Home Forums Reloading Big Game Rifles 7x57AI MAUSER LOAD

Ok, How do you develop a load for a cartridge that has no data posted any where I have found. I am looking at 120-130 gr. bullets and am open to powder. Thanks

Just guessing here (I load for a standard 7x57)... But i'd Start with max book 7mm-08 loads and work up from there... With 120 to 140 grn bullets i'd give Ramshot Big Game or 6.5 StaBall a try... For old school powder maybe try W760, H414 or Aa2700 (all the same powder) provided you know how and are willing to deal with temperature instability... Again i have no experience with a 7x57 Ackley... Good luck...

Are your cases fireformed? If not, that will be the 1st project. New brass works best. I usually use what ever bullet I have a surplus of & go with a near max load in the parent case of a mid burning powder (3031 thru 4064 or so?) for forming. A warm charge of a fairly quick powder seems to form the shoulder better. A good snap is preferable to a slow push for this & it takes pressure to move the brass around. Hopefully your chamber was cut correctly & the brass is a crush fit on the 1st chambering. Keep the locking lugs greased. With a new to me rifle & brass, I usually start out with 20 cases to be sure there are no hiccups in the process. Better to screw up 20 than 50.

The brass is now usable to begin load development. It may still take 2 or 3 firings to fill out the corners completely. The brass will shorten after fireforming, sometimes as much as .030-.040". It's still not a bad idea after the 2nd firing to trim them to the same length & square case mouths. Use the shortest case length as a guide.

After the cases are formed, you can start load development with a slower powder. An example... With 140s Nosler #9 says that 49gr of IMR4350 is max in the standard 7x57 with Winchester brass & WLRs. If it was me I'd probably start at 47 or 48gr & increase in 1/2 gr increments. Load 2 or 3 at each charge weight & fire looking mostly for velocity & pressure at first. Continue upward until you start to get pressure sign, reach your desired velocity, or you chicken out. You have a bit of feel for this powder now & can start looking for accuracy, just like any other reloading project.

I use case life to be sure of the safety of a load. If you can get 5 or 6 (or more) firings out of most brass & the primers continue to stay in, you're doing OK.

A chronograph is a real good tool to have while doing this, some might say it's essential. Is the rifle a modern strong bolt action? Also be aware of the differences in the various brass maker's differing case capacities. There could be enough between Winchester & Lapua (used as an example only) to get you into trouble. It's best to err on the low side of charge weight/pressure early on when first starting out. Good luck & enjoy the journey.

That's good scoop. Couldn't have typed it any better.

Most of the time you can use published MAX loads for the parent cartridges for the START loads for the formed cartridges.

358WCF, Yes i have about 50 fire formed AI brass. I had planned to load some 130 gr cup and core for starting. I do have some 3031 and I think 4350 not sure which brand, and some RL-17. My end goal is to load some LEHIGH Controlled Chaos 142 to about 2800-2900 fps and I am shooting a Remington 700 action, Proof research Carbon barrel and McMillan stock and have forgotten what trigger. Thanks For the information. Daniel

I don't know about that particular bullet, but generally speaking for that weight bullet using a 4350 class powder your end goal seems reasonable to me.

Daniel,

Please dont be insulted, but I dont know you nor do I know your level of experience so I tried to keep it safe & simple. The 3031 will probably be fine at a near max charge for standard 7x57 for fireforming with the 130s. It takes a fairly good amount of energy to blow out the shoulder to the Ackley chamber. Since I have no idea of your components, I'll leave you to make the charge weight decision if you need to form more brass.

Being 100+ yrs. old the standard 7x57 is underloaded in deference to all the weaker actions that are still floating around. Book loads are mostly on the anemic side too, but most dont say what pressure they stop at.

In formed cases, one of the 4350s would be my 1st choice to try with the 130s, & it may or may not be your huckleberry for the 142s. Using 140 Partitions, 2800-2900fps is no problem in a strong action with the standard 7x57 using IMR4350 in my 22" barrel. It will take a bit more powder to equal that speed in the larger improved case, but I'm sure it can be surpassed quite easily. If'n it was me, I'd go a step slower than 4350 for the 140 class bullets. I'd also get some preliminary data with cheaper 140gr c&c bullets before starting (at the start again) to work with the Lehigh solids. IMR4831 is a tad slower than most 4350s, & H4831 a tad slower than the IMR. H4831SC will get a bit more powder than regular H4831 into the same space. With slow pour & tapping the case, you might be surprised how much more powder fits. Start near book max for the standard case & work upward. You may run out of case space before you hit pressure. That's good information to have in your notes. In that situation if more speed is desired drop back to H or IMR 4350 & start again. Let us know how it all works for you.

Some notes on powders you may find useful. The one new-ish lot of Accurate 4350 I've tried was very close to IMR4831 grain for grain all else the same. Same with Shooters World 4350. Lot to lot variation can also be irritating at times. RL17 to 23 or maybe even 26, may be great choices for you. Speer #15 has new data for the RL powders if you choose to try them. A word of caution... I've tried some of the newer hotrod ball powders (PP2000, Staball 6.5, & especially Superformance) in a few different Ackleys & have noticed that they seem to spike very quickly when approaching max. Both Ramshot Hunter & Big Game seemed to behave normally so far.

358WCF, I will try to remember to keep you informed with the AI but at the present time, the wife and I are still deer hunting 3-5 days a week. BTW I don't get offended very easily especially when asking questions. Thanks Daniel

Man, I’d love to see a picture or two of your rifle Daniel! Sounds like a peach.

beretzs, I don't have any pics at the present but send me an email address or a cell number and I will take some and send to you. Nothing outstanding in the looks Department but should shoot good. I got it for the wife with plans for her to use it on out elk hunt but the rifle turned out to be too phyiscally large for her to handle. I should have sold it long time ago, just haven't. Daniel

Just seen this. PM inbound.