Point of Impact Question

[oldracer]

Well today I went out and did some test fires of the 300gr and 500gr boolits I had cast. These are fire from the 45-70 rolling block I have mentioned in several earlier posts which has a 34 inch Badger barrel and 2.5 # trigger. The loads are as follows: 300gr from a Lee two cavity mold with approximately 65gr of ff black powder. 500gr from a Lee two cavity mold with about the same powder load. I compressed the powder, used a wax milk carton and then a newspaper wad on top of the powder and neither boolit was crimped. I also loaded some 300gr (same as above) with 40gr of IMR3031 with a foam wad made from artificial flower foam. The smokeless was not compressed to any great degree but about filled the case. I used Winchester Large Rifle primers in all loads.

At 100 yards I tried several different front sight inserts and finally settled on a central circle that fit the stick on targets with a slight amount or white showing around the center.

The 300gr and 500gr had almost exactly the same point of impact with the 500gr grouping about 1/2 of the size of the 500gr. That I can relate to the lighter boolit not getting stabilized possibly but when I shot the 300gr smokeless loads they shot nearly 6 inches higher? The 4 shots were nearly touching which made me feel really happy since I can barely see that far!
My question is why did the smokeless have that much higher impact? Were the black powder loads already falling possibly but I think that were not climbing as fast possibly? Any thoughts will help me in my new endevor.

[NickSS]

Your black powder loads were going slower than the smokeless load hence they hit higher on the target. As far as your 300 gr black powder load it is possible that the twist rate of your badger barrel is like mine at 1 in 18. This rate is ment for stabilizing big long bullets going slow, it may be too fast a twist for short bullets or your rifle did not like the load. only trying other combos will tell. It sounds like the light bullet does work with smokeless though.

[bigted]

nickss...isnt velocity just velocity?? black or white powder shouldnt make a diff if the speed is the same correct?

i understand the 18 twist should level out with the longer boolits better however...why does the smokless loads group better then the blackpowder almost every time? [ with the shorter 300's that is] it seems to me that if an 18 twist barrel will stabilize a 300 with smokless then it should do the same with black...rite???

just ramblings that twisted thru my meddeling mind

[oldracer]

Thanks for the thoughts. Besides the tighter grouping, I am really wondering why the smokeless loads shoot 6 inches or so higher? I guess I should have taken my chronograph with me but my thoughts at the time had me thinking that the 300gr loads (both) would shoot higher than the 500gr loads so this weekend or next I'll be sure to take it. I need to go when it is really foggy so I can try to catch the flight paths also with a spotting scope.

[NickSS]

The difference can be that the speed of the bullet is different between the two loads and that could make all the difference or it could be that the load with black was not compressed as much as with the heavier bullet. There are so many variables that it is hard to say. I have gotten 300 gr bullets to shoot really well with both types of powder but they never shot to the same point of aim.