257 weatherby 75 grain hammer findings

[Calvin45]

I must say as well this .257 Weatherby cartridge itself goes against everything I've heard regurgitated as "common knowledge". Maybe common knowledge is just cognitive bias that's normalized. Because it's wildly overbore, has a ton of freebore, has a weird curvy shoulder, and headspace's on a belt (I always full resize)….all of those things should be detrimental to accuracy and consistency and make it very finicky and picky.

But it can be made to produce tighter es numbers than my .243 or 270 ever do with barely any work. The first load I just slapped together was with 100 b tips at standard length and a warm charge of 7828 - 3700 fps and under an inch shooting from prone with no real front rest at all. I'll take it.

The second load was a middle of the road load with 100 tsx bullets at just under 3500. Extreme spread of 10 feet per second, no tinkering or fiddling.

I don't get it. But I'll take it!

 

[Capt RB]

The 257 bee I have I was going to pull apart for the action. After shooting it some it now will be a switch barrel. I had 10rnds I loaded up just to make it go bang. 66grn H4831 91/2m with a 117sst loaded to just before the canelure. Didn't chrono
3-9 redfield in redfield jr mount. Holding top of a 12" gong @300yds put all 10 into 2" over an hour shooting 2 and setting it aside.
Calvin45 I have a forstner full length die that I adjusted so I just bump the shoulder about .003 using the method Broz shows in his video. The die out of the box is .005 tension. This may help you with brass life which is spendy as you know

 

[MagnumManiac]

But it can be made to produce tighter es numbers than my .243 or 270 ever do with barely any work

I can tell you why. The longer throat allows a gentle start pressure that rises slower than a standard throat. It also allows more powder for a higher velocity than a normal cartridge design allows.
This gentle transition to the rifling allows a better accuracy potential, contrary to what most believe, and allows a standard deviation that is very uniform…have seen this over the pressure trace with every Weatherby cartridge I have tested, which are the 270 Bee, 300 Bee, 340 Bee and 375 Bee. All but the 375 Bee have .376" throats while the 375 Bee has a custom match grade chamber running a .500" throat, in a 24" barrel, it gets over 3000fps with 250/260g pills, 2950fps with 270's and 2890fps with 300's, way faster than it should be and within max pressure limits. The accuracy is unbelievable, as a H&H, it was excellent anyway, but after re-chambering it shrunk the groups even more.

Cheers.

 

[Calvin45]

I can tell you why. The longer throat allows a gentle start pressure that rises slower than a standard throat. It also allows more powder for a higher velocity than a normal cartridge design allows.
This gentle transition to the rifling allows a better accuracy potential, contrary to what most believe, and allows a standard deviation that is very uniform…have seen this over the pressure trace with every Weatherby cartridge I have tested, which are the 270 Bee, 300 Bee, 340 Bee and 375 Bee. All but the 375 Bee have .376" throats while the 375 Bee has a custom match grade chamber running a .500" throat, in a 24" barrel, it gets over 3000fps with 250/260g pills, 2950fps with 270's and 2890fps with 300's, way faster than it should be and within max pressure limits. The accuracy is unbelievable, as a H&H, it was excellent anyway, but after re-chambering it shrunk the groups even more.

Cheers.

Interesting. I'm certainly not afraid of
The freebore but have never heard anyone claim it helps accuracy haha. Have a friend with a .257 just like mine. He's got his Barnes ttsx seated out so two grooves are visible and the dang thing is barely in the neck haha. "Chasing the lands" but I don't think his gun or loads shoot any better than mine at factory length.

 

[Calvin45]

Hey all just a further update on this load

I am ready for whitetail season!!!

Went to our local gun range yesterday with a friend. I had never actually been there before. Man I had a blast..,literally. I also had never actually shot gongs or steel of any kind before and now I am fully addicted. Holy smokes that was fun!!!!!

Anyway, this load kicks serious butt AND ITS ACCURATE!!!! as some of you know I attained crazy speed with 120 grainers in my 300 Winnie…but they indeed are simply not accurate at all, my .300 rifle doesn't like anything lighter than 180 grains it turns out. Which is fine. That's what it's for anyway.

But this 257 weatherby loves light loads going fast! And the claims about hammer bullets so far have all held up which really surprised me. I'm a skeptic by nature, and whenever anything seems too good to be true it usually is. So far the hammers really are proving to be "true". The final verdict comes in November regarding terminal performance but I have no doubts.

The load was worked up in cooler weather and rl17 is a bit temp sensitive. She was chronographing at 4200 feet per second and exhibited some mild pressure indicators - shiny spot on the case head, some light primer cratering…not a big deal, and should be settled right back to where it was when I developed this load, which is 4150 and notably less pressure indication.

But holy smokes i was so impressed with that rifle, cartridge, and load. The es numbers were all within 10 fps of each other over 5 shots over the chrono. That's mental, at those velocities and in this overbore of a case I'll brag about that haha.

It's accurate too, mor accurate than anything from that rifle so far: well under one inch at 100 yards. And good grief she shoots flat. I don't know what the ballistic calculator says should happen and don't care, I've taken it through it's paces on the gongs to 500 yards which is as far as the range goes. It's more or less dead on at 50, and again at around 400. Definitely less than a foot of drop at 500. A bit high at 200, higher still at 300, about 4-6 inches or so I can't recall exactly.

But this is a bonafide accurate 500 yard hold on hair deer laser. And I feel confident going hunting with it BECAUSE…shooting off a bench is one thing…but I was able to REPEATEDLY make a standing offhand hit on a 8-10 or so inch gong at 500 yards!!!! . I'm high on that for a while now, I'll take credit for that one haha. My friend joked he's not going to take me with him next time after I smoked that gong…I do love the vanguard rifle itself, ergonomically it just fits and feels right. There's a lot of rifles too light or too heavy for me to even think about taking offhand shots at 500 yards let alone nailing them. It's "just right" for me.

@RockyMtnMT, @Muddyboots , @GLTaylor , @ButterBean I know you fellas will enjoy reading about these findings. @Blackdirt Cowboy i beleive it was you who asked me to keep you updated on my findings as this load development played out. Here they are! And if that wasn't you…sorry! Weatherby vanguard stainless synthetic, .257 weatherby magnum, 75 grain hammer bullets (hbn treated but I don't think that matters on these, just for consistencies sake as I treat all my other bullets and the bore too), RL17, non-magnum primers…and yours truly . Man what a winning combo!

 

[Muddyboots]

Ho boy!!!! @WYO300RUM you reading this!!!

 

[Calvin45]

Ho boy!!!! @WYO300RUM you reading this!!!

Ah yes, with 300RUM in his title he must be a fellow speed freak! Bring him in! .

 

[ButterBean]

Hey all just a further update on this load

I am ready for whitetail season!!!

Went to our local gun range yesterday with a friend. I had never actually been there before. Man I had a blast..,literally. I also had never actually shot gongs or steel of any kind before and now I am fully addicted. Holy smokes that was fun!!!!!

Anyway, this load kicks serious butt AND ITS ACCURATE!!!! as some of you know I attained crazy speed with 120 grainers in my 300 Winnie…but they indeed are simply not accurate at all, my .300 rifle doesn't like anything lighter than 180 grains it turns out. Which is fine. That's what it's for anyway.

But this 257 weatherby loves light loads going fast! And the claims about hammer bullets so far have all held up which really surprised me. I'm a skeptic by nature, and whenever anything seems too good to be true it usually is. So far the hammers really are proving to be "true". The final verdict comes in November regarding terminal performance but I have no doubts.

The load was worked up in cooler weather and rl17 is a bit temp sensitive. She was chronographing at 4200 feet per second and exhibited some mild pressure indicators - shiny spot on the case head, some light primer cratering…not a big deal, and should be settled right back to where it was when I developed this load, which is 4150 and notably less pressure indication.

But holy smokes i was so impressed with that rifle, cartridge, and load. The es numbers were all within 10 fps of each other over 5 shots over the chrono. That's mental, at those velocities and in this overbore of a case I'll brag about that haha.

It's accurate too, mor accurate than anything from that rifle so far: well under one inch at 100 yards. And good grief she shoots flat. I don't know what the ballistic calculator says should happen and don't care, I've taken it through it's paces on the gongs to 500 yards which is as far as the range goes. It's more or less dead on at 50, and again at around 400. Definitely less than a foot of drop at 500. A bit high at 200, higher still at 300, about 4-6 inches or so I can't recall exactly.

But this is a bonafide accurate 500 yard hold on hair deer laser. And I feel confident going hunting with it BECAUSE…shooting off a bench is one thing…but I was able to REPEATEDLY make a standing offhand hit on a 8-10 or so inch gong at 500 yards!!!! . I'm high on that for a while now, I'll take credit for that one haha. My friend joked he's not going to take me with him next time after I smoked that gong…I do love the vanguard rifle itself, ergonomically it just fits and feels right. There's a lot of rifles too light or too heavy for me to even think about taking offhand shots at 500 yards let alone nailing them. It's "just right" for me.

@RockyMtnMT, @Muddyboots , @GLTaylor , @ButterBean I know you fellas will enjoy reading about these findings. Weatherby vanguard stainless synthetic, .257 weatherby magnum, 75 grain hammer bullets (hbn treated but I don't think that matters on these, just for consistencies sake as I treat all my other bullets and the bore too), RL17, non-magnum primers…and yours truly . Man what a winning combo!

I'm smiling big