Greetings all,new here so thought to introduce self and mention what Im shooting to save confusion.
I had an old single barrel astra cyclope shotgun,been in family for 45ish years...bought a home spun .45cal barrel blank,clever fella drilled and rifled it in back yard...got a friend to spin it down on a lathe untill it slips snuggly INSIDE the .12ga barrel,chambering to .45/70 was done wit ha boring bar set at ever so slight angle and we were away.... I load it up to top of trapdoor levels/bottom of next lot.... around 45 grns of AR2208 with a 400grn cast works well.
THEN the BP bug bit so rolled my own using bristler sits recipe,except the seive through mesh bit was just too hard so chopped it up with old ruler as it dried and just kept doing so untill it was a good consistantcy....still the odd wee lump of sulphur but generally not bad.
this same buddy also turned me up a 12" insert for same gun that fires a .410 shell or .45 long colt...now that my friend is one heck of a lot of fun.
there is no smaller diameter barrel it is same from rim to muzzle but it generates enough pressure due to having 9" of barrel to burn in.the shot will be starting to spread then hits the choke of .12ga barrel and sort of sneaks back in a bit...its good enough for rabbits at 20 yards,and my good Wife took two mallard drakes with a single round!!!!! I wasnt sure if should be proud or jealous.....wisdom said be proud....
possums up trees are just too easy with this adaption.
crude open sights on the old shotgun barrel have been ok but after missing a couple of easy deer...close to hundred yards isnt ideal with crude sights,so Ive fitted scope and in process of sorting zero and then loads...... pretty sure the straight BP loads and straight smokeless loads are fine...Im hoping its either the duplex loading or the cast projectiles I got given are why Im having issues getting zero sorted.