you can see more than that. An extreme and more rare example, my buddy had a box of federal premium vital shok 165 grain spbt 30-06 ammo, and after a 200 yard zero, was hitting excessively low at 400 yards. I checked his velocity, and he was consistently at 2050 fps. Yes, 2050. Box stated 2800. Pulled three bullets, consistently 56.5 grains of an extruded grain powder, so a roughly appropriate charge of an appropriately selected burn rate powder, I assumed they just used the wrong powder, an excessively slow one. Checked on their site, no ammo recalls, so I called them. They said sorry and sent a free box of ammo.

I have had a couple friends with the hornady precision hunter ammo get above and under on stated velocity, however one consistent thing was that their extreme spread was all pretty big, around 50-80 fps.

 

[Deleted member 115360]

Possibly one of the most underrated comments in the history of this forum. Don't know why this hit me so funny, but I laughed for at least 5 minutes.

Thank you.

My humor often feels unappreciated here. I figure I get some laughs, but most of the folks here want to appear too laconic to laugh in public.

 

[Rick Richard]

Never trust what is printed on the box or what someone says. Every barrel is different that is why a chrono is so important.

 

[kiwikid]

RWS factory ammo also seems to be somewhat slower than what is listed on the box. A couple of years ago I mounted a scope on a second hand Carl Gustaf 3000 rifle and sighted it in for my Cousin using his RWS 140 grain Double Core factory ammo.
The box lists a velocity of 2855 fps but through the 24" barrel I only saw 2585 fps. However for the 4 shots I chronographed the ES was 3.37 fps with an SD of 1.82 fps. Even though it was slow it turned in a < 0.6" 5 shot group at 100 metres.