Thread: 7x57mm 1st effort - comments?

Hi people. per some other posts I picked up an Interarms Mark X in 7x57mm early Dec, a new calibre for me. Rifle is in what seems to me to be a fairly basic plastic stock at the mo. I had 2" chopped to remove a barrel bulge at the front and have it threaded (14x1). Gunsmith liked the rest of it well enough to give a thumbs up. So into some reloads with used brass kindly supplied by a Forum member and a part pkt of 130gn Speer Spitzer SP with flat bases I bought from a mate to try. There only being a few of them explains the first three loads being only 3 rounds. I took it to our club pistol shoot on Sunday to chrono the loads after the range cleared off, being excited to have a go and all that. Wasn't a flash effort, just using a front rest on a table, target at 58m on range finder. So hardly Bench Rest standards. Scope is a Vortex Crossfire II that I bought from a Forum member and mounted on new Burris steel rings. I intend the rifle as a general purpose hunting carry and will go to 139gn FB SP projectiles in all likelihood.

Anyway, as you will see from the data sheet below, the test rifle was a 24" barrel with 1:8.75 twist. Mine is now exactly 22" and a measured (by me) 1:8.5" twist. Mine is a large ring 98 pattern Mauser action.

The first load was also my sighting in shots, the scope being only bore sighted. I had a standard IPSC paper target up with black squares, one in the center, and in each corner. This first load was aimed at the center and hit up at the left corner lol. Used a sighting vise to make the adjustment, all remaining loads were aimed at the black square in the frame.

I would put a fair amount of the variation down to the shooter - I'm no gun at this (pun intended). Intention is to repeat with proper sandbags front and back. In the meantime I would be interested in comments on the following:

- The increase in velocity from load to load seems a bit out of wack to me. You would be forgiven for thinking I had mixed #1 and #2 up. However I assure you my prep is meticulous with each group separately bagged and labeled and each round with the charge written on it in marker pen. Clearly a repeat is in order. I would be interested if others find the same sort of pattern or if this just convinces you of user error?

- At the max load I had two rounds chrono slightly above the ADI sourced datum - though my barrel is 2" shorter. All loads are trickled using a Dillon Beam Balance scale to weigh. All the brass was Winchester multi-fired, tumbler cleaned, full length sized and length gauged with lightly chamfered mouth. Dies are older Lyman ones and no crimp was used. neck tension seemed fairly strong to me. There were no discernable pressure signs on any of the loads. Extraction was consistent and real easy. Question is, would you risk going another two 1/2 grain steps?

Anyway, hope you find this interesting. I have a bunch of different projectiles in small numbers to try out plus some full boxes of 139, 140, and 150gn. I have other powders I can use also including Benchmark 2 and RL19.

Looking forward to your (constructive) comments.

Only comment I can add, I always used W760 powder & a magnum primer for the 7x57 with excellent results. 760 is a very dense ball powder, so the mag primer was a good option for ignition. From memory the 130gr was spinning along at around 2900fps. Medium to slow burning powder is the key for the 7x57.

Don't have 760 but the RL 19 is a slower powder so might head to that. Cheers

I would consider seating depth at 40gn and also creeping aup from yr test max.

Originally Posted by Woody

I would consider seating depth at 40gn and also creeping aup from yr test max.

Ok so not clear what you are suggesting re seating depth..seatess for longer COL? Or seat deeper?

Jhon,

Some general comments on loading for the 7mm Mauser from my experience with ex mil 98 spotters and a rimmed single shot. I support Mathais’ comments on WW760, it seems to be excellent in this case for both the accuracy and velocity relative to other similar burn rate powders like 2209.

A lot of rifles will have a very long throat set up for 160-175 wt projectiles . So seating lighter pills close to the lands is not possible. With the 1:8.6 Mauser twist light projectiles will often not group tightly.

In my ex mill Mauser it was a 154 gn hornady sp that grouped tightly. 139/140s did not group well. In my single shot, 140s are fine.

The last point I’ll make is regards to velocity, a 154 at 2650 fps was about max as is 2800 with a 140. I always struggled to get top 7mm-08 performance, but both loads work very well on game.

Cool caliber its in my to get list

Originally Posted by Jhon

Ok so not clear what you are suggesting re seating depth..seatess for longer COL? Or seat deeper?

Consider both and keep an eye on pressure. Same goes if you try upping the charge. If you have not seen any pressure signs yet then I would be a little curious as to why you have not found a second node yet.

Have a BSA Viscount in 7x57. With 140 Sierra pills it grouped best at 44.5 and then at 47.0 of H414 (which is W760 with the Hodgon label)). Seated 30 thou off the lands. Sub moa consistently with those loads. ADI 2209 is also a good powder for this cartridge, have seen some stunning groups out of a BRNO with it.

Originally Posted by Mathias

Only comment I can add, I always used W760 powder & a magnum primer for the 7x57 with excellent results. 760 is a very dense ball powder, so the mag primer was a good option for ignition. From memory the 130gr was spinning along at around 2900fps. Medium to slow burning powder is the key for the 7x57.

I've got some H414 ball powder, about same as W760 I understand. What's the deal with the magnum primer? Is it really that hard to ignite? And does it matter if you use a regular primer if the case is near full?

I acted on info from another user of W760, who's advice was to go magnum. I guess if you have the time, try either and check ES etc on a crony.

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If you have no pressure signs I'd go another half gn and then see
I'd muck with seating depth from 40gn

Originally Posted by Cordite

I've got some H414 ball powder, about same as W760 I understand. What's the deal with the magnum primer? Is it really that hard to ignite? And does it matter if you use a regular primer if the case is near full?

Recent brews of H414 and W760 are the same. That wasn't always the case.

YOU MUST ALWAYS USE A MAGNUM PRIMER WITH W760 except in my 6.5 Ackley I don't. In 800 shots I had 1 misfire and that was a plain and simple dud primer.
Told I must use magnum primers so gave them a go. Got slightly higher velocity and twice the ES. Back to CCI BR2's.

You would need to try magnum and standard though in your combination as your results may differ.

From Hodgon site H414 & W760. First I've heard of having to use Magnum Primers. I use Federal 210 Std Rifle Primers no issues. But in saying that go with whatever works for you. That's the fun of reloading.

Manufacturer Powder Bullet Diam.
C.O.L. Grs.
Vel. (ft/s)
Pressure
Grs.
Vel. (ft/s)
Pressure
Hodgdon H414 0.284" 3.000" 44.0 2,548 40,400 CUP 47.0 2,715 46,000 CUP

Wincheste 760 0.284" 3.000" 44.0 2,548 40,400 CUP 47.0 2,715 46,000 CUP

Yeah W760 morphed into H414, or maybe the other way around, around the time Hodgdon took over the marketing of Winchester powders. Old old reloading data should show a difference between the 2 though.
And according to oil you should use magnum primers with ball powder.
No sure how my little Hornet using W296 would go with magnum primers. Maybe I could leave the powder out and just use the magnum primer?