Modern Loads for Old Cartridges

[gdcpony]

I found an action to turn into a rifle. I'll add this to my arsenal, though it may take a few years to actually find the time and funds to complete. No biggie. However, as I peruse available data for my favorite cartridge, I find it lacking for modern data. I can find plenty for loading to a 96 Mauser, but that leaves a ton of performance to be gained in a 98 action (which has been checked and is cleared for today's "modern" pressures). This problem is two fold for me. I have another 98 barreled for a 257Roberts. I plan to barrel the other action in my beloved 7x57. In looking for modern loads for these rounds I come up short.

The best I can do is extrapolate for the Bob I already load for and slowly worked up to a pet load of 40 grains of Varget behind a 100gr SPBT that delivers sub MOA and shows no pressure signs (THIS IS 2 GRAINS OVER MAX LISTED SO DO NOT USE AS A LOAD UNLESS YOU ARE 110% SURE YOUR RIFLE IS A GOOD 98 OR MODERN RIFLE). I want to move- once I have expended my current (bought on sale) supplies- to load a 90gr Sierra HPBT with H414 as it seems to deliver better velocity with less pressure. I would like to load this to its full potential. I think it would make a nice versatile round.

For the 7x57 I would like to move either a 140 or 150gr pill along with extreme haste. 2700fps is a listed load at 46k cup. I bet a 50k load would best that by a good 150fps with no ill effects. Assuming of course the load will hit the broadside of a barn (always a consideration). That could be carried down range to hit a far 800yd (my best so far) groundhog with authority.

For all the uses I am likely to put either rifle to here in Ohio where it is mostly used on ground hogs and coyotes and only used on deer for population hunts which are very few and far between, there is no problem with loading for velocity. I just want the bullets moving as quickly as I can so long as accuracy is within my specs.

I tend to load for speed and accuracy and will take the heavier load if the accuracy difference is acceptable. A good example is my daughter's .223 which in my hands is an MOA shooter with most loads, but she is not so good. So I load a zippy little 40gr pill that shoots .1" larger groups for me knowing the 200fps difference between it and the most accurate load will help her hit more than the reduced group. The same applies to me in the hunting field with both bow and rifle where the ability to extend a MPBR is more advantageous than tiny little .5 MOA groupings off a steady rest.

Now, before the flaming begins I am in complete understanding that the max load will not always be the most accurate. I also know to watch for the signs that I may be pushing to the limit, and am willing to back off if I see any signs of it. I just know that these rounds were put into many modern rifles and the factory loadings and reloading data available are way too soft. The reasoning for this is sound (I've owned several 95' so I know they still exist), but for those of us who love these "midlength" rounds it puts us out. I am just looking for some loads to modernize them.

 

[gdcpony]

No one?

 

[Jim Watson]

Years ago there used to be regular gunzine articles on overloading the 7x57. We are more cautious now. People actually think the .257 was a wildcat chambered in all manner of junk actions, and hence loaded light by timid ammo companies.

If you could find what Jack O'connor loaded 7mm with for his wife, you would surely have an effective load, even if the numbers did not thrill you.

 

[gdcpony]

I have been told to follow 7-08 data, but that only took one look. It gets the same velocities (slightly higher actually) with less powder and more pressure.
7-08 140gr 46gr H414 2791 49500cup
7x57 140gr 47gr H414 2715 46000cup

I would say that leads to a 7-08, but where's the fun in that? Actually I want a 7x57 Ack, but the budget won't allow for that until the kids are out of the house.

The .257 is spitting 100gr out at 3250 right now, but I am about to change powders and would love to have a published load to work from.

I tend to try for a mid 3k speed. My 243 I could get up to 4250 with a 55gr pill, but 70gr at 3500 was more the ticket. My AR won't get to that (16" barrel) but a 3200 is still respectable. My .257 with 90gr and H414 should do hit 3500 easily (25" barrel) too and carry nicely down range in the wind. The 7x57??? Who knows.

Just looked at a page that gave load densities. 49gr behind a 140gr bullet is 93%. Guess I wouldn't be putting much more in anyways.

 

[Kernel]

7x57 +P doesn't exist. But what if it did?

Hotter loads for the .257 Roberts exist. They’re called “.257 Roberts +P“. It’s an actual SAAMI recognized pressure level. Not a pseudo “P+” of the kind you sometimes see, made up by the small time ammo manufacturers (or handloaders like ourselves). Regular Roberts is rated for 54,000 psi. P+ Bob is 58,000 psi. 4,000 psi higher. Look around and you can find those hotter +P loads in manuals and on web sites.

SAAMI rates the 7x57 at 51,000 psi, lower than some modern cartridges, but not by much. CIP rates the 7mm Mauser a little higher at 57,000 psi. But SAAMI and CIP aren’t exactly equivalent. They measure pressure in slightly different ways. So CIP’s 10.5% higher number doesn’t necessarily mean the engineers at CIP think their 7x57 can be loaded 10.5% hotter.

When working up 7x57 loads in a strong modern action could you go a little hotter? You probably could. But you’d need to work up that load yourself. Sounds like you have a chronograph. Use it and keep it real. 7x57 +P isn’t an officially sanctified cartridge, but say it was. It’s reasonable to assume it would be like the Roberts, 4,000 psi higher than normal 7x57. That makes our made up 7x57 +P a 55,000 psi cartridge. (Still less than the 7-08, which is a 61,000 psi cartridge).

Plugging some of these numbers into my modified Powley Computer, and jiggering the Load Density to produce these pressure levels (51k and 55k) with 140-150 grain bullets, and looking at the change in velocity, I can see the difference between normal 7x57 and our pseudo +P is 100 fps in a 24“ barrel. 50% less than the 150 fps you supposed in your OP.

So, to sum it up. Using the .257 Roberts cartridge as a guide for the pressure levels, and based on calculations from my modified Powley Computer, in a strong action you should be able to work up loads that would safely coax an additional 100 fps out of the 7x57 with 140-150 grain bullets. To do this, I would use powders in the range of H4350 and N150.

With 100 fps as the goal, work up your loads in small increasing increments, follow proper reloading practices, and back off the moment you detect any pressure signs. YMMV, but that's the approach I'd take.

 

[gdcpony]

Hotter loads for the .257 Roberts exist. They’re called “.257 Roberts +P“. It’s an actual SAAMI recognized pressure level. Not a pseudo “P+” of the kind you sometimes see, made up by the small time ammo manufacturers (or handloaders like ourselves). Regular Roberts is rated for 54,000 psi. P+ Bob is 58,000 psi. 4,000 psi higher. Look around and you can find those hotter +P loads in manuals and on web sites.

SAAMI rates the 7x57 at 51,000 psi, lower than some modern cartridges, but not by much. CIP rates the 7mm Mauser a little higher at 57,000 psi. But SAAMI and CIP aren’t exactly equivalent. They measure pressure in slightly different ways. So CIP’s 10.5% higher number doesn’t necessarily mean the engineers at CIP think their 7x57 can be loaded 10.5% hotter.

When working up 7x57 loads in a strong modern action could you go a little hotter? You probably could. But you’d need to work up that load yourself. Sounds like you have a chronograph. Use it and keep it real. 7x57 +P isn’t an officially sanctified cartridge, but say it was. It’s reasonable to assume it would be like the Roberts, 4,000 psi higher than normal 7x57. That makes our made up 7x57 +P a 55,000 psi cartridge. (Still less than the 7-08, which is a 61,000 psi cartridge).

Plugging some of these numbers into my modified Powley Computer, and jiggering the Load Density to produce these pressure levels (51k and 55k) with 140-150 grain bullets, and looking at the change in velocity, I can see the difference between normal 7x57 and our pseudo +P is 100 fps in a 24“ barrel. 50% less than the 150 fps you supposed in your OP.

So, to sum it up. Using the .257 Roberts cartridge as a guide for the pressure levels, and based on calculations from my modified Powley Computer, in a strong action you should be able to work up loads that would safely coax an additional 100 fps out of the 7x57 with 140-150 grain bullets. To do this, I would use powders in the range of H4350 and N150.

With 100 fps as the goal, work up your loads in small increasing increments, follow proper reloading practices, and back off the moment you detect any pressure signs. YMMV, but that's the approach I'd take.

Thanks. Some good input. It makes me think I might use a Speer offering that is a 130gr with a nice .411 BC. The 140gr from Sierra is only a .416 so I would give up little in downrange performance (assuming terminal ballistics are good). I would also pick up some velocity. Hogdgon lists no load for H414 (my current powder of choice) and 130gr bullets. SO I will work from their loads for 120gr (48gr-51gr) and 140gr (44gr-47gr).

I think all this through with no more than a 98 action sitting on my bench. Good to plan (dream) ahead. I already have all the parts to go into this project picked. Just a matter of getting back from deployment next year to put it all together.

The 257 is using 90gr seems like it will be a real sleeper. I can't wait to get rid of the 250 100gr loads I have as my wife won't let me get new powder and bullets till the old is gone. By then I will be on deployment. Oh well. Where can I get some +P data for it? I hate guessing. This is the first time I have deviated from a listed load and I worry I might miss a sign. I guess that just makes me more diligent, but....

Oh and I had a chrono. Till it met its end and my check book owning wife says why buy another to shoot it again. I am blessed to have a friend with one he lets me borrow every now and again. Good friend since I killed my own.

 

[Kernel]

With the 130 gr Speer, I still think your powder "sweet spot" is still going to be right around H414 and RL-17. In my view, that bullet is not light enough to justify going to a faster powder. To get a starting load for a 130 gr bullet you can extrapolate from Hodgdon's 120 & 140 grain load data. In this case, the math is really easy, since 130 grains is exactly half way between the two. Based on what you posted, that starting load would be 46 gr of H414 with a 130 gr bullet in the 7x57.

In the same fashion, you can estimate the starting load velocity, max load, and max load velocity. As a target, I would estimate your +P load would be no more than 2 grains over a normal non +P max. Still, work up to your max load, and don't just "go there". Also, if you don't have one, it would be a good idea to invest in a decent micrometer (not just a caliper) and learn how to read case head expansion.

 

[GMFWoodchuck]

Not too sound.........uhh....Obvious I guess. But why try to take a "soft" round and try too pump it up to higher pressures? It sounds like you really looking for a 7mm-08 rifle. Seems to me that you're almost better off taking a modern mauser style action and building it into a 7mm-08.

No matter what you do, be careful.

 

[NCsmitty]

gdcpony, here's a link to a specific load for the 7x57 that's a good full power load. I would back up at least 3 gr and work up to be safe. You might compare loads listed at www.hodgdon.com.

www.reloadersnest.com/detail.asp?CaliberID=45&BulletWeight=140&LoadID=9387

Link to all the 7x57 loads at reloadersnest.

www.reloadersnest.com/frontpage.asp?CaliberID=45

The 7x57 in a good 98 action is capable of good velocity increases over the pre98 actions. I have done the same in my 6.5x55 in a 98 action.



NCsmitty

 

[gdcpony]

With the 130 gr Speer, I still think your powder "sweet spot" is still going to be right around H414 and RL-17. In my view, that bullet is not light enough to justify going to a faster powder. To get a starting load for a 130 gr bullet you can extrapolate from Hodgdon's 120 & 140 grain load data. In this case, the math is really easy, since 130 grains is exactly half way between the two. Based on what you posted, that starting load would be 46 gr of H414 with a 130 gr bullet in the 7x57.

In the same fashion, you can estimate the starting load velocity, max load, and max load velocity. As a target, I would estimate your +P load would be no more than 2 grains over a normal non +P max. Still, work up to your max load, and don't just "go there". Also, if you don't have one, it would be a good idea to invest in a decent micrometer (not just a caliper) and learn how to read case head expansion.

H-414 is my goal powder. Sorry if I mislead you. I am using the last of the Varget in my .257 right now. I have chosen the barrel contour to be an ER Shaw #3 1/2 of 26" length and I will lug it around. I actually figured the max load on a 130gr would be the same as the current 120gr max to achieve a +P load, and you were dead on for a starter load. I also used to rebuild engines so I have good set of mics. Just never thought of it. LOL. I have been using visual inspection.

gdcpony, here's a link to a specific load for the 7x57 that's a good full power load. I would back up at least 3 gr and work up to be safe. You might compare loads listed at www.hodgdon.com.
http://www.reloadersnest.com/detail....40&LoadID=9387
Link to all the 7x57 loads at reloadersnest.
www.reloadersnest.com/frontpage.asp?CaliberID=45
The 7x57 in a good 98 action is capable of good velocity increases over the pre98 actions. I have done the same in my 6.5x55 in a 98 action.
NCsmitty

Thanks. It really helped.

Not too sound.........uhh....Obvious I guess. But why try to take a "soft" round and try too pump it up to higher pressures? It sounds like you really looking for a 7mm-08 rifle. Seems to me that you're almost better off taking a modern mauser style action and building it into a 7mm-08.

No matter what you do, be careful.

There is something to be said for being different. The 7-08 is more efficient, but the first centerfire I ever owned was an old 95 in 7x57 (the .257 I own was the first one I ever fired and I finally got it at auction). I got my first elk with it (well, second- the first was a bow kill). A friend has a 7-08 and loves it, I just want a 7x57 for sentimental reasons and because it is a potent performer. The case strength is not an issue, it is the actions that have been barrelled for this round that keep the factory loads so anemic.

 

[HankB]

With modern cases and a strong modern rifle, I don't see any reason why a 7x57 can't be loaded up to pressures on a par with rounds like the .30/06 and .308 Win . . . just don't try to make a 7mm Mag out of it.

My old Speer #8 manual lists some pretty hot (by today's lawyerly standards) 7x57 loads; Remington case, CCI200 primer, shot from a Winchester M54 with a 24" barrel. Bullet was a 145 gr. spitzer.

54.0 4831 2890 ft/sec
50.0 4350 2823 ft/sec
44.0 4895 2783 ft/sec
43.0 4064 2767 ft/sec
50.0 H414 2801 ft/sec (using CCI250)

Though not specified, I believe the 4831 was the "H" version rather than the "IMR" version, which was introduced later and burns faster.

These loads are hotter than most published data today, so start well below and approach with caution, usual caveats and disclaimers apply.

 

[gdcpony]

With modern cases and a strong modern rifle, I don't see any reason why a 7x57 can't be loaded up to pressures on a par with rounds like the .30/06 and .308 Win . . . just don't try to make a 7mm Mag out of it.

My old Speer #8 manual lists some pretty hot (by today's lawyerly standards) 7x57 loads; Remington case, CCI200 primer, shot from a Winchester M54 with a 24" barrel. Bullet was a 145 gr. spitzer.

54.0 4831 2890 ft/sec
50.0 4350 2823 ft/sec
44.0 4895 2783 ft/sec
43.0 4064 2767 ft/sec
50.0 H414 2801 ft/sec (using CCI250)

Though not specified, I believe the 4831 was the "H" version rather than the "IMR" version, which was introduced later and burns faster.

These loads are hotter than most published data today, so start well below and approach with caution, usual caveats and disclaimers apply.

Did Speer list anything for the 130gr? These loads seem like just what I was looking for. I don't recall seeing a Speer manual locally (everyone stocks the Nosler one though). I will look again.

 

[GMFWoodchuck]

The only reason why I threw the 7mm-08 into the mix is that I'm not sure whether or not 7mm Mauser brass is built as thick, particulary near the base.

 

[HankB]

Did Speer list anything for the 130gr? These loads seem like just what I was looking for. I don't recall seeing a Speer manual locally (everyone stocks the Nosler one though). I will look again.

Yes they did:

55.0 4831 2947
52.0 4350 2960
52.0 H414 2871 (CCI 250 primer)
46.0 4320 2936
46.0 4895 2942
45.0 4064 2924

Again, all are maximum, start well below and work up with caution.

Though I don't load 7x57 myself, I've found some other loads (particularly in handgun) from the #8 manual to be too hot for comfort, but I guess back in 1970 when the #8 manual was published, lawyers weren't quite as pervasive as they are now.

I also believe that Speer worked up the loads in regular firearms rather than SAAMI-spec pressure guns . . . so again, use caution, as YMMV.

Personally, I'd start with today's "mild" data, originally intended for weaker actions, and work up to the "old" loads very carefully in my new "stronger" rifle.