Home Forums Reloading Big Game Rifles Imr4350

I am trying out a "new" Mauser. 7x57 is new to me, so I am playing around with some loads.

I wanted to start low. The Hornady manual goes way down to 40 grains of imr 4350, but two other manuals state 45 as the minimum.

I know it's bad to reduce slow powders in general...

What do you guys think?

I loaded 43 grains to start. Won't shoot them til I hear from some of you guys

Bullet weight?

139 hornady

My Lyman book sets minimum at 43...I am going to let that be the tie breaker.

Nosler says 45 gr. is 91% case fill. 40 gr. works out to 80% fill. I would shoot 40 with no issues.

Ok so a ten percent reduction is not a big deal. The explosions are from big reductions I guess?

Take a look at Hodgdon's data for IMR4350 with that bullet in the 7mm-08. The start load is 45.5 grains. The top load is 48 grains and that's at only 45,200 CUP. The 7x57 is of greater capacity and will produce lower pressures for a given charge.

Ok...and I extrapolate that to mean, what, exactly? Are you saying pressures are low so it's ok, or that pressures are low, so don't do it?

Unless you're working with a weak old rifle it's a waste of time and components to start with the listed low start charges for the 7x57.

Ok. Thanks.

My M98 Mauser 7x57 shot great with 46.0 grains of I4350 under a 160 grain Speer. I'd say you could easily start at 45grs. under a 139 grain bullet. I'd be very careful with a M93 or M95 Mauser.

I would be very conservative and probably start at the hornsdy recommended start loads. If those are OK pressure wise you can move up quickly to where you think you want to be. It will only cost $5 to$7 extra to do this. I say this for two teasons:
Mule deer has stated that chamber and throat dimensions are all over the map with the 7x57.

Also your lot of powder may vary from the book lot. I have 7 lbs of IMR 4350 that is 2 to 3 grains faster than book loads in my 270 and 3006. Have fun with your net toy.

My reference to 7mm08 loads takes these things into account. They have much more uniform shorter throats than the 7x57, and the case has less capacity. It follows that for a rifle suitable for modern pressures that working up from 7mm08 data will take care of the 7x57.

IMR 4350 is my favorite powder, has to be now since I have a bunch of it.

Agreed.

When I started loading for my Ruger M77 7x57 in the early eighties, the Hornady reloading guide listed a max load of 53.0 gr IMR4350 with 139 gr bullets. Worked fine in that gun for many years and over 1500 rounds of that load have been through the barrel.

I'm in this same camp - when working with a former Ruger #1 in 7x57 and your IMR4350/139gr Hornady combo, I started with 47.0gr and worked up to 49.0gr with no issues.

The world is full of loads for the 7x57, I wouldn't mess around with 7mm08 data.

The existence of 7x57 loads was not the point of the post. It was about a reasonable and safe way to cut to the chase if you're loading a modern 7x57 rifle. It's also useful if you're interested in trying a newer propellant for which 7x57 data isn't yet available, but 7mm08 data is.

This is spot on. When I began loading the 139 gr Hornady in a Ruger M77, I had three sources all in the M77 with 22" barrel. Hornaday manual fourth edition, Hodgdon manual sixth edition and Bob Hagel's GAME LOADS AND PRACTICAL BALLISTICS FOR THE AMERICAN, HUNTER, and all three had a maximum load of 53 grains.