Scratching my head: 7x57 load development

[375 Ruger Fan]

This is the data I got with 160 gr Swift A Frames and H4350. I settled on 45.0 grs.

I also got very good results with Ramshot Big Game powder.

 

[steve white]

Tiny drive bands on NorthFork's let the bullet out the barrel quick, maybe not as much a powder burn or whatnot, but the result is the same as using HBN to lube bullets/bore. That is, the velocity drops--but that means you can up the charge without upping the pressures. Work the loads in that direction. I guess you could use Lee factory crimp dies to delay/make consistent the bullet release.

Also, if you want to see real world 7x57 velocities, get your hands on some RWS loads out of Europe--they'll really make your eyes pop.

 

[steve white]

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?

You are only 37fps off the Nosler Manual listed velocity at identical 44gr. load. Nosler is not known for reducing loading for 7x57.

 

[KoedoePoesPienk]

I wasn’t using S&B brass but saw a massive velocity difference in my 7x57 loads when I switched to a different brand of brass.
PPU had significantly more volume than Norma and Remington brass.
I can’t remember exactly but I think PPU held 6gr more of the same powder than the other two.
I’d compare your S&B brass to other brands.

 

[coreydb]

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

Keep researching the NF bullets and their expansion/impact performance; work up a load you're comfortable with. Yes, some bullets require faster velocity to perform as designed. My info above is the long held minimum general standard velocity/kill shots. Of course there are exceptions when it comes to hand loading using specialized bullets. If I'm off my mark here, apologies. Aa great reference though, is Terminal Ballistics out of New Zealand.

Terminal Ballistics Research
https://www.ballisticstudies.com

 

[RedTag]

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.

This is a very important observation. We can’t have a realistic expectation of what a given load will do in an individual rifle until it is positively tested. My understanding is Speer labs collected posted velocities varying from 400fps under to 300fps over those posted by the SAAMI pressure barrel with the same ammo in different rifles chambered in 7mm Remington Magnum. This is a very substantial difference from one rifle to the next to say the least. I put several different 7RM factory loads through my chronograph and found velocity as far as 200fps below and 200fps above advertised with different loads. The Federal 150gr load advertised at 3,050 coming out at 2,850 giving realistic performance about on par with a .270 or .308 Win. But the Winchester 175gr advertised at 2,850 reading at 3,050 is more akin to .300 Magnum performance. Forget about using that drop data on the back of the box. It simply must be tested and confirmed before being certain.

 

[Rare Breed]

Tiny drive bands on NorthFork's let the bullet out the barrel quick, maybe not as much a powder burn or whatnot, but the result is the same as using HBN to lube bullets/bore. That is, the velocity drops--but that means you can up the charge without upping the pressures. Work the loads in that direction. I guess you could use Lee factory crimp dies to delay/make consistent the bullet release.

Also, if you want to see real world 7x57 velocities, get your hands on some RWS loads out of Europe--they'll really make your eyes pop.

Curious. @rookhawk shows coal of 3.045. My 140 factory ammo was 2.83. Google says 170 grain up to 3.065. I am still working on getting better groupings with my handloads with 175 grain Partitions using the 3.045 coal. My 140 grain are cloverleafs while my 175 are at 1.5 to 2 inches using IMR 4350. Still trying to find the winning formula

 

[Bill J H]

FWIW, when developing loads, I first use an OAL gauge to determine the exact distance to the lands for each projectile.
Next, I back off the lands 5 to 7 thousandths (sometimes the mag dictates my max length cause a cartridge longer than the mag doesn’t help much ).
I then begin loading to attempt to attain my desired velocity and hopefully accuracy. If my velocity is there, I can tweak seating depth and sometimes tighten the accuracy…sometimes not.
This works for me.

 

[Ruraldoc]

First, I have the same rifle in 280 Remington so I know you have a great rifle.

Secondly, I have been handloading 7x57 since 1980 and it is a great hunting cartridge.

My favorite powder for top velocity in 7x57 has always been Winchester 760.

Just work up to 2600 fps in your rifle with a 160 grain bullet and you are good.

Jack O’Connor loaded 160 grain bullets in his wife’s 7x57 at 2600 fps. He reported that she had great results with it, so 160 grain premium bullets like the North Fork are a great choice.

You can reach 2600 fps easily and safely in your rifle. You just have to work up your own data.

 

[steve white]

This is a very important observation. We can’t have a realistic expectation of what a given load will do in an individual rifle until it is positively tested. My understanding is Speer labs collected posted velocities varying from 400fps under to 300fps over those posted by the SAAMI pressure barrel with the same ammo in different rifles chambered in 7mm Remington Magnum. This is a very substantial difference from one rifle to the next to say the least. I put several different 7RM factory loads through my chronograph and found velocity as far as 200fps below and 200fps above advertised with different loads. The Federal 150gr load advertised at 3,050 coming out at 2,850 giving realistic performance about on par with a .270 or .308 Win. But the Winchester 175gr advertised at 2,850 reading at 3,050 is more akin to .300 Magnum performance. Forget about using that drop data on the back of the box. It simply must be tested and confirmed before being certain.

Lots of "blue sky" in the listings on the back of boxes. First time I shot at 400 yds, I was expecting the drop to be as advertised--it was shockingly lower on the target. As you say, the only thing that matters is what THAT load does in YOUR rifle. Once you know, you can make your calculations from there. And without knowing, you cannot accurately dial, use a ballistic reticle or hold over predictably.

 

[steve white]

Curious. @rookhawk shows coal of 3.045. My 140 factory ammo was 2.83. Google says 170 grain up to 3.065. I am still working on getting better groupings with my handloads with 175 grain Partitions using the 3.045 coal. My 140 grain are cloverleafs while my 175 are at 1.5 to 2 inches using IMR 4350. Still trying to find the winning formula

Lots of variables to work on that 175--seating depth, powder type, speed with each powder choice, possibly moon phases, lol. OTOH, if your 140 gr are mono-metal, you possibly don't need a 175 anyway...as long as you have speed.

 

[steve white]

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

I was not aware that a NorthFork was as tough as an A-Frame, food for thought. The 7x57 was created with period cup and core bullets at reasonable speed in mind. It works GREAT within those parameters, with very acceptable kill rates. Trying to edge it up....maybe, but range will be limited more if you use bullets that require more velocity to mushroom--and to what real advantage?

 

[Desperatezulu]

Ran your data through GRT, using the default inputs where not available from you - the most useful/helpful data point would be knowing the average "H2O capacity" of a sample of fired cartridge cases to get a more accurate simulation of your load.

That being said, the initial output from GRT gives a predicted MV of 2400 ft/s - pretty darn close to your measured MV. The peak pressure for this load is calculated at 36000 psi - which is very low and is a likely source of wacky/inconsistent performance. At such low pressure the neck seal in the chamber on firing will be poor (giving very dirty case necks on the outside).

Interestingly, your 44.0gr load theoretically should be very close to an accuracy node.
Your next node up should be around 45.4gr for an MV of 2460ft/s (node 7)
Node 6 is estimated at 48.1gr for an MV of 2612 ft/s and a peak pressure of 49k psi. This is getting closer to the ideal operating conditions IMO.

If possible load up some test loads in +0.5gr increments and give us the MV's and we can finetune from there. The usual caveats apply - the ONLY change from the data you supplied must be the load increments.

I think you'll run out of case capacity before you hit any pressure limits but if/once you hit 2700ft/s, please stop cos you'll be reaching Pmax, aka the red zone. Pmax is only 56500 psi in the old x57, so not too demanding in a modern action - so I wouldn't be too tentative about pushing a load close to this point.

A side note - RL-19 is not really optimal, it's too slow burning. It's likely that you'll have a lot of soot on case necks, in the chamber and a fair amount of muzzle flash from powder burning outside the muzzle.
H4350 would be better, although still not 100% burn - RL-17 would be ideal for this combo

 

[rookhawk]

Ran your data through GRT, using the default inputs where not available from you - the most useful/helpful data point would be knowing the average "H2O capacity" of a sample of fired cartridge cases to get a more accurate simulation of your load.

That being said, the initial output from GRT gives a predicted MV of 2400 ft/s - pretty darn close to your measured MV. The peak pressure for this load is calculated at 36000 psi - which is very low and is a likely source of wacky/inconsistent performance. At such low pressure the neck seal in the chamber on firing will be poor (giving very dirty case necks on the outside).

Interestingly, your 44.0gr load theoretically should be very close to an accuracy node.
Your next node up should be around 45.4gr for an MV of 2460ft/s (node 7)
Node 6 is estimated at 48.1gr for an MV of 2612 ft/s and a peak pressure of 49k psi. This is getting closer to the ideal operating conditions IMO.

If possible load up some test loads in +0.5gr increments and give us the MV's and we can finetune from there. The usual caveats apply - the ONLY change from the data you supplied must be the load increments.

I think you'll run out of case capacity before you hit any pressure limits but if/once you hit 2700ft/s, please stop cos you'll be reaching Pmax, aka the red zone. Pmax is only 56500 psi in the old x57, so not too demanding in a modern action - so I wouldn't be too tentative about pushing a load close to this point.

A side note - RL-19 is not really optimal, it's too slow burning. It's likely that you'll have a lot of soot on case necks, in the chamber and a fair amount of muzzle flash from powder burning outside the muzzle.
H4350 would be better, although still not 100% burn - RL-17 would be ideal for this combo

You're 100% correct on the dirty case necks. I opted start low and work up, but I'll push it up in half grain increments until I think i'm near case capacity. I believe the max loads are compressed loads, not something I wish to do because seating depths can effect things drastically.

Next step, a round of 44.5, 45, 45.5, and 46gr rounds to test for pressure signs. Would you estimate which of the powder volumes I just listed would likely be on an accuracy node? After pressure test, I'd try 5 rounds of your suggested most accurate to see if it corresponds.

 

[Desperatezulu]

The 45.5gr load should be close to a node (45.4gr should be node 7) - case fill is around 95%.
You can probably cut to the chase and test 45.5 and 46.0 gr and see what MV's that gives up and we can re-calculate from there. Or add 46.5 and 47.0gr (which is where the half-node sits at 2546 ft/s)

Even the 48.1gr load is just over 100% case-fill - in my experience, this degree of fill is just fine. It won't affect seating depth unless you have a severe lack of neck tension (in which case you have bigger problems). You might have a little bit of crunch on seating but I would not expect any other issues.

 

[ZG47]

Keep researching the NF bullets and their expansion/impact performance; work up a load you're comfortable with. Yes, some bullets require faster velocity to perform as designed. My info above is the long held minimum general standard velocity/kill shots. Of course there are exceptions when it comes to hand loading using specialized bullets. If I'm off my mark here, apologies. Aa great reference though, is Terminal Ballistics out of New Zealand.
Terminal Ballistics Research
https://www.ballisticstudies.com

I have not used that outfit myself BUT I have never heard any whinging about their data and ... bad news travels quickly, especially in our little nation.

 

[AZDAVE]

Years ago I had a Dakota 10, in 7x57( It was traded as part of a package for my krieghoff 500/416. I do miss that little single.

With it I found I got the best performance and accuracy using H4350 or Ramshot Hunter in the 54-57Kpsi range.

I think the RL-19 might a
Be a bit to slow burning powder. I currently don’t have access to my quick load program. But would someone run the RL-19 with the specs of @rookhawk rifle and see what the percentage of powder burned is.

 

[FlyGuy]

You're 100% correct on the dirty case necks. I opted start low and work up, but I'll push it up in half grain increments until I think i'm near case capacity. I believe the max loads are compressed loads, not something I wish to do because seating depths can effect things drastically.

Next step, a round of 44.5, 45, 45.5, and 46gr rounds to test for pressure signs. Would you estimate which of the powder volumes I just listed would likely be on an accuracy node? After pressure test, I'd try 5 rounds of your suggested most accurate to see if it corresponds.

Also ran a few numbers through GRT with the 160gr NF bullets, but there are a few caveats.

- I set the maximum pressure to 60 000psi for a modern, strong action rifle.
- Case H2O capacity is 59.5gr.
- OAL is 2.990"
- The following powders are ideal for the cartridge volume vs bore diameter.
- All loads have a load density > 90%
- All loads are maximum loads! Drop back 3-4gr and work up slowly.

IMR 4350 @ 45.0gr = 2600fps
VV N150 @ 42.0gr = 2580fps
VV N550 @ 44.6gr = 2665fps
CFE 223 @ 43.8gr = 2638fps
Norma URP @ 45.2gr = 2595fps

RL 19 is way too slow for the 7x57. Half the powder is going out the front of the barrel without being burned. H4350 also doesn't achieve full burn out in a 23" barrel.
Something around 2600fps should be an ideal balance, if the rifle is accurate at that velocity.

 

[steve white]

Also ran a few numbers through GRT with the 160gr NF bullets, but there are a few caveats.

- I set the maximum pressure to 60 000psi for a modern, strong action rifle.
- Case H2O capacity is 59.5gr.
- OAL is 2.990"
- The following powders are ideal for the cartridge volume vs bore diameter.
- All loads have a load density > 90%
- All loads are maximum loads! Drop back 3-4gr and work up slowly.

IMR 4350 @ 45.0gr = 2600fps
VV N150 @ 42.0gr = 2580fps
VV N550 @ 44.6gr = 2665fps
CFE 223 @ 43.8gr = 2638fps
Norma URP @ 45.2gr = 2595fps

RL 19 is way too slow for the 7x57. Half the powder is going out the front of the barrel without being burned. H4350 also doesn't achieve full burn out in a 23" barrel.
Something around 2600fps should be an ideal balance, if the rifle is accurate at that velocity.

I have sometimes gotten good 7x57 loads with IMR 4064, but USUALLY it all comes back around to 3031.

 

[F. Vaccaro]

The 7X57 has been doing a fantastic job with velocities well below 3000fps for over 100yrs. It is still doing it with cup and core bullets. Let's not over think this, a proper zero, accurate load, will reliability take game at 300yds. Even the 175 gr (which is what the 7X57 earned it's reputation with) isn't useless to 300yds. We have a fantastic cartridge here, let's enjoy it!