A whole series of large diameter, swivel type, double tube core barrels have been developed and accepted as standards by the Diamond Core Drill Manufacturers Association. This series includes those sizes that are larger than "HWG" design.

Construction features are much the same as for "M" design barrels, but because of the larger sizes involved, these tools are more sturdy.

A good axiom to remember is, "The Larger the hole, the better the chance of a good core". Large design barrels are in use wherever extremely difficult coring materials are encountered or where actual large, physical volume of core is required for tests and analysis.

Sizes of these barrels are shown below. First, numeral indicates core size, the second, the size of the hole. Note that the two larger sizes are equipped with sludge barrels to help keep a clean hole.