load development - 7x57 mauser

gentlemen -

it's my intention to make this a running thread so that it might be useful to anyone who is looking to develop a load for this cartridge. if anyone else is beginning development on a cartridge for target shooting, varminting or big game hunting, perhaps they could start a similar thread as well.

cartridge - 7x57 mauser, also known as 7mm mauser and .275 rigby

rifle - cz m550 american

application: deer and antelope hunting on the open prairies of north-central montana

for the moment, i'm using a lee loader. with luck, this should change soon, but in the meantime, i've had good luck using this tool with my .308. the lee loader, as you all know, neck-sizes only. with a bolt action rifle and trimmed cases, i don't see this to be a problem.

starting completely from scratch, i've got around 100 pieces of once-fired (in my rifle) winchester brass.

i'm looking for suggestions on:

bullet brand, type and weight. my first choice is the sierra gameking. because i hunt in open country, fairly long shots are a definite possibility. SGKs have a good reputation for accuracy. i figure that of these three choices, 140-, 150- or 160-grain, 150 would probably provide the best balance in terms of versatility (long or short range) and terminal durability. this is the bullet i intend to use, but i'm open to suggestions.

powder - i've heard great things about varget, so this is a good potential choice. i'd like to hear more about it if anyone has any experience (TimberGhozt!). lyman's 47th ed. mentions that IMR 4350 best combines accuracy and uniform ballistics. lee's 2nd ed. seems to favor something called a-xmr-4350, which i have never heard of. once again, i am open to suggestions.

primers - i intend to use winchester large rifle primers, although i might load some identical loads with CCI for the sake of comparison.

COAL - Lyman recommends a minimum overall length of .3025 inches. lee recommends 3.060. not sure why the difference, but unless i hear otherwise, i intend to go as far out as the magazine allows, assuming that i seat the bullets at least as deep as a caliber width (.284). suggestions would be appreciated. i do not intend to crimp.

that's what i've got for starters. let's get some ideas going!

Taz;

Speer #13 used the Ruger M77 with a 22" barrel to develop the test loads.  They used Remington brass & CCI primers with a COL of 3.065".

The three Speer bullets I'd consider are the 130, 145, and 160 grains.  All weights are available as either boat-tail, or flat-base spitzers.

With the 130 grain bullets, the three powders producing the best velocities are:  H414, magnum primers, start 46 gr - 2649 fps, max 50.0C - 2960 fps.  Win 760, magnum primers, start 46.0 gr - 2627 fps, max 50.0C - 2952 fps.  And RL15, start 41.0 - 2624 fps, max 45.0 - 2915 fps.

When we go to the 145 bullets it's:  RL19, start 48.0 gr - 2543 fps, max 52.0C - 2795 fps.  H4350, start 46.0 gr - 2520 fps, max 50.0C - 2784 fps.  And AA4350 47.0 gr start - 2481 fps, max 51.0C - 2757 fps.

At 160 grains, velocity is fallin' off pretty steeply.  Win 760, magnum primer, start 42.0 gr - 2371 fps, max 46.0 gr - 2605 fps.  H414, magnum primer, start 42.0 gr - 2363 fps, max 46.0 - 2582 fps.  And IMR 4064, start 38.0 gr - 2263 fps, max 42.0 gr - 2573 fps.

I would certainly try some testing with the 130 grain bullets & see if they're tough enough for antelope & deer.  I suspect that they are, as Speer specifically states so.

Edit:  Speer #13 notes that the above loads were developed to the +P standard of 50,000 CUP, and specifically warns against max loads in pre 98 Mausers, Remington Rolling blocks and other older or suspect guns.

900F

comments from www.accuratereloading.com:

http://forums.accuratereloading.com/eve/forums?a=tpc&s=5 18103&f=2511043&m=855106616&r=951102716#95110271 6

   If you look through the arkives you will find some pictures of groups I fired with my 550 full stock. (I sold it recently). I got great results with RL-19 shooting bullets of 160 grains, and H-414 was the best powder for 150s on down..

     I have done up 3 loads for my new Rifle,See pic on the rifle page.

  I don't expect the #1 to shoot as well as MY CZ but I bet it gets more use. I,ll hopfully get to try it out saturday or sunday, Ill let you know how she works out.

   My #1 is just like bears except the XXX walnut, but I put a 2X7 on mine too...tj3006

Hey 7X57,

   I use lots of H-414 in any of the 4 rifles I own that shoot rounds based on the mauser case.

   But I thought you might find some value in somthing I learned with a CZ 550 full stock i used to shoot.

   While I used the 414 with 140 and 150 grain bullets , but with 160 and up I switched to RL-19.

    I got many 1 hole groups with this combination., and better velocity too.

   I sold my CZ and bought a lite weight #1 ruger. It has a similar throat but I can get better performance with the 140 grain bullets. And even though I have 1.5 inches more barrel, the overall rifle is much lighter and handier in the woods.

   Of corse the trade off is that while the ruger is plenty acurate with loads it likes, The CZ was acurate with most anything.

   Have you tried a lighter bullet in your CZ ?

   While we have all been told loading close to the lands helps accuracy, I have shot lots of rifles that have short boxes and long throats but shoot great !.

    ...tj3006

Does that have a1:10 twist or the Euro 1:9 twitst. I spent about a year working up loads for a Interarms  7x57 with the 1:9 twist and found that  it just wouldn't shoot the  140 gr clas sbullets , but loved the 160 grainers. I tried Varget, 4064, 4895 , 4831 and 4350. 4350 worked the best. In the 140 gr bullets, I tried every long bullet I could find, but just couldn't get there.

This rifle had a very long throat also, and I found no difference in seating depth. Some of my loads wre 1/4" from the lands 

Take a tight fitting patch on a cleaning rod. Insert in barrel. Place a mark on the rod and start running it down the barrel. When the rod makes one revoulution. Place another mark onthe rod. Remove rod and measure the distance between the marks you made.

This wil give you the twist rate. One revolutionin XXX inches

   Thought I would post the results of some Chronying I did with my 7X57. With 50 grains of H-414 over a 140 grain nosler Balistic tip, I got 2833. That load is real acurate. I also shot the same bullet over 51 grains of H-414.

     It only boosted velocity by about 30 FPS so I will stick with the 50 grain load...tj3006