Standard Block Dimensions   1.5"W x 1.5"H x 1.75"L.   These blocks are optimal for bullets in the 180 - 300 grain range, depending on alloy.   300 to 425 grain bullets are sometimes made in these blocks but heat-related fill problems may occur, depending on alloy, mold material, and casting technique.   As a single cavity, the standard block cast well with 400 - 1000 grain bullets.
XL Block Dimensions  1.5"W x 1.5"H x 2.25"L. The 2-cavity XL blocks are used for bullets 325 - 1000 grains, though anything below 400 grains may be cold natured.
Handles  are not included. RCBS handles will fit, Lee 6-cavity handles will fit, and current production Saeco/Lyman handles can be modified to fit.
Aluminum  blocks are made from either 2024 or 7075 aircraft alloy.   Aluminum seems to be better than other materials at avoiding overheating problems when casting very large bullets.   On the down side, all aluminum alloys loose much of their strength at bullet-casting temperatures, and care is required to avoid galling where the sprue pivots.
Brass   Brass resists corrosion and machines beautifully.   On the downside, brass is heavy.   Being cold rolled, it does have residual stresses and it can warp a tiny bit after machining, though rarely does it warp enough to create a noticeable problem with standard size blocks.   Because of the weight, we currently do not use brass for XL blocks.
Sprue Plates  are made from 1/4" steel that has been heat treated to reduce warping.
Alignment   Stainless steel male/female bushings.
Ventilation   Vent lines are cut on both halves of the block.