I have observed through the years that if I switch from one powder to another during the same range time in a specific rifle the true accuracy will not be reflective until a few shots have been fired with the new powder. So I have tried to stick with one powder, or clean and shoot a couple fouling shots prior to shooting my test group. When I tell people this they look at me a funny and say it should not affect the accuracy going from one powder to another without cleaning. So I thought I would get some input from other pros out there!! Your thoughts folks!!!

I have also observed this "effect" and beleive that it has to do with the chemical specific fouling that an individual powder will produce. Different friction and different barrel time/vibrations all add up. Who knows????

quote:

Originally posted by Mohunt:
I have observed through the years that if I switch from one powder to another during the same range time in a specific rifle the true accuracy will not be reflective until a few shots have been fired with the new powder. So I have tried to stick with one powder, or clean and shoot a couple fouling shots prior to shooting my test group. When I tell people this they look at me a funny and say it should not affect the accuracy going from one powder to another without cleaning. So I thought I would get some input from other pros out there!! Your thoughts folks!!!

I have never observed this effect, but have not been looking for it either. There is no reason why it could not happen just as you say.

You might observe correctly but assess the incorrect cause.

I find that after adjusting my scope it takes a few shots and then the shots settle in to good looking groups.

This, I assume, is because of the horribly cheap but very useful scopes I use.

Is it possible that after changing powders you then also adjust the scope for center of bullseye?

Here's what's happening.

No matter how clean burning a powder is there will always been some partially-burned and some unburned kernels of powder in the barel so when you change powders without cleaning the barrel these partially-burned and unburned kernels can burn thus adding to the volumn of gas for the shot. After a few shots the original powder residue (partial and unburned) have been replaced with partial and/or unburned kernels of the new powder being tried.....also the main reason for 1st shot flyers after you clean a barrel and why they tell you to never take a "clean" gun hunting.

Sounds crazy but going from IMR-4064 to IMR-4895 caused me to have to adjust the scope down abit. Back to IMR-4064 and then adjust it down abit!

I have used some powders in my 22-250
that at the same approx velocity would shoot as low as a couple of inches at 100 yards.
H-870 powder has thrown me for a few loops
regarding this also (not in the 22-250 though)

I meant to say tha tI had to adjust down with IMR 4895 and then back up when I changed back to IMR 4064

we knew what ya meant