257 Wby range day - 115 NBT - any feedback?

[Dr. Vette]

Today I went out to the range with the 257 ULW Weatherby. This rifle shoots Sub-MOA with factory 115 NBT ammo, so one would think that I could also do that with reloads, right?

Distance of targets is 200 yards (not 100).

Weatherby brass, previously used in this rifle, annealed, body sized and shoulder bumped .002 with Redding die then neck sized with 257 Lee collet die. This shows a lot less variation than using a Redding bushing die from what I have seen. Fed 215M primer, IMR 7828SSC powder.

Targets are at 67.0 (upper left), 67.5 (upper middle), 68.0 (upper right) and 68.5 grains (lower left). Per my ladder testing last week the groups get larger when using less than this or more than this, and 69.5 gives a stiff bolt lift. So, no need going up or down on charges.

Cartridge OAL (3.231) is longer than factory (3.142-146; 3.160 other box) and set at just under magazine length. I found a lot of variation in the 3 boxes of factory ammo that I have, so for last week and this week decided to try the longest COAL possible and go from there.

From what I can see it appears that my load is likely around the 68.5 gr area, and that I should try shortening the COAL back towards the factory length to find the sweet spot. I knew going into this that it was probably at 68.0 or so, and it may not hurt to try both at shorter COALs and see what I get.

So what feedback do any of you have regarding today's test?

Patrick

 

[Sas874runner]

I would venture to guess 68.5 gr and seat deeper .010 at a time. With weatherby free bore the.bullet may need to jump more. Which is very non typical of a cup and core bullet but being that factory is shorter and shoots well I would go that route

 

[Dr. Vette]

Given that mine is 3.231 and factory is as short as 3.142, I was thinking of following Berger's guidelines and trying 3.20, 3.17 and 3.14 to start. I can then fine tune from there.

I use the Redding competition seater and measure to the ogive, but that seater is so accurate it's unbelievable. Every load measures within 0.001 or less without trying; its really within my limits of error.

 

[kraky]

I think you are 100% correct going deeper w/the seating.
I have a 300 wby ul and I half shot out the barrel w/tons of different slow powders and many applicable bullets.
All my other wby shot great near clip length but this thing was doing 5-6" groups at 200.

As soon as I seated deep....like ogive just out of the case mouth....the darn thing went moa and under. Those long thin barrels are crazy tuning forks I guess.
Mine was one of the early American made ul's....those early ones didnt have a good reputation in my area.

 

[dubyam]

I'll add my corroboration to your idea to go to a shorter COL. I like your "Berger Method" idea, as I believe you'll find the best COL somewhere in the shorter end of that spectrum. Two together and one out is almost always helped by shortening.

What are your velocities for the 68.5gr load?

 

[DrMike]

You are absolutely correct in focusing on 68.5 grain as the appropriate charge. For testing seating depth, you can afford to go in 0.030 to 0.040 inch increments to find the sweet spot. I believe you are on the right track.

 

[JD338]

As already stated, you need to seat the bullets deeper. Did you clock your loads?

JD338

 

[Dr. Vette]

67.0 3333/3307/3335

67.5 3369/3369/3339

68.0 ? / 3331 / ?

68.5 3366/3376/3385

Errors at 68.0 as the chrono does an error when the lane next to me shoots.

 

[nvbroncrider]

Sweet shorten the 68.5 up and you will be in business.

 

[SJB358]

I will go with all the others. Reshoot your current load at 68.5 and start shortening them down .025/.030" in interval. I am betting it'll really show something as you continue seating them deeper. Your pretty close at current load with just one flier outta that group, so I would imagine your one range session away from having a really good load.

That is screaming as well. RL25 was running the 120 PT's around the same speeds and I was really impressed with that 257W.

Thank you for posting the targets. It is great to see a load come together.

 

[Dr. Vette]

That is screaming as well.

Up to 100fps faster with higher charges but I shot one 69.5 yesterday, lifted the bolt and said Nope - too stiff on that one. No overpressure signs noted last week at 69.0 and below; ambient temp both weeks about the same.

 

[SJB358]

I can't see nearly 3300+ being awful at all! That is a screamer. I really have a bug about getting a 257 Wby after working with my little brothers rifle. It was fun...

 

[Darkhorse]

I wouldn't kick the 68. load out of the running yet. It has a good shape to the group. I would try both with the same COL's until one outshines the other and repeats.

 

[rodell]

My experience has been to load up up close to the factory length and let them run. Longer has rarely helped me.

How much cooling time did you allow between shots? My ULW's get a little whippy after 3 in fairly rapid succession. Did you shoot these round-robin or all charges at once?

 

[Dr. Vette]

My experience has been to load up up close to the factory length and let them run. Longer has rarely helped me.

How much cooling time did you allow between shots? My ULW's get a little whippy after 3 in fairly rapid succession. Did you shoot these round-robin or all charges at once?

Round robin, 3-5 min apart between every shot, doing one of each charge and then starting over again. Yes, it takes a while then to run through them all, but the rifle is never heated up when I shoot. Starting at 34 degrees ambient didn't hurt either.

 

[SJB358]

I think your closer than you think. Can't wait to see the finalized loads.

 

[DrMike]

When I review your velocities, I'd be more inclined to focus on the 67.5 grain load, or even the 67.0 grain load. Your SDs are more consistent, promising a tighter accuracy when you find your node. For 30 fps, I wouldn't consider the expenditure of an additional grain or grain and a half of propellant to be a necessary expenditure. Just my input.

 

[dubyam]

Am I missing something, Doc? I'm getting an SD in single digit for the 68.5gr load (9.5), where I get not quite double that for the 67 and 67.5gr loads (15.6 and 17.3 respectively). Maybe I'm doing my math wrong (wouldn't be the first time) but I checked it in Excel after running it through my stat calculator, and got the same basic result.

I like the 68.5gr load if you're not seeing any pressure signs there, Patrick. If you're getting pressure signs, it's time to reshoot the highest charge without pressure signs and figure from there.

 

[Dr. Vette]

Dub,

Note that the Beta Master Chrony isn't always the pinnacle of accuracy, especially as the sun rises in the sky. This is more than internet conjecture, I've proven it to myself on a day when the sun showed up halfway through the morning. The skyscreens have their limit...

But yes, what you note seems correct. The 69.5 has a sticky bolt, but 69.0 and the above noted 68.5 were fine. My plan is to adjusts depth on the 68.5 and shoot again.

 

[dubyam]

I surely understand the limits of my BMC. But considering all loads were shot over the same BMC, in roughly the same conditions, the error should be universal enough to maintain comparability, right? I'm geeking statistics now. Sometimes I think I should have been a math major.