Acceptable rifles must be of BPCR Silhouette configuration, (exposed hammer, no hooked butt-plates or palm rests). They may be originally chambered for .22 rimfire, converted/re-lined, or BPCR Silhouette rifles with removable liners/insert chambered for .22 rimfire. Sights will be open globe front sights and tang/peep rear sights permitted. Scopes or sights with iris-type adjustmants are not permitted.
In the same manner that BPCR Silhouette rules prevent a technology race, these same rules are encouraged for .22 LR Silhouette for the same purpose. As stated earlier, this game was originally intended to mirror BPCR Silhouette in all respects.
Above is quoted from the 22 BPCR website.
Here is the link to the NRA silhouette rules book. Section 3 has the info on BPCR rifle specs.
http://compete.nra.org/documents/pdf/com...r-book.pdf
Hope this helps, Cody