Why? different load pressures.. same load...

[atvalaska]

Hodgdon gives imr 4198 a low of 47grs a high of 50grs same 400 gr speer bullet...an the SPEER book sayz 42 grs on the low side and 46 on the high side .. (45-70 with both books saying there in the single shot modern rifle/49000cup range) HOW can there be that much range in the results ? near as i can tell its a 24" barrel ... i know start 10% down and work "up" your load...

 

[Dean Williams]

The pressure range they give is going to be for the loads at the upper end of the charge weight. Hodgden and Speer recorded data that showed safe in the their individual equipment. Every barrel/chamber is different. Different chamber, different rifling, etc, just from variables introduced during the manufacture of the barrel.
These things affect pressure. So do things like seating depth, primer, case brand, and even what dies they used to size the brass.

It's pretty common to have different powder charge maximums from a number of reloading sources.

 

[rcmodel]

Hodgdon uses a SAAMI spec 24" pressure test barrel in a Modern Bond cannon-breach receiver.

Speer used a Ruger #1 with a 22" barrel.

Both used different lot #'s of IMR-4198, at different atmospheric test conditions, several months, or years apart.

rc

 

[buck460XVR]

My feeling is your best results will come somewhere in the middle. One reason I tend to try and verify a new load with at least three different references. To figure out where the middle ground is and to establish a starting load that will require the fewest adjustments to make it a shooter. There are many starting loads listed on the Hodgdon site that are above and beyond the Max loads listed in some of my other manuals......and vice versa. Many times I have gotten to the limit of where I feel safe with a load before it even gets to the starting load listed in some books and websites....again, why I reference more than one source. From my experience, those that hafta have the biggest and the baddest will usually start with the hottest recipes and those that are recoil sensitive will generally start with the softest...me, I tend to stay in the middle of the road and find a nice accurate load that don't beat me up too bad.

RC gives some reasons info may vary....I believe how much influence their corporate lawyer has may make a difference also.

 

[dagger dog]

atvalaska,

For insight on the subject read: "WHY BALLISTICIANS GET GREY" by Dave Andrews pg.# 443 in SPEER RELOADING MANUAL RIFLE AND PISTOL #13