Anyone mind finding this velocity?

[Rock Knocker]

I've got a small local competition next weekend and Im using a new promising load but I have only been able to shoot it at 300 yards.

I was hoping someone could run the load in some of that fancy sotfware and give some some sort of ball park velocity to start with.

The load: 260 Ackley
47.76gr H4831
140gr Hornady A-Max
CCR BR-2 primers
30" 1-8" barrel

I wont bother trying to look 9 days into the future for the forcast but temps will probly be around the low 20 degrees F (These are some tough old dudes that dont want to sit around all winter!)

Let me know if there is any other information I can provide. Thank you a lot for any help.

 

[GermanS1]

Hair computer and some old experience with the .260 says 2800 fps. Rough guess, but probably close.

 

[Forum Boss]

Provide the case capacity (in grains of water), and the Cartridge Overall Length (with bullet seated, case rim to bullet tip) and I can run Quickload. With a guessed capacity of 56.5 gr H20, 2.800" COAL, Quickload says 2923 fps.

Please understand, however, that such number can change considerably if my GUESSES about your case capacity and COAL are wrong!! And even when I get the accurate measurements, QL can still be off by 100 fps or more.

 

[Rock Knocker]

Ok the H2O capacity is 58.28gr. and the COAL is 2.879"

Thanks for the help.

 

[Forum Boss]

Ok the H2O capacity is 58.28gr. and the COAL is 2.879"

Thanks for the help.

With those numbers, QuickLoad predicts 2842 fps at 48830 psi. If your load is in the lands (bullet seated into rifling), QuickLoad predicts 2876 fps at 51907 psi, assuming a 6000 psi start pressure (I used this number for in-the-lands seating as it seems to be more accurate than the higher number recommended).

Strongly suggest you borrow a chronograph. As noted, QuickLoad could be off by 100 fps.

 

[MrMajestic]

Hey German, what OS you running in that hair computer? ;D Good guess for an engineer!

 

[alf]

For comparison's sake,

In my 22" Rock, 47 grains gave me 2690 with 140 VLD's. I couldn't get any more in with an OAL of 2.80" for mag length.

In my 26" factory VLS, 48 grains gave 2818, seated long for a square mark at 2.910" with 142's.

Both loads were with moly plated bullets.

I'd say the Boss's numbers at 2875 is pretty close with bare bullets and a 30" tube.

 

[Rock Knocker]

Excellent thank for all the help guys.

 

[ShaneG.]

In my 260AI with 140 Amax's and 4831sc I run 48.0g and get 2880fps out of a CBI 28" 8twist.