7x66 or 7mm improved any load data?

stugatz

stugatz

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A friend of mine aquired a custom bored shultz & larsen rifle re-chambered from a 7x61 s&h to a 7x66 or 7mm improved complete with rcbs dies. My question is does anyone out there know of any loading data for this caliber,I am having a hell of atime finding anything on the internet......stu
 
Try reloadersnest.com for free data............It would have been easier to keep it as it was............at least Norma makes brass..........Harold
 
If my memory is correct, cases are formed by either passing a .300 H&H (or any of the mid-size Weatherbys) through the size die.
For data I'd use 7mm Weatherby.
 
Splatter said:
If my memory is correct, cases are formed by either passing a .300 H&H (or any of the mid-size Weatherbys) through the size die.
For data I'd use 7mm Weatherby.
Click to expand...

X2.

You need to know its case capacity. Then you find another 7mm cartridge with the same or slightly more capacity and use loads for it.

The 7x66 has about 4% more capacity than the 7mm Weatherby (~90 grs of H20), so those loads should be fine in the 7X66. Weatherby loads hot and employs lots of freebore to compensate, but the higher capacity lowers the pressure a bit to compensate.

The "7mm Improved" - I dunno. It could be anything - you need to know its case capacity before you can do anything.
 
To clarify... If I'm remembering the right cartridge, after you run the H&H or Weatherby case into the die, you've got to fireform it to the chamber before you can start to put the big loads in it.
The nice thing about belted (or rimmed) cases, is that you don't have to worry about headspace for that initial firing.
 
I thought the 7x66 was based on a 300 Win Mag necked down to 7mm, the 7x66 Randle (also called a 7mm Yukon). In any case, yes, you could start with 7mm Wby data and work your way up. Your load range will be in between the Wby round and the 7mm STW. I have load data at home, but I'm traveling again, so don't have access, sorry. - dan
 
Dan i do belive you are correct, he has some already loaded rounds that he got from the estate of the previous owner that are headstamped 300win mag. He unfortunately does:evil::evil: not know what type of powder is in those shells. At any rate thanx to all your responses but if anyone has some proven loads it would be appreciated thanx......stu
 
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