Man that would be tough with a 147 they are long.

With a 24", 1:8.5, I've got a 140 gr coming out at 2780 fps, per trued DOPE.

7 grains more bullet, but 2" more barrel, I thought I could get there.

That's a big claim, but I will run the numbers at that speed, and see what I see. I bet the wind drift does not change. If we were looking at 1/4 MOA, it might, but I'm looking at Mil, of course.

I doubt it will make much difference and not sure I would push it that hard but would be interesting to see ofcourse I could run the #s to see but currently legally blind in one eye has vision screwed up and reading this forum is about it for me with it 200% enlarged

OK here is my data run @ 500ft DA for both 10 mph 3 O'clock wind

Litz published BC for the 147's is .335 G7. Run them at 2780 fps

131's in the correct twist barrel (1:7-1:7.25) BC is .340+ G7 (the published .330 is out of a 1:7.75" @ 2940 fps) so I just ran it at .340 (in the SHOOTER app. I use .360 G7 for everything to line up out to 1600y, .350 G7 in the AB Kestrel) and @3040 fps (yes, it will run 3060 fps with H4350)


<147 v. 131>

Elevation (Mils)

500y 2.7 v. 2.1
800y 5.6 v. 4.5
1000y 8.1 v. 6.5
1200y 11.0 v. 8.8
1400y 14.6 v. 11.6

Wind in mils (10 mph 3 O'clock)

500y 0.7 v. 0.6
800y 1.3 v. 1.0
1000y 1.7 v. 1.3
1200y 2.2 v. 1.7
1400y 2.8 v. 2.1

Retained velocity (FPS)

500y 2134 v. 2370
800y 1792 v. 2012
1000y 1579 v. 1790
1200y 1378 v. 1581
1400y 1193 v. 1383


Energy on target (ft-lb)

500y 1487 v. 1634
800y 1048 v. 1177
1000y 814 v. 932
1200y 620 v. 727
1400y 464 v. 556

Time of Flight (seconds)

500y 0.616 v. 0.559
800y 1.076 v. 0.971
1000y 1.432 v. 1.287
1200y 1.839 v. 1.643
1400y 2.307 v. 2.049

There isn't at .264 bullet that can keep up with the 131's out of the same parent case. The initial velocity and BC make up for the mass difference in all categories, while having less recoil.

Hornady is publishing the 147 gr at .351 G-7

Litz does not agree?

Nope, Litz's testing came out to be .335 G7

Matter of fact Hornady doesn’t ether. They list 3 BC numbers for their ELD bullets. Mach 1.75, Mach 2.0 and Mach 2.25 data. They print the 2.25 data on the box bc... well it looks better but doesn’t hold true to distance.

Here is a good read up on their site along with their numbers: https://www.hornady.com/support/ballistic-coefficient

I had Hornady on the phone one day about some slow factory ammo, one lot I had was running 200fps slower than two other lots.

After discussing that I ask about a couple of their listed BC values, one they answered the other the 3 different guys I talked to really had no idea. They only had G1 BC for the 750gr 50cal A-Max and I ask about G7 to which they apparently did not have. I said your ballistics program cannot handle the published BC of 1.015 it chokes and pukes on it.

Thank you, what muzzle velocity do think jacket integrity is compromised, and at what impact velocity do you this is maximum for hunting?

Thank you.

This changes things.

Bobo, are you thinking about a new barrel for the 257 WBY

Velocity has less to do with jacket integrity than RPM They have proven to hold up well through 10 rounds strings up to 315K RPM and have been shot up to 340k RPM successfully (customer reported but very slow strings of fire without the barrel getting hot) although I wouldn't suggest trying it.

If you follow our recommendations there won't be an issue at any velocity.
1:7 up to 3075 fps
1:7.25 up to 3150 fps
1:7.75 up to 3350 fps
1:8 up to some stupid velocity that kills everything in a 10y radius of impact

We do suggest using the fastest twist possible for your application. These bullets like to spin fast to get their full BC value Which is quite a bit above .330 G7

I can't really answer the second part of your question other than the highest velocity I'm aware of killing a critter was my 25 SAUM running a mild load @ 3175 fps on a coyote @ 300y. Dime sized entry with a half dollar exit hole. Impact velocity would have been 2765 fps 2224 ft-lbs

Eventually, I think she is starting to open up a bit.

Hey Fellas, just letting you know we have some Proof carbon Senderos 1:7.5" ordered and up for pre-sale on our website. These are perfect for 25-06ai through 257wby