Can anybody help me with velocity?

[Hook'N'Bullet]

I know it's a bit of a long shot but could anybody tell me the rough speed of factory Sakos 150gr Super Hammerheads in .308 out of a 20 inch barrel?

OR

Factory Federal Premiums Nosler BTips in same weight/set up

Or better yet, if somebody has a chrony figure for this set up?

Without owning a chrony, I'm trying to get a BC calculator running and they're advertised at 2805 fps but that definitely won't be an accurate number for my 20 inch barrel. I know the general rule is 50fps per inch (test barrel 24inch ?) But I've read other say it's as low at 25fps per inch.

If this fails, I'll have to shoot at zero, shoot at 200 and mess around with speed in the app to match the drop etc. It would be handy if somebody had the same set up and save me wasting ammo!

Any help appreciated!

 

[ashray]

my ruger precision rifle 1in 10 twist 20" barrel: sako 150gr hammer heads 2468fps and nosler 150gr b/t 2640 fps both chronographed and quite surprising but both very effective, just for information, s+b 180gr sierra game king bullet, box states 2840 fps ,from my rifle 2325 fps!! have a look at p-max internal ballistics it normally accurate.

 

[sir-lamp-alot]

Sakos web site are giving 2805 fps for that bullet not sure what length barrel tho or if its true

 

[Bowland blades]

borrow or buy a chrono and be done with guesswork . barrels vary not just in length as do loads

 

[Hook'N'Bullet]

borrow or buy a chrono and be done with guesswork . barrels vary not just in length as do loads

Yeah I don't know anybody with one. Nor do I want to spend the money on a single use item

 

[Hook'N'Bullet]

my ruger precision rifle 1in 10 twist 20" barrel: sako 150gr hammer heads 2468fps and nosler 150gr b/t 2640 fps both chronographed and quite surprising but both very effective, just for information, s+b 180gr sierra game king bullet, box states 2840 fps ,from my rifle 2325 fps!! have a look at p-max internal ballistics it normally accurate.

That's very interesting. A lot slower than I had anticipated. I was expecting somewhere around 2650ish

My Tikka is a 1:11 twist

 

[NoIDeer]

Yeah I don't know anybody with one. Nor do I want to spend the money on a single use item

Edinburgh Rifles were advertising renting chronographs out a while back?

 

[jb1]

Could you guesstimate by measuring drops from 2 distances ie 100yds to 200yds ?

 

[Foxyboy43]

Try this - used to be in their ammo boxes. Add or subtract 25 fps per inch of barrel.

 

[Bowland blades]

Yeah I don't know anybody with one. Nor do I want to spend the money on a single use item

there is always someone when you ask about . Far from a single use item , i have had mine over 20 years and its very useful for load development looking for those single digit spreads , think it must have saved me its cost just finding out that sometimes more powder only costs more or gives a worse deviation . Do some primers work better etc etc .
What is says in the load manual isnt always what you get in your gun etc etc etc .

 

[Hook'N'Bullet]

there is always someone when you ask about . Far from a single use item , i have had mine over 20 years and its very useful for load development looking for those single digit spreads , think it must have saved me its cost just finding out that sometimes more powder only costs more or gives a worse deviation . Do some primers work better etc etc .
What is says in the load manual isnt always what you get in your gun etc etc etc .

That's all very good but I don't reload and its not an option here in Ireland. Thanks for your input anyway!

 

[Hook'N'Bullet]

Could you guesstimate by measuring drops from 2 distances ie 100yds to 200yds ?

Yeah that's what I'll probably end up doing

 

[Hook'N'Bullet]

Sakos web site are giving 2805 fps for that bullet not sure what length barrel tho or if its true

they're usually put through a 24" barrel.

So if I do the maths - with 25fps loss per inch as mentioned here that works out at 2705fps.

However, I've also heard it can be 50 fps per inch lost so that works out at 2605fps.

I'm not looking for pinpoint accuracy, just something to get on paper

 

[jb1]

Yeah that's what I'll probably end up doing

(Granny and egg sucking here)
But if you can stretch out, further the better.

 

[Hook'N'Bullet]

(Granny and egg sucking here)
But if you can stretch out, further the better.

Ah sure look, I can barely get a place to stretch 200 so we will see

 

[MarinePMI]

Yeah that's what I'll probably end up doing

Enter your best guess of velocity and zero at 100 yds.

Then shoot as far as you can (up to 600). 300yds would be better than 200yds.

Then true the BC calculator by adjusting the velocity of the round until the calculator is giving the correct dope for your long shot group to be POA=POI. Do NOT adjust the BC.

Done.

It's pretty simple, especially for hunting ranges.

A chrono is always better though, and a Magnetospeed Sportsman model is something worth having IMHO, even for those just hunting with factory ammo.

 

[Foxyboy43]

they're usually put through a 24" barrel.

So if I do the maths - with 25fps loss per inch as mentioned here that works out at 2705fps.

However, I've also heard it can be 50 fps per inch lost so that works out at 2605fps.

I'm not looking for pinpoint accuracy, just something to get on paper
[/QUOTE
It is 25fps per inch.

 

[Heym SR20]

Just do it the old fashioned way. Zero 4cm high at 100m. Check the zero at 200m. It will be just a few cm low so you will be pretty much point and shoot to 200m. Then check your point of impact at 250, 300, 350 etc either noting down your drops, or use the turret to zero at each range and noting the number of clicks at each range.

 

[Foxyboy43]

Look at the Sako table - Zeroed 0.7cm high at 50m is 6cms low at 200 - pretty much point and shoot at reds.

 

[Edinburgh Rifles]

I know it's a bit of a long shot but could anybody tell me the rough speed of factory Sakos 150gr Super Hammerheads in .308 out of a 20 inch barrel?

OR

Factory Federal Premiums Nosler BTips in same weight/set up

Or better yet, if somebody has a chrony figure for this set up?

Without owning a chrony, I'm trying to get a BC calculator running and they're advertised at 2805 fps but that definitely won't be an accurate number for my 20 inch barrel. I know the general rule is 50fps per inch (test barrel 24inch ?) But I've read other say it's as low at 25fps per inch.

If this fails, I'll have to shoot at zero, shoot at 200 and mess around with speed in the app to match the drop etc. It would be handy if somebody had the same set up and save me wasting ammo!

Any help appreciated!

Even of they do have data your rifle will be different
You’ll be getting 2650-2675fps from them from memory

Only your rifle can tell you

Shoot one at 100 and 5 at 300m
Take an average from the group size and extrapolate