Scratching my head: 7x57 load development

[rookhawk]

So I had a wonderful evening yesterday sighting in my 7x57 dakota single shot in preparation for a bear hunt. A fellow AH-er let me use his private range and even assisted with transcribing chrono data.

The confusing thing is that I got real-world velocities below the anticipated amounts based on reloading manuals.

I'm using a Northfork 160gr soft. The rifle has a 23" barrel which is similar to the test barrels in the reloading manuals. I'm also using RL-19 powder.

My Results:
44gr of RL19 resulted in 2380fps average

Published loads:
Sierra 5th Edition with 160gr bullet states:
44.2gr =2500fps and max load of 47.4gr at 2700fps

Nosler says starting load of 43.5gr at 2412fps, 44gr at 2517fps, Max Load of 46gr at 2622fps

AlliantPowder.com website and they only list RL-19 for a 160gr Speer SP with a max of 49gr @ 2,570fps

The goal and concern:

I'm not a speed freak, but I did anticipate more velocity/energy from the load I tested. I'm also extra cautious because I'm using Northforks and there is no published load for that specific bullet. I estimated my load was going to produce 2450fps velocities, not 2380fps. I'd like to up the velocity so its a suitable load for Elk and Africa as well.

The question:

Would you recommend I load up a round each of 44.5gr, 45gr, 45.5gr, 46gr and check for pressure signs? 46gr would be the max load cited in the Nosler manual. OR should I go to higher grains of powder in that same ladder based on the Sierra and Alliant data that says 47.4gr-49gr maximums?

 

[FlyGuy]

The Dakota will handle a lot more pressure than the manuals suggest.
Load up your favourite powders in .4gr increments until you get to a compressed load.
Starting at the bottom, shoot a ladder test while watching for pressure signs.
The rifle will tell you where it wants to shoot.
I comfortably run 160gr Nosler AB’s at 2750 with 46.0gr of N550.

That being said... the 7x57 is like the 6.5x55.
They don't need to be pushed hard to kill everything you aim at.

 

[coreydb]

Your load velocity as of now, is definitely adequate for medium size game. That combined with your pounds of pressure caused with impact kills. The lowest velocity for a kill shot is about 1400-1600 fps. There will be more members who'll come on line with more and specific info for you.

 

[rookhawk]

Your load velocity as of now, is definitely adequate for medium size game. That combined with your pounds of pressure caused with impact kills. The lowest velocity for a kill shot is about 1400-1600 fps. There will be more members who'll come on line with more and specific info for you.

With the NF bullet being tough, akin to an A-Frame I had thought I would need more energy to ensure proper expansion.

 

[MacJenkins]

So I did quickload you at 2426 FPS with the 44 charge and only at 40,011 PSI. I am with the others. Falling blocks, K-95 etc i persobally run hotter.

I don't know your OAL but at 47 grains you are 100% fill at 47 grains. 2593 FPS and 48,576 PSI. I usually run my singleshots in the 55K psi range and look for signs of pressure getting there.

I'm guessing you might run out of room with RL-19 depending how fast you want to push it.

 

[rookhawk]

Current trajectory at 2380 on the left. Trajectory at 2550 on the right. It appears that for anything inside of 300 yards, I'd need a bit more speed. (but not a max load)

 

[MacJenkins]

With the NF bullet being tough, akin to an A-Frame I had thought I would need more energy to ensure proper expansion.

I have found Northforks to run a good bit lower speeds and pressure than other similar bullets with the same charge. I would think it is because of there small thin driving bands.

I texted you the Quickload data.

 

[jnmullins]

My 7x57 Sauer M98 also runs a bit slower than expected book velocities. In other cartridges, I have done as you suggest and loaded up a single round at half grain intervals and chronograph them until I get to approximately my expected velocity. If you have a bullet puller, I would recommend going all the way up to 49gr, but not exceeding 2700 fps. I stopped at 2600 using H4350 behind 160gr Norma Tipstrikes because it groups well there

 

[rookhawk]

So I did quickload you at 2426 FPS with the 44 charge and only at 40,011 PSI. I am with the others. Falling blocks, K-95 etc i persobally run hotter.

I don't know your OAL but at 47 grains you are 100% fill at 47 grains. 2593 FPS and 48,576 PSI. I usually run my singleshots in the 55K psi range and look for signs of pressure getting there.

I'm guessing you might run out of room with RL-19 depending how fast you want to push it.

My COAL and other facts:

 

[MacJenkins]

My COAL and other facts:

View attachment 712868

I ran your slightly shorter OAL and it changed the velocity to roughly 10-13 fps more accross all charges.

 

[Wyatt Smith]

I would increase as planned. The solid shank of the north fork will not deform as much as a lead cored bullet. (Well a standard one anyway) the small drive bands also help keep pressure lower.

 

[wswolf]

7x57 chambers vary greatly in throat length so velocities vary greatly in individual rifles.
7mm-08 and 7x57 have virtually identical case capacity and therefore can be loaded to the same velocity with appropriate powders.

I took John Barsness' advice and loaded to Hodgdon's published 7mm-80 velocities with great success. Powders in the 4350-ish range work just fine. StaBall 6.5 is outstanding in every way.

 

[MacJenkins]

7x57 chambers vary greatly in throat length so velocities vary greatly in individual rifles.
7mm-08 and 7x57 have virtually identical case capacity and therefore can be loaded to the same velocity with appropriate powders.

I took John Barsness' advice and loaded to Hodgdon's published 7mm-80 velocities with great success. Powders in the 4350-ish range work just fine. StaBall 6.5 is outstanding in every way.

I agree, I think RL19 might be a tad slow depending on how fast you want to push it. 4350's, 4451, RL 16, 17, N150 etc would be my next try if you can't fit enough RL19.

 

[rookhawk]

Could be. I'll try with a ladder stopping at 46gr or whenever there are pressure signs. I'm not greedy. 2500ish FPS would make it viable out to 275 yards, in my entire life I've only hunted two animals passed those distances.

 

[AckleyHunter]

Are you sure your chrono is setup up correctly? Run a factory load or another rifle as a contol.

 

[rookhawk]

Are you sure your chrono is setup up correctly? Run a factory load or another rifle as a contol.

It was very consistent over 13 shots. It was the new Garmin unit that is known for reliability.

 

[PanhandlinPat]

I ended up using RL16 in my 7x57s, both Remington 700 classics. Couldn’t get enough of the slower powders in the case. This nosler data shows 47.5 as the max.

 

[AckleyHunter]

It was very consistent over 13 shots. It was the new Garmin unit that is known for reliability.

If it was too far from the barrel or not square to the target it would be consistent, but consistently wrong. But, I have one of those and as long as it is no further than 4 inches from the barrel center, or 10 inches from the muzzle it works well. I did have it about 5 inches from the center once and was getting about 100 fps lower readings.

 

[Ray B]

About 40 years ago I ran a test with the 8 30-06s that I had at the time. Using identical loads which as I recall was 56-58 grains of IMR 4350 and 180 grain Speer spitzers I got a variety of results. Using a friends Oehler chronograph there was a variation of more than 100 fps muzzle velocity. One point of interest was that after the firings I kept the cases sorted for each rifle, then without sizing, put each case in the various rifles. there did seem to be a correlation- the tightest chambers had the highest velocities- the largest chambers had the lowest. Additionally, checking the leade, a similar effect was noted- longer leades equaled less velocity. The upside shown by additional testing was that the larger chambers/ longer leades also allowed for increased powder charges that resulted in velocities that matched or exceeded the tight chambers.

 

[Bob Nelson 35Whelen]

So I had a wonderful evening yesterday sighting in my 7x57 dakota single shot in preparation for a bear hunt. A fellow AH-er let me use his private range and even assisted with transcribing chrono data.

The confusing thing is that I got real-world velocities below the anticipated amounts based on reloading manuals.

I'm using a Northfork 160gr soft. The rifle has a 23" barrel which is similar to the test barrels in the reloading manuals. I'm also using RL-19 powder.

My Results:
44gr of RL19 resulted in 2380fps average

Published loads:
Sierra 5th Edition with 160gr bullet states:
44.2gr =2500fps and max load of 47.4gr at 2700fps

Nosler says starting load of 43.5gr at 2412fps, 44gr at 2517fps, Max Load of 46gr at 2622fps

AlliantPowder.com website and they only list RL-19 for a 160gr Speer SP with a max of 49gr @ 2,570fps

The goal and concern:

I'm not a speed freak, but I did anticipate more velocity/energy from the load I tested. I'm also extra cautious because I'm using Northforks and there is no published load for that specific bullet. I estimated my load was going to produce 2450fps velocities, not 2380fps. I'd like to up the velocity so its a suitable load for Elk and Africa as well.

The question:

Would you recommend I load up a round each of 44.5gr, 45gr, 45.5gr, 46gr and check for pressure signs? 46gr would be the max load cited in the Nosler manual. OR should I go to higher grains of powder in that same ladder based on the Sierra and Alliant data that says 47.4gr-49gr maximums?

@rookhawk
Every rifle is a law unto itself.
When working up loads I load one round of each weight of powder from min to max..
If no pressure signs at max I will start there . Conversely if I get pressure signs I go down at least 2 grains and start there.
Not only does it depend on the rifle I have found it depends on case as well. Some cases will hold more some less.
Using your chronograph work up to the velocity you want PROVIDED THERE ARE NO PRESSURE SIGNS.
A change of powder may also be needed or those bullets just and your rifles just won't give you what you need
Bob