Again this is just my take on it and other results may very . I shoot in about 25-30 lbs of powder a year and this is what I have found . But again others results my very .
When working up a load for a rifle we know that changing small things like Lube , patch thickness , ball size and amount of powder have a great effect on the end result .
If you used AP to get the first group and have not changed the make up of you load and only changed the sights . Well then its probably the sights that’s giving you the issue . Which would mean you actually had the other sights performing better then these new ones
If however you went from BP to using AP , my bet is that it’s a combination of the powder and the new sights .. If the sights are solid and of a design that will prove consistent, then the problem is with the powder .
Did by chance you change to a peep sight ? If so it may take you alittle time to naturally stop fighting the alignment of the sight . Some folks have a problem with that and until they get used to the sight picture , they are all over the paper
With powder 5 grains can change things , sometimes dramatically and make the difference from shooting a 6 to 8 inch group and shooting a 2 to 4 inch group . Depending on the barrel and rifling , it can make the difference in shooting a 1 to 2 inch group .
This isn’t just with synthetic powder . Differences in BP manufactures also have this problem .
Swiss is hotter the Goex . Goex is hotter then the old DuPont, all of which are hotter then Elephant
The same order I find to hold true in how clean they shoot as well .
See different Charcoals make for different burn rates and hotter charges , thus higher barrel pressures
But this gets compounded when you compare synthetics to BP .
While they are listed as an equivalent, that equivalent is based on a few things but te biggest is
the way its measured . But the other numbers are sometimes greatly different .
Take the pressures for instance . While velocity increases are sometimes marginal , the pressures for like loads are not .
But remember how they achieve that pressure is different . This is why synthetics are considered propellants where BP is considered an explosive. They are different in their burn
If we take the numbers NW hunter posted and forget about the flbs and just look at velocities . We see we have a 140fps increases between 40 and 50 grains . 256 between 40 and 60 grains
If we look at the compression that Lyman gives fro the 36 cal with a RB twist of 1-66 and a 26 inch barrel
We can see that there really isn’t much difference.
40 grains of 2f goex is giving FPS at 1878 . Pyro RS - 1954
Goex 3F , 40 grains , fps = 2070 . Pyro , select =1982
But if we through caution to the wind and were using say goex 2F and then someone said to try pyro P you just change your velocity by 225 fps . That computes to a change in trajectory
BUT here is the big change Pressure
Lets say you were using 40 grains of 3F Goex in your 36 .
. That 40 grains will produce approximately 9,900 PSI . but that same charge of Pyro RS = 11,800. Pyro select 16,400 . Pyro P 16,100.
So lets say you went to that 40 grain charge because while working up a load , you found that 40 grains gave a better group then 50 grains .
Why ? Well that’s from many things but the tell tail compression is pressure not velocities ..
That 50 grain charge of Goex produces roughly 10,400 PSI .
So if 50 grains of 3f Goex gave a worse group then 40 grains of goex which only produced 9900. we have to assume that any pressure higher then that will effect your group . So the Pyro charges would be even worse as even Pyro RS is achieving 1400 PSI more at 40 grains then a charge of 50 grains of goex .
If we look at the PSI numbers for both Pyro select and Pyro P and compare it to that same 50 grains of Goex , we are looking at 9200 PSI difference within the bore , for the same volume of powder .
So see its important to know what your shooting in powder and what that powder is doing . don’t just look at velocities and say ahhh its close because the case very well maybe that its truly not .
What AP numbers are , I don’t know . I know I have tried it and never got the groups I achieved using BP without reducing the load significantly lower then suggested . Which in turn reduced my FPS and thus effected the down range energy .
The reason for this I believe is the pressure and its pressure curve within the barrel .
So my suggestion would be ‘ IF you have changed powders “ . through out the numbers and work up a load for the AP . Once you have that accuracy your looking for then go back and look at the velocity and down range energy and see if its producing what you feel you need .
Sometimes what looks the same , isn’t really the same .
Do what the other fellas have said here . Check your sights and if they are solid, ask yourself if you honestly think if maybe the problem simply is the case that you have not gotten used to them yet .
If neither is the case then I would look at your powder and if you changed it . If you haven’t , then it has to be the sights . If you have ? Well then your going to have to work up a load for that powder and find a load that your rifle likes when using that powder .
