Mold designation please!

[srk]

HI Everybody
Can someone please help me with a mold designation.
I am in the process of buying an "Ideal Middlefield" rifle mold for my .25-20.
The numbers stamped on it are as follows. "257-388-137"
Now I assume the "257" is the dia.
Not sure what the "388" is.
Would the "137" be the cast weight of the bullet?
Any help would be greatly appreciated.
Thanks
Srk

 

[Arctic]

If it's a Lyman, that's an 80 grain gas check bullet.

 

[ben hunchak]

Yes it is a long discontinued, Spitzer gas check design of 80 grs. by Lyman, any "Ideal" marked mold will be older and this mold may have only been made when the Co. was called "Ideal". If you get a look at the design, see if it has a good parallel length of groove depth sides or bore riding sides, as cast bullets that have the shape(taper) of jacketed bullets don't usually work well, Lyman explains it well in their Cast Bullet Handbooks( It's harder to explain without pics.)...Ben

 

[Silverback]

Here is a good link for pictures and weights of all the Lyman/Ideal moulds: http://www.three-peaks.net/bullet_molds.htm