"if shooting competitions check the rules. No metal of any kind allowed sand or Zircon sand only."
What discipline would that be?
I would be willing to bet that if you checked the bags at sanctioned matches most that contain heavy sand would not be zircon. Sinclair has been selling non complaint heavy sand for years, that I am sure is in wide use in the benchrest game. Actually, sand is not a specific mineral but rather a particle size range. IMO the IBS rule suffers from inappropriate over specificity that serves absolutely no functional purpose, since there is no functional advantage that I know of derived from using any mineral sand. In fact, am not sure that there would be any advantage from using steel or lead as long as the particle size fell within the size range of sand.
Added a few minutes later: I think that is is worth noting that there are significant differences between the short and long range bag fill rules in the NBRSA.
This is the long range rule.
"
A sandbag is defined as a bag with or without a pedestal, with a leather or cloth cover, that is
capable of being easily flexed by the fingers, and contains a dry finely divided nonmetallic
substance such as, but not limited to, sand, gravel, or grain, without additive and packed
loosely enough that the bag can be easily deformed by pressure of the fingers. The cover of
the sandbag must not be bound in such a manner to prohibit free movement of the contents.
Velcro cloth may be used on sandbags ONLY in Long- Range BR Shooting Competitions.
Lubricants such as talcum powder, Vaseline, mica or friction reducing tape of no more than .
011" total thickness may be used on the bag for lubrication."
Within the rules for front and rear bags, the only fill requirement is, "... containing sand only..."
Personally I like the long range rule better. But the short range rules allow the garnet sand that I use in the base chambers of my rear bags.
The IBS long range rule is as follows:
"
Sandbag. A sand bag is defined as a bag with or without a pedestal, with a leather, cloth or
290 synthetic cover that is capable of being easily flexed by the fingers. They may contain a dry
291 finely divided nonmetallic substance such as, but not limited to, “Heavy Sand”, sand, gravel or
292 grain, without additive and packed loosely enough that bag can be easily deformed by pressure
293 of the fingers. The cover of the sand bags must not be bound in such a manner to prohibit free
movement of the contents. Lubricants on the sand bag may be used. Front and rear rest sandbags"