Regulation loads

[rigbymauser]

Many things, many books and many forumthreads is written about the experience of doublerifle regulation and how to.

What I want to ask the good folks here if one have experienced regulation diffence when changing bulletstyles?.

I have a nice Cogswell & Harrison in .500ex 3" from mid 1880s. Normally when seing charts from the past the 360grain solid roundnosed bullet regulate at 1800 ft/sec. However I have used Keith style bullets weighing 355grain, but these regulate very well at 1620 ft/sec at 100 meters. I know the flightcharateristics of the SWC is different than from a roundnosed. Has anyone observed this?. I know the ballistic charts from the 1880s can vary and the methods of measure velocity wasn`t as precise as with todays gear.

Generel comment is the 355grain is sweet to shoot. 6 shots within a fist at 100meters. I will try my roundnosed 340grain hollowpoints here in the spring.

 

[Red Leg]

Anything - any change from the original regulation load - powder, bullet, even the man holding the rifle - can affect regulation.

 

[Aussie_Hunter]

Anything - any change from the original regulation load - powder, bullet, even the man holding the rifle - can affect regulation.

Agree with this 100%. When I was working on load development for my 470 double I couldn't believe the difference in accuracy just from using different powders. I have seen very slight differences through bolt guns before with different powders but the difference through my double was significant. Definitely worth spending plenty of time on load development especially if the original load data used for regulation is not available.

 

[rigbymauser]

I was surprised to see how 3 grains of powder changed everything. I used 54grain Norma 200 to a 355grain SWC as starter. They spreaded all over. 51grain and it regulated flush with the 100yard sight. Tried different types of 440-460grain bullets with different charges. That gun isn`t made for this weight. Some shots were of the chart. Couldn`t even see a impact on the big dirtbank. However Its gonna be interesting to shoot a traditional roundnosed bullet. Maybe they can be generated to more speed and still regulate. Its so sweet to shoot these 355grain at 1620 ft/sec. Recoil is a like a .308win. I am also gonna try some FFG with the 340grain roundnosed. These guns were afterall regulated with blackpowder which recoils diffently than smokeless. My Manton 10bore shoot cluster groups with Swiss 1,5 at 40yards were the smokeless loads spread more. The absortion of recoil also matters in regulation.