257 Weatherby Mag guidance needed

[Kaldor]

OK, back to the drawing board.

Ran thru my initial test loads, 67.5 seemed to be the most promising, 2 @ about .600" at 100 yards, then a flier about 1" to the right. Flier to be expected in a really light barrel as the gun heats up really fast. Im only worried about cold bore accuracy with this gun anyway, as you very seldom take more than 2 shots at an animal. Normal course of fire for this gun is 3 shots, about a minute apart, let the gun cool for 15 minutes before I shoot the next string.

Sorry about the cut up post here guys, THR is having issues with anything that I post that has any length.... Arggg

 

[Kaldor]

Loaded 2 more 3 shot test loads. Weather was about 10 degree warmer, but I keep the ammo cool, and Im in the shade.

Wanted to test rifle and scope, I shot a 3 shot group with factory ammo, 2 shots at .400", then a 3rd about 3/4" high. However the 67.5gr 3 shot groups that had shot well before was all over the place, as in a 6" triangle shaped group

 

[Kaldor]

I have honestly never shot this poorly, and my hand loads have never done this poorly in any rifle, ever. I have thought that the bullet weight might be a little high, but the gun is shooting 117's great, so that discounts that theory as Im shooting 120's. Case prep was the same. Rifle cant be too dirty or scope off as I just shot the factory loads and made a nice group 15 minutes before. The only thing I did different was I hand trickled these up on my 505 instead of my Chargemaster. My Chargemaster and the 505 have always been dead on to each other and I am very meticulous about verification with them.

So, Im stumped. Any ideas? Im tempted to go back and load 3 more at 67.5, but absolutely verify that my Chargemaster is throwing what I think its throwing at for weight.

 

[GooseGestapo]

My .257wm didn’t care for 7828 either.
It prefers 4350 (both H and I), and RL25.

I suggest you try RL25. My rifle was VERY peaky with 7828. My lot # gave excessive pressures with recommended starting loads.
Factory ammo for years was loaded with H4831. Still not a bad choice. Currently I believe it’s loaded with Norma MRP, also an excellent choice.

Also, make sure you square the case mouths, and chamfer them so as to get straight bullet seating and minimal run-out.

 

[Kaldor]

My .257wm didn’t care for 7828 either.
It prefers 4350 (both H and I), and RL25.

I suggest you try RL25. My rifle was VERY peaky with 7828. My lot # gave excessive pressures with recommended starting loads.
Factory ammo for years was loaded with H4831. Still not a bad choice. Currently I believe it’s loaded with Norma MRP, also an excellent choice.

Also, make sure you square the case mouths, and chamfer them so as to get straight bullet seating and minimal run-out.

I read your post and talked with the owner of the rifle. He went in at the start of this project and bought 8# of the 7828, so Id like to get it running if I can. I warned him about buying in a full 8# jug of powder, in case something like this happens. I also suggested 4831 as an option as we have really good supplies of Hodgdon around here, lesser of others. Wouldnt a 4350 be a little fast for this application, but I guess Hodgdon does have a load chart for it. I wondered about going slower as well, something like Retumbo, but thats not even in a load chart.

Case prep is good. Sized, trimmed on Lyman hand trimmer, SSTL tumbled, chamfered with Lyman chamfer tool. Bullets seat well. I actually do more case prep for my buddys stuff, than I do my own.

Im going to give it another 3 shot test, possibly play with OAL a bit, and absolutely verify that its not going to work. Ive got almost 8# of 7828 that I have no use for otherwise.

 

[GooseGestapo]

I found that 63.5gr of H4350 under a Hornady 100gr soft point came VERY close to duplication of factory load.

Ok, I went back and reread this thread from the beginning.
You really need to buy or borrow a copy of the Hornady manual.
They used Weatherby brass, Federal 215 primers (both what I use), and seated the Hornady 117’s to 3.215” oal.
Start load is 58.0gr IMR7828, MAXIMUM is 65.2 !!!
2.2gr below your load!

With the Hornady 120gr, Max w/7828 is 62.3gr.

This closely matches my experience with 7828.
According to my recorded data 72.0gr of 7828 (Lyman #48 lists 73.0max), I got 3,810fps w/cratered primers, and stiff extraction. TOO HOT!!!
I got nominal results at 69.0gr, which is exactly what Speer lists as maximum with the 100gr bullet.
Speer lists 64.0gr 7828 as max with 120gr. They also used the CCI250primer and FEDERAL brass, which holds less powder (lower capacity) than the Weatherby cases.
This may explain your accuracy issues. As the gun heats up, so will ammo after it’s chambered in the gun, raising velocities and pressures. This will play havoc on accuracy.

Wait 2mi between shots, waiting to chamber next round. 5min between groups. Shot 3-shoot groups. It’s a hunting rifle, not a target rifle.
Clean bore with Montana Extreame Copper remover.
Good luck!

 

[Kaldor]

I found that 63.5gr of H4350 under a Hornady 100gr soft point came VERY close to duplication of factory load.

Ok, I went back and reread this thread from the beginning.
You really need to buy or borrow a copy of the Hornady manual.
They used Weatherby brass, Federal 215 primers (both what I use), and seated the Hornady 117’s to 3.215” oal.
Start load is 58.0gr IMR7828, MAXIMUM is 65.2 !!!
2.2gr below your load!

With the Hornady 120gr, Max w/7828 is 62.3gr.

This closely matches my experience with 7828.
According to my recorded data 72.0gr of 7828 (Lyman #48 lists 73.0max), I got 3,810fps w/cratered primers, and stiff extraction. TOO HOT!!!
I got nominal results at 69.0gr, which is exactly what Speer lists as maximum with the 100gr bullet.
Speer lists 64.0gr 7828 as max with 120gr. They also used the CCI250primer and FEDERAL brass, which holds less powder (lower capacity) than the Weatherby cases.
This may explain your accuracy issues. As the gun heats up, so will ammo after it’s chambered in the gun, raising velocities and pressures. This will play havoc on accuracy.

Wait 2mi between shots, waiting to chamber next round. 5min between groups. Shot 3-shoot groups. It’s a hunting rifle, not a target rifle.
Clean bore with Montana Extreame Copper remover.
Good luck!

I have the horribly lawyered down Hornady 9th that Ive found to be almost completely useless.

Im running off the Hodgdon data from their website, 69gr max, Weatherby case. I think my Lyman 49th gives the same max load, but Id have to check. I shot the gun up the 69.5gr of 7828 in my first pass with zero pressure signs on the primers, and the bolt lift was just as easy as factory ammo, but accuracy was bad. At 67.5gr the recoil is very manageable, bolt lift is easy, and zero pressure signs.

Ill verify my load data tonight a sec

 

[Kaldor]

Ok here I go again.

Resized, trimmed, deburred, primed, double scaled every powder charge, seated at exactly 3.20"



If we don't get any results on this, it will be either H4831 or H4350 that we try. Let's hope it works out without going that way.

 

[CptnAwesome]

My 257Wby likes IMR7828, tried about every load with 7828 in my 300Wby with terrible results. It loves H4831 though. I've read both of those powders do well in Weatherby calibers. So maybe try that one if you can't get the 7828 to shoot good.

 

[GooseGestapo]

I think the issue I have is the particular lot number of IMR7828.
I was looking to work up a load to roughly the equivalent of a heavy .30/06 to light .300winmag for my .300RUM. 180gr Hornady Interlock flat-base bullet.
Extruded powders typically ignite easier/better than spherical, so I tried 82.0gr of IMR7828. (81.0 start, 86.5 max for 3,069fps; per Hodgdon.)
Instead of the expected 2,900-3,000fps, I got 3,200. Excellent accuracy, but accompanying recoil, too. Admittedly, the Hodgdon data is from a 24”bbl and my rifle wears a 26”bbl. But it was a surprise, still.

 

[Kaldor]

Well Im off to the store to get some H4831 if they have it. I hate to give up on the 7828 because my buddy bought in at 8# of the stuff. Right now its good for lawn fertilizer as far as Im concerned.

Right now my reloads are shooting 8" shot groups which is completely unacceptable. I know this rifle is a shooter, .750" 3 shot groups are the norm with factory ammo, Ive even had a couple .500". Even my just completely winging it wild a_s guesses shoot better than this.

 

[CptnAwesome]

8" group? Is that at 100yds? It seems like there could new more wrong than powder of its shooting 8" groups.

Is everything tight on the rifle/scope?

 

[Kaldor]

8" group? Is that at 100yds? It seems like there could new more wrong than powder of its shooting 8" groups.

Is everything tight on the rifle/scope?

Yup, gun shoots 117gr RN factory ammo like a champ. Here's a group I shot literally 6 shots before. 1/2" on the first 2, 3rd shot a little high as the gun warms up.



All groups are shot at 100 yards.

I'm absolutely baffled. The only thing I can think is that this gun just does not like 120gr bullets which is causing this pattern instead of group. So being that the owner is so pot vested in the 7828 powder, I think we are going to drop down to some lighter bullets, say 110 grain.

 

[Blue68f100]

Have you determined what your bullet jump is to lands? And have you compared them to what the factory 117's are?

Weatherby's in general like a long jump.

 

[Kaldor]

Have you determined what your bullet jump is to lands? And have you compared them to what the factory 117's are?

Weatherby's in general like a long jump.

Factory 117s that this gun likes are RNs. Good news is, I found some at a local shop, and they have 4 more boxes on the shelf. So Ill play around with these, see if I can duplicate the factory ammo I have on hand, and if it doesnt work out, the box of bullets as only $22. If they work, I call them and they set them aside for me. And then Im done with this adventure. The OAL on the 117 RNs is very short, like 3.00", maybe less.

And this definitely is a Weatherby barrel, very long leade. You wouldnt be able to reach it, and the guy before me that reloaded for it tried, and got massive pressure signs really early. Im loading the Nosler 120s at 3.20" as Nosler recommends. Used a combination of Nosler, Lyman, and Hodgdon data, and all maxes are right around 69gr with that bullet and 7828.

 

[Blue68f100]

If you have one of these ( https://www.midwayusa.com/product/746974/ptg-bullet-comparator-22-24-25-26-28-30-calibers ) you can determine the difference between bullets, ogive. And not have to actually measure the bullet jump. I knew you were not going to reach the lands and still have enough of the bullet in the neck to hold it. The reason I asked if you ever determine the difference between the bullet profiles.

 

[Kaldor]

If you have one of these ( https://www.midwayusa.com/product/746974/ptg-bullet-comparator-22-24-25-26-28-30-calibers ) you can determine the difference between bullets, ogive. And not have to actually measure the bullet jump. I knew you were not going to reach the lands and still have enough of the bullet in the neck to hold it. The reason I asked if you ever determine the difference between the bullet profiles.

I have not done any comparator measurements. I do have all the bushings for my Hornady tool, I just didn't use them in this case because it's not feasible to try and reach the lands on this rifle.

I think these 117s will be the ticket. A big fat stable projectile should be good to go I'm hoping. I'll build up a handful of test loads and go shoot them next weekend.

 

[GooseGestapo]

One thing will explain why the gun is spraying the 120’s but not the 117 RN’s.

It’s an early gun with a 1/12” twist barrel.
Later guns have a 1/10” twist.
Weatherby still loads the 117gr Hornady RN load for just this reason. It also explains why Roy’s favorite bullet was the 87gr Hornady.

I suggest you check the twist rate of the barrel...
If it’s a 1/12”, try the 110gr FTX. The 110gr SST or Accubond will likely be a bust too.

 

[Kaldor]

One thing will explain why the gun is spraying the 120’s but not the 117 RN’s.

It’s an early gun with a 1/12” twist barrel.
Later guns have a 1/10” twist.
Weatherby still loads the 117gr Hornady RN load for just this reason. It also explains why Roy’s favorite bullet was the 87gr Hornady.

I suggest you check the twist rate of the barrel...
If it’s a 1/12”, try the 110gr FTX. The 110gr SST or Accubond will likely be a bust too.

I've considered pulling the action from the gun so I can verify twist rate, but I'll be honest, I'm a little bit chicken s--t to do it. It's just too nice of a rifle to chance screwing something up. And it's not mine, so it would be twice as bad.

Hodgon lists 70gr as max so with the 117 Hornady RN I'm going to start at 67gr of 7828, 67.5, 68, 68.5, & 69. I've shot this rifle at 69.5 & 70gr and it's painful. I'm betting the load will fall at 68gr.

 

[Blue68f100]

No need to pull the action to check twist rate. Use a tight fitting jag/patch and good free spinning cleaning rod. Put a piece of tape on the rod and measure how for far it travels for 1 revolution.

 

[GooseGestapo]

Exactly. Don’t know why you’d pull action to check twist.

 

[Kaldor]

No need to pull the action to check twist rate. Use a tight fitting jag/patch and good free spinning cleaning rod. Put a piece of tape on the rod and measure how for far it travels for 1 revolution.

Exactly. Don’t know why you’d pull action to check twist.

Hah, that is so simple... How did I not think of that? Thanks @Blue68f100

 

[Kaldor]

Barrel is a 12 twist so no bueno on heavy bullets.

Switched to 117gr Hornady RN like the factory ammo uses. Here's the results.



69gr of 7828 SSC @ 3.06" OAL. 3rd shot flew high, but this is better than the factory loads for 1 and 2.

I'll load a few more, verify and set the scope at a 100 yard zero and call this done.

Thanks for all the help.

 

[Blue68f100]

Good to hear your on the right track now.